Have you been meaning to learn more about spotted lanternfly? Here’s your chance!

This isn’t biocontrol, but it’s very important! Have you heard about the invasive spotted lanternfly? Do you want to learn where we are in our efforts to keep it out of New York, and to manage it if (and when) it does show up?

New York State Integrated Pest Management is hosting a meeting in Binghamton, NY on Thursday August 15 where you can get answers to these questions.

This conference has been approved for 7.5 Certified Nursery Landscape Professional credits, and 6 NYS Pesticide Recertification credits in the categories of 1a, 2, 3a, 6a, 9, 10, 22 and 25.

Details:
August 15, 2019
8:30 am – 4:30 pm
Broome County Regional Farmers Market
840 Upper Front St., Binghamton NY

Register online.

Get more information here about speakers and registration costs.

5th Annual New York State Integrated Pest Management Conference Spotted Lanternfly: At our doorstep or already in our fields? It's not if but when and where this invasive pest will show up in NYS. Be on the front line of stopping the invasion! Learn where to look and how to correctly identify and report sightings of all spotted lanternfly life stages. Spotted lanternfly is a concern to: growers; foresters; nursery, greenhouse, and Christmas tree operations, landscapers, Master Gardeners and all NYS residents. In fact, anyone whose business or travel takes them through quarantine zones should understand New York State's regulations. Experts from across PA and NY will provide updates on what is b doen to prevent SLF's establishment in New York and tools available to combat this threat to our fields, forests and homes.

Cereal Leaf Beetle Biocontrol Project Underway

This month’s post is about a project being led by Jaime Cummings, the Field Crops and Livestock IPM Coordinator at NYS IPM. The goal is to improve biological control of the cereal leaf beetle, a pest of small grains. Before we tell you about the biocontrol project, you’ll need some background information on this pest and the other management options available. You can use the following links to navigate to each section of this post:

Cereal leaf beetles and damage they cause

Scouting for cereal leaf beetle and deciding when to spray

Biocontrol of cereal leaf beetle

Our project: Improving biocontrol of cereal leaf beetle

Cereal leaf beetle damage on the flag leaf of a winter wheat plant. (Photo by J. Cummings, NYS IPM)

Cereal leaf beetles and the damage they cause

The cereal leaf beetle (CLB), Oulema melanopus, can be a significant pest of winter and spring small grains production in NY, especially in parts of western NY.  This invasive species was first detected in Michigan in 1962, and has since become established in many grain producing states in the US, despite quarantine and pesticide eradication efforts in the 1960’s and 1970’s.

Left: a black beetle with a red middle (thorax), sitting on the leaf of a small grain crop; Right: a yellowish larva sitting on the leaf of a small grains crop
Figure 1. Cereal leaf beetle adult (A) and larval (B) stages. (Photos by J. Cummings, NYS IPM)

You may be familiar with this pest either in the larval or beetle stage (Fig. 1).  CLB has one or two generations per growing season, and the adults overwinter in hedgerows, woods or field margins.  We usually start seeing the adults move into small grains fields in April or May to lay eggs which develop into the damaging larvae.  The larger the larvae get, the more damage they inflict on the crop.  After about two weeks of feeding, the larvae drop to the ground and pupate for about two weeks before the adults emerge again.

When looking for these pests, keep an eye out for the typical larval feeding damage that looks like strips of green tissue missing between leaf veins.  Severely damaged leaves may appear skeletonized, and intense feeding pressure in a field may result in a ‘frosted’ appearance of flag leaves (Fig. 2).

green heads of winter wheat surrounded by leaves that have tan stripes on them
Figure 2. Severe cereal leaf beetle larval feeding on winter wheat. (Photo by J. Cummings, NYS IPM)

Considering that the top two leaves of the wheat/barley/oat crop are what contributes most to grain yield, severe infestations of CLB can significantly impact yield and grain quality.  Even in small grain or mixed stand forage crops, this pest can have negative effects on the yield and quality of the forage because they can significantly reduce leaf area and photosynthetic capability of the crop.

Scouting for cereal leaf beetle and deciding when to spray

It’s important to scout for this pest, usually starting in early to mid-June when larvae are first appearing.  The economic threshold for insecticide application for CLB is when you count an average of three or more larvae per plant before the boot stage or one or more larvae per flag leaf after the boot stage.  Occurrence of this pest can be inconsistent within a field, therefore plan to scout weekly and walk a random pattern throughout each field stopping at 10 random locations to count larvae on 10 plants at each location.  Because insecticides labeled for CLB target the larval stages, in order for your pesticide applications to be most effective, make sure that at least 25% of CLB eggs have hatched and that larvae are present and actively feeding when you decided to spray.  And, if you’re seeing adults in late June or beyond, it’s probably too late to spray for the larvae.  (Always follow label recommendations and restrictions when applying pesticides)

Paying attention to CLB populations in your fields via scouting is an important part of an integrated management approach for minimizing losses to this pest.  A growing degree day (GDD) model for CLB developed in Michigan determined that adult CLB begin to emerge around 350-400 GDD (base 48) to begin egg laying.

Biocontrol of cereal leaf beetle

Unfortunately, there is no specific host plant resistance available for CLB, but there are natural predators of the larvae and eggs which can help to keep the pest population in check, and possibly below the economic threshold when well-established in an area.  Lady beetles are known to prey on CLB larvae and eggs, and there is at least one egg parasite though it is not widely distributed.

There is also a CLB larval parasitoid wasp, Tetrastichus julis, which was originally introduced from Europe as a biological control agent in Michigan in 1967 (Fig. 3).  Subsequent releases into other states, including NY in 1973, have led to a sporadic establishment of this biological control parasitoid throughout small grain production areas of the US.

Tiny black wasp perched on dark brown larva clinging to a leaf
Figure 3. Tetrastichus julis, a parasitic wasp on a cereal leaf beetle larva. (Photo courtesy of Washington State Department of Agriculture)

Our project: Improving biocontrol of cereal leaf beetle

Given that CLB damage can be widespread and undermanaged in many small grains fields in NYS, and under the advice of Dr. Elson Shields (Cornell University Field Crops Entomologist), the NYS IPM program decided to try to determine the parasitism levels of CLB larvae in various locations around the state and to try to increase populations of the parasitoid in the Aurora area of Cayuga County, where the CLB tends to be a perennial pest.  The multiyear project was initiated this year, with CLB larval collections from locations in six counties.  However, there were no CLB present to collect at two of the locations, so the data collected in 2019 includes only four locations (Table 1).

Table 1.  Cereal leaf beetle collection efforts for determining parasitism levels in 2019.

Location County Collection date Crop # CLB larvae collected
Seneca Falls Seneca 6-Jun winter wheat, rye, barley 96
Aurora/Musgrave Cayuga 12-Jun spring barley 92
Ithaca Tompkins 12-Jun winter wheat, rye, barley 45
Penn Yan Yates 13-Jun spring oats and peas 110
Oriskany Oneida 11-Jun winter wheat 0
Homer Cortland 10-Jun winter wheat 0

 

At each location, a target of approximately 100 CLB larvae of all different sizes/growth stages were collected by hand from wheat, barley or oat fields.  The larvae were temporarily reared in incubation chambers on host plant leaves until approximately half of the larvae were dissected to determine baseline parasitism levels for each location (Fig. 4).

Left: Petri dishes with white filter paper and torn up leaves of oats; Right: Brown and yellow larvae of the cereal leaf beetle (some are squished) on a moist white filter paper in a petri dish
Figure 4. Cereal leaf beetle rearing chambers (A) and dissection process (B). (Photo by J. Cummings, NYS IPM)

The eggs of the parasitoid are visible when the CLB larvae are cut open under a microscope (Fig. 5).

close-up image of squashed yellow larvae. Dark head capsules are still visible, and small oblong eggs of the parasitoid can be seen next to one squished larva. The picture has the following labels: Dissected CLB larvae, and T. julis parasitoid wasp eggs from inside CLB larva
Figure 5. Dissected CLB larvae, and one with T. julis parasitoid eggs. (Photo by J. Cummings, NYS IPM)

After baseline parasitism levels were determined for each collection location, the other half of the CLB larvae were then released at the Cornell Musgrave research farm near Aurora, NY (Fig. 6).  This process will be repeated over the next few years.

Left: Hand hold an open petri dish filled with oat leaves, cereal leaf beetle larvae, and white filter paper; Right: Small dark larvae on an oat leaf with feeding damage
Figure 6. Cereal leaf beetle larvae with known level of parasitism being released in Cayuga County (Photos by J. Thomas-Murphy, Cornell University)

The goals of this project are to determine the established levels of the T. julis parasitoid around the state since the initial release in 1973, and to try to determine if we can increase its population at the research farm through consecutive releases.  From this first year of data collection, we know that the parasitoid population is low at the research farm in Cayuga County (6%) and at two of the collection sites (7% and 10%, in Seneca and Yates Counties, respectively), but was at approximately 30% at the Ithaca (Tompkins County) collection site (Fig. 7).

Graph shows that in Seneca County and Cayuga County only 7% and 6% (respectively) of cereal leaf beetle larvae were parasitized, while in Tompkins County the parasitism rate was 30%, and in Yates County the parasitism rate was 10%
Figure 7. Percent T. julis parasitized cereal leaf beetle larvae collected from various locations.

We also know that although there has been a need to spray insecticides to manage CLB at the research farm in Cayuga County and near the other collection sites, there has been no need to spray for CLB at the Ithaca (Tompkins County) collection sites.  It’s likely that the T. julis parasitoid population at the Ithaca site keeps the CLB population below economic threshold levels.  We hope that by intentionally distributing this parasitoid into an area with known CLB problems, we can establish a robust parasitoid population that may result in a reduction of necessary insecticide sprays for this pest.

This post was written by Jaime Cummings, Ken Wise, and Amara Dunn, all of the New York State Integrated Pest Management Program.

You too can ID aphids…and manage them with biocontrol

Lady beetle on a squash leaf, with a small cluster of pale green aphids nearby.
Caption: Lady beetles will eat any aphid species, but other aphid natural enemies are much more selective. (Photo credit: Amara Dunn)

Practicing good integrated pest management in the greenhouse requires correct identification of the pest. Accurate pest ID is also critical to successful use of biocontrol. Aphids are a good example. Biocontrol of aphids works best when you match the biocontrol agent to the aphid species you have. When I first learned this, I was a bit intimidated, because aphids are pretty small, and I’m not an entomologist. But the four aphid species you are most likely to encounter in your greenhouse are actually pretty easy to differentiate.

Anatomy of an aphid

In order to successfully ID aphids, you need to know (just a little) about aphid anatomy. All aphids are pretty small (between approximately 1/16 and 1/8 inches long). In addition to six legs and a body, aphids have antennae. Antennae attach near their eyes and are angled back over their bodies. They also have two little “spikes” that protrude from their rear end. These are called cornicles. Not so bad, right?

Diagram identifying the antennae on the aphid’s head and the cornicles attached at the rear of the abdomen.
Two features that will help you identify an aphid are the antennae attached to their head, and the two short cornicles attached to the rear end of their abdomen. (Diagram credit: Amara Dunn)

Green peach aphid

Enlarged photo of a light green, green peach aphid with identifying characteristics (indentation between antennae and cornicles that match the color of the body but with dark tips) labeled.
Green peach aphids vary in color from green to pink. Between their antennae you’ll see an indentation, and their cornicles are the same color as their body, with dark tips. (Photo credit: John Sanderson)

Green peach aphids come in different colors (from green to, well, peachy pink) and they are one of the smaller species. Their cornicles are the same color as their body (whatever that color is), and have dark tips on the ends. Green peach aphids also have an indentation in their head between the bases of their antennae.

Melon (or cotton) aphid

Enlarged photo of a dark green melon aphid with the distinguishing dark cornicles labeled.
Melon (also called cotton) aphids can be distinguished from green peach aphids by their dark cornicles. They also lack an indentation between their antennae. (Photo credit: John Sanderson)

Melon aphids (also called cotton aphids) also come in a range of colors that include light yellow, green, dark green, or almost black. Regardless of the body color, the cornicles will always be dark. Also, there’s no indentation in their head between the bases of the antennae. This is another small aphid species.

Foxglove aphid

Enlarged photo of a shiny green foxglove aphid with the distinguishing dark-spotted long antennae, dark leg joints, and darker green spots at the base of the cornicles labeled.
Foxglove aphids are shiny green with long antennae that look like they have dark spots on them. You’ll also see darker green spots at the base of each cornicle and dark leg joints. (Photo credit: Dan Gilrein)

Foxglove aphids are large (for an aphid). Their bodies are light green, but often shiny. There is an indentation in their head between their antennae. Their antennae are extra-long, extending well beyond the end of their body, and appear to have dark spots on them because the joints of the antennae are dark. The joints of their legs are also dark. Check where the cornicles attach to the body of the aphid. Foxglove aphids have darker green spots on their bodies at the base of the cornicles. These aphids usually like to hang out on the lower leaves of a plant, though they will infest flower petals sometimes.

Potato aphid

Enlarged photo of a potato aphid showing the segmented appearance and dark stripe running the length of the body.
Potato aphids have a dark stripe running down the length of their body, and they look faintly segmented. (Photo credit: John Sanderson)

Another large aphid, potato aphids come in pink and green. They look like they have a dark stripe running down the middle of their backs, and their body appears faintly segmented. They also have an indentation in their head between the antennae. Of the four species we’re discussing here, only the melon aphids lack this indentation.

To see these features, you will need a little magnification, but you don’t need a fancy microscope. Find a hand lens or a magnifier with 10X magnification. I like to keep one in my backpack so I’m always prepared.

Picture of a 10X hand lens. The lens folds out from a protective metal cover.
A 10X hand lens will enable you to magnify the features of an aphid that are important for identification.

There are even some relatively inexpensive 10X lenses you can snap on to your smartphone or tablet. Not only does this turn your device into a little microscope, but you can take a picture to document what you see (and show to an expert, later).

Picture of a macro lens that clips on to a smart phone or tablet.
Magnifying macro lenses can be clipped onto your smart phone or tablet, helping you both magnify and document the aphids you find.

You can also find (at least some of) these four aphid species outside. Last summer I spotted the aphid below on an acorn squash plant in August. Now that you know what to look for, what species do you think it might be?

Enlarged photo of a light green aphid with black cornicles. Do you know what species it is?
Use what you’ve learned to identify this aphid! (Photo credit: Amara Dunn)

One minor complication: Each of these four aphid species can either have wings, or be without wings. Usually aphids you find in a greenhouse have no wings, so you can stick with the above descriptions. But winged aphids can appear in the greenhouse, particularly when populations get very high. If you find aphids with wings in your greenhouse, the above descriptions won’t apply; ask for some help from your local extension office.

Enlarged photo of a winged (right) and non-winged (left) green peach aphid. The winged aphid is mostly black and looks very different from the pale green aphid without wings.
Both of the aphids in this picture are green peach aphids, but the one on the right has wings, and would be tricky to identify using the criteria described in this post. Get some help from an expert. (Photo credit: Whitney Cranshaw, Colorado State University, Bugwood.org)

Choosing the right natural enemy

Enlarged photo of a tiny parasitoid wasp surrounded by green aphids that appear to be covered in white wax. The wasp is inserting an egg into one of the aphids.
An Aphidius parasitoid wasp lays an egg inside its aphid prey. The developing wasp will kill the aphid. These happen to be cabbage aphids. (Photo credit: David Cappaert, Bugwood.org)

A good biocontrol option for aphids is a parasitoid wasp from the genus Aphidius. These tiny wasps are called parasitoids because they lay their eggs inside of aphids. As the young wasp grows, it kills the aphid and turns it into a mummy.

Enlarged photo of the tan shell of an aphid (mummy) with a hole in it, still sitting on a leaf
Aphids that are eaten from the inside out turn into dry, brown “mummies”. On this aphid mummy you can see the hole from which the adult wasp emerged. (Photo credit: Ken Wise, NYS IPM)

 

But if you want to purchase Aphidius wasps to release in your greenhouse (or the banker plants and prey that support them; read more here), you’ll need to know which Aphidius species to use. Aphidius colemani works well against green peach and melon aphids, while Aphidius ervi works well against foxglove and potato aphids. Another natural enemy you can use is Aphidoletes aphidimyza. This is a tiny fly whose larvae are voracious aphid predators. Although it seems to be less effective against foxglove aphid, it may work well in combination with another natural enemy.

An enlarged picture of what looks like a segmented worm (the larva of Aphidoletes aphidomyza), surrounded by pale green aphids
The larvae of the tiny fly Aphidoletes aphidomyza crawls around on leaves searching for aphids to eat. (Photo credit: Sarah Jandricic)

Like all biocontrols, Aphidius wasps and Aphidoletes larvae need to be released while your aphid population is very small, before it gets out of hand. Aphid infestations can explode very quickly! Scout your crop regularly, and keep records so you know which aphid species you are likely to have. (Consider the Pocket IPM Greenhouse Scout app to help you with your scouting and pest management.) Then plan your biocontrol releases accordingly. Parasitoids and predators for aphids should be released preventatively on crops that are prone to aphids.

If you’ve inspected your aphids at 10X magnification, and still aren’t sure which species you have, contact your local extension office for help with ID. If you are planning to send a picture, make sure that it is clear and shows the features of the aphid that you now know are important (antennae, body, cornicles).

You can learn more about aphid biocontrol in this factsheet from John Sanderson (Department of Entomology, Cornell University) on managing aphids in a greenhouse. Identification of these four common aphid species and which biocontrols you can use against them are also summarized here. The natural enemies listed in the chart are meant to be a starting place. Maximizing the efficacy of your aphid biocontrol program takes some trial and error and willingness to fine-tune your program to the crop and environmental conditions you’re dealing with. Suppliers of aphid natural enemies also have great information about how to use these biocontrol agents most effectively.

Happy aphid hunting!

This post was written by Amara Dunn and Betsy Lamb (NYS IPM) and John Sanderson (Entomology, Cornell University).

Creating habitat for beneficial insects: Starting Year 2

A close-up picture of a lady beetle on a plant
Lady beetle from our beneficial insect habitat plots

Last year I introduced you to the research field at Cornell AgriTech in Geneva, NY where Dr. Betsy Lamb, Brian Eshenaur and I are studying and demonstrating Christmas tree IPM. One part of this project is using perennial wildflowers to attract natural enemies of pests as part of an IPM strategy. The wildflowers (and some perennial grass) species were chosen because of the food and shelter they provide to pollinators. These same resources should make them useful to natural enemies of pests, too.

A plot containing wildflowers (some yellow and purple ones in bloom), with woodchip mulch visible between plants.
Mulching transplants planted in Spring 2018 was the most expensive establishment method, but these plots were looking pretty good a year later, even before we weeded.

By the end of our first field season, we had started using six different methods to establish wildflowers as habitat for beneficial insects (plus a weedy mowed control treatment). We also collected data on how much time and money we spent on establishment and how successful our weed management was. You can read about results from Year 1 in my post from last November.

But beneficial insect habitat establishment is not a one-year project. The establishment methods we started to implement in 2018 are ongoing, including periodic mowing of direct seeded plots, and hand-weeding of transplanted plots. We’ll keep track of how much time and money we invest in these plots in 2019, too.

The same plot is shown in two pictures. The picture on the left has some bare ground visible and many patches of grass and broadleaf weeds. The picture on the right shows the plot after it was mowed.
Plots that were direct seeded in 2018 will be mowed this year to favor the perennial beneficial insect habitat plants over annual weeds. This plot was treated with alternating herbicide and tillage during Summer 2018, and wildflower seed was planted in Fall 2018; (A, left) plot before mowing, (B, right) same plot after mowing.
Two pictures of the same plot before (left) and after (right) weeding. The un-weeded plot has lots of dandelion seed heads and no bare ground is visible. After weeding, you can see some bare ground and it’s easier to see the wildflower plants.
Plots that were transplanted in 2018 will be hand weeded this year to help the perennial wildflowers and grasses out-compete weeds. This plot was transplanted in Spring 2018 into bare (not tilled) ground and no mulch was used; (A, left) plot before weeding, (B, right) same plot after weeding.

And we want to know whether these plots are actually attracting beneficial or pest insects. So, in 2019 we are starting “Phase II” of our beneficial insect habitat work. We want to know which and how many insects (and other arthropods, like spiders) are being attracted to each type of plot. We will also count insects in no habitat plots (weedy, mowed occasionally) and mowed grass plots in the middle of the Christmas tree field for comparison.

Insect collection began in early May, and we are using four different techniques:

  • Sweep net – This is what it sounds like. We “sweep” a net through the air above the ground to capture mostly flying insects, or those who may be resting on the plants.
  • Butterfly and moth count – We walk through the field, counting how many of each butterfly or moth species we see in each plot.
  • Pan traps – These are bright yellow and blue bowls filled with soapy water. One bowl of each color is placed in each plot for 2 days, then we collect the insects that have been attracted to the colorful bowls and were trapped in the soapy water. This method will help us count flying insects, especially bees and wasps.

    A bright blue plastic bowl and a bright yellow plastic bowl are filled with soapy water and small rocks. Both are set on bare ground with some plants growing nearby.
    Bright blue and yellow bowls filled with soapy water and weighed down with rocks will attract certain flying insects. By counting insects collected in these pan traps, we can learn which insects are spending time in each plot.
  • Pitfall traps – These are clear plastic 16-oz deli cups (like you might use for take-out food) that are sunk into the ground in each plot. Insects that crawl along the ground fall in. We will use this method to count mostly ground-dwelling insects.

    A 16-ounce plastic deli cup sunk in bare soil of a plot so that the rim is level with the ground. The cup is half-full of liquid and also has caught a few green beetles. The trap is covered by a clear plastic dinner plate held about 6 inches above the ground by wire legs.
    A pitfall trap collects ground-dwelling insects. This one is protected by a rain cover. We didn’t want all the rain we’ve been getting this spring to overflow the traps and wash away the insects we caught!

I will write another blog post or two about this project during or at the end of this season. If you want to see more frequent updates, follow me on Twitter (@AmaraDunn). I’ll post weekly pictures of this project, including which beneficial insect habitat plants are blooming each week. You can also see lots of pictures from this project on Instagram (biocontrol.nysipm).

Battling Fire Blight with Biologicals

This post was written by Anna Wallis, Kerik Cox, and Mei-Wah Choi (all from Cornell’s School of Integrative Plant Science, section of Plant Pathology and Plant-Microbe Biology). Thanks for sharing your research with us!

Since this is a slightly longer post, here’s a little table of contents:

Biological Modes of Action

What products are currently available and where do they fit in?

Results from the Cox lab

The verdict on biologicals for fire blight management

Streptomycin is a clear asset in the fire blight arsenal—it is inexpensive, effective, and reliable. However, antibiotics may not always be a viable option. More and more, biological materials are holding their own in the fight, with an increasing number of products on the market claiming protection for both blossom and shoot blight. Biological materials are still relatively new to the apple scene, an industry with a long track record of effective disease management. So why change to biologicals, and how do they work?

There are a multitude of reasons driving the growth of antibiotic alternatives. Organic production eliminated antibiotic use in 2014 in the United States. In European markets, they are prohibited or severely limited. Pressure from regulatory organizations and markets to use more sustainable management techniques will not be slowing any time soon. The prevailing evidence supports that responsible streptomycin applications do not seem to select for resistance in the pathogen. Yet, resistance continues to appear in commercial settings.

So, what are these biological materials and how do they work? In the ‘What is Biocontrol?’ tab above, Amara provides an excellent overview of biocontrol, as defined by the EPA and industry. Here I’ll review the biological modes of action and specific materials available in the context of fire blight management. I’ll also provide a snapshot of how biological programs have performed in our research orchards. There is no intention to endorse any specific trade products, rather this is an attempt to provide a neutral perspective and overview of the current market.

Biological Modes of Action

Biological materials available for fire blight management are typically biopesticides falling into the biochemical or microbial category. This means they are derived from natural sources (i.e. plant extracts or minerals) or they are composed of microcorganisms and/or their products.

To understand how biologicals can be used in fire blight management, it’s first important to review the important features of the disease. A thorough description of the disease cycle, symptoms, and causal organism can be found on this Cornell Fact Sheet. Fire blight is caused by Erwinia amylovora, a bacterial pathogen which preferentially colonizes the floral surface, specifically the stigma or the sticky part of the tip of the female organ. First, enough heat must be accumulated for colonization to occur, which can be predicted by disease forecasting models such as MaryBlyt (if you’re familiar with the disease and pest prediction tool NEWA, this is the model used in the fire blight prediction model there). Then there must be a wetting event to wash the bacteria into the natural openings in the flower, the nectary at the base of the floral cup. Unlike fungi, bacteria cannot penetrate plant cells directly, so they rely on natural openings and tissue damage to invade their host.

Pictures (counterclockwise, from top left) of a yellow glob of bacteria oozing out of a dark, necrotic canker on an apple stem; a dead cluster of apple blossoms; a dead apple shoot curved like a shepherd’s crook; the base of an apple tree trunk with a dark canker.
Figure 1. Simplified disease cycle for Erwinia amylovora, causal agent of fire blight. Clockwise from top left: primary inoculum is produced in the spring as bacterial ooze from old cankers; inoculum is transferred to open flowers and causes blossom blight; blighted blossoms provide additional inoculum which is transferred to young leaf tissue damaged by wind or hail causing shoot blight; bacteria may also travel systemically via the vascular system of the plant leading to canker blight; cankers produced from blossom, shoot, or canker blight provide an overwintering site for bacteria to colonize the tree in the following season.

Biologicals can disrupt these events by:

  1. Outcompeting the bacteria during colonization of the plant
  2. Producing antibiotic metabolites, killing the pathogen prior to infection, or
  3. Priming natural host defenses, making the plant more resistant to the bacteria. This is called ‘Induced Resistance’

A simplified view of these events is depicted in Figure 2.

Two identical pictures of a cluster of open apple blossoms. Left photo with a red circle around the yellow floral parts (stigmas) and a blue curved arrow from this circle to the base of the flower (nectary), representing the colonization of the stigma by E. amylovora and a wetting event washing the bacteria into the plant. Right photo with the red circle and blue arrow, plus a yellow ‘X’ over the red circle, indicating protectant activity at the stigmatic surface, and a brown ‘T’ with the top facing the stigma, indicating the induction of plant defenses.
Figure 2. Depiction of fire blight blossom infection and how biological materials interfere. (A) In order for a blossom infection to occur, flowers must be open and receptive, heat accumulation must be sufficient for E. amylovora to colonize the stigma (red circle), and there must be a wetting event (blue arrow) to wash the bacteria into the floral nectary. (B) Biological materials protect against infections by outcompeting the pathogen or producing antibiotic metabolites (yellow ‘x’) or priming host defenses (red letter “T”).

Like any product, these materials require precise applications, to ensure they are in the right place at the right time to provide effective control (Figure 3). Materials with competitive action or antimicrobial metabolites that ‘protect’ the flower (protectants) must be applied when the bacteria is present or just before. This enables sufficient, timely colonization or interaction with the pathogen. Induced resistance materials (defense inducers), also called Systemic Acquired Resistance or Induced Systemic Resistance materials (SARs or ISRs), must be applied prior to infection events, with enough time to activate the host response. (Click the image below to enlarge it.)

Seven pictures of apple buds in a row, depicting growth stages in chronological order: 1. dormant (closed, brown buds), 2. green tip (green leaves just starting to emerge), 3. half inch green (about ½” of green showing), 4. tight cluster (cluster of green floral buds in center of emerged leaves), 5. pink (floral buds showing pink color), 6. bloom (open blossoms), and 7. petal fall (cluster of very small fruitlets). At several stages, words are printed above indicating actions to be taken for fire blight management. At dormant “Prune out cankers”, at green tip “Copper”, at pink “Pre-bloom defense inducers”, at bloom “Protectants”, at petal fall “Post-bloom defense inducers.”
Figure 3. Approximate timing of biological materials corresponding to phenological stages of apple for blossom and shoot blight protection. In any fire blight management program, it is essential to remove inoculum (old cankers) during the dormant period and apply a general antimicrobial at green tip to reduce inoculum. Blossom blight control is provided by defense inducers applied prior to bloom and protectants applied at bloom. Additional applications of defense inducers post-bloom provide shoot blight control; some of the earlier applications targeting blossom blight seem to also have some carry-over effect for shoot blight.

What products are currently available and where do they fit in?


Blossom protectant type products include both bacteria and fungi. The most well-known examples include: Pantoea agglomerans, a bacterium closely related to the fire blight bacterium and an excellent colonizer of apple flowers, marketed as Bloomtime Biological (Northwest Agricultural Products), and the yeast Aureobasidium pullulans, a fungus, marketed as Blossom Protect (Westbridge Agricultural Products). Another bacterium, Pseudomonas fluorescens, is also an effective competitor and is marketed as BlightBan (NuFarm).

Materials with antimicrobial activity are most often Bacillus species, most commonly strains of B. amyloliquefaciens and B. subtillus. Currently on the market are Serenade Optimum (Bayer), Double Nickel (Certis), and Serifel (BASF).

Products that stimulate Induced Resistance response in the host plant work by stimulating two possible pathways the ISR and SAR, as mentioned earlier. These pathways are related and overlapping in the plant, and scientists are still detangling the complex molecular mechanisms involved in plant protection. Example products include Regalia, an extract of the plant Reynoutria sachaliensis or giant knotweed (Marrone Bio Innovations) and a Bacillus mycoides strain marketed as LifeGard (Certis). Another common product used in induced defense is acibenzolar-S-methyl. This is not a biological, but a synthetically derived product marketed as Actigard (Syngenta).

Many of these products have been recommended as part of an integrative management strategy outlined in an extensive report from The Organic Center, based on results from both research trials and anecdotal experience (Ostenson and Granatstein 2013). Always follow the label on any pesticide (including biopesticides) you use.

Table 1. Biological products for Fire Blight

Product Active Ingredient Mode of Action
Firewall Streptomycin antibiotic – kills pathogen
Blossom Protect Aureobasidium pullulans strains DSM14940 & 14941 competitive with pathogen
Bloomtime Biological Pantoea agglomerans strain E325 competitive with pathogen
BlightBan Pseudomonas fluorescens strain A506 competitive with pathogen
Serenade Optimum Bacillus amyloliquefaciens strain QST713 antibiotic metabolites
Double Nickel Bacillus amyloliquefaciens strain D747 antibiotic metabolites
Serifel Bacillus amyloliquefaciens strain MBI600 antibiotic metabolites
Regalia extract of Reynoutria (giant knotweed) resistance inducer
LifeGard Bacillus mycoides isolate J resistance inducer

Results from the Cox lab


Our lab conducts extensive trials evaluating efficacy and sustainability of disease management programs in our research orchards at Cornell AgriTech in Geneva. More recently testing has included various biological materials. In these trials, management programs are tested in two orchard blocks: a Gala block and an Ida Red block, established in 2002 and 2004 respectively, both on B.9 rootstock. The trees in these blocks are spaced considerably farther apart than commercial orchards in order to prevent drift between treatments.

Programs targeted either blossom or shoot blight. To provide sufficient disease pressure, trees are inoculated with a high concentration of E. amylovora at bloom. In blossom blight programs, resistance inducers are applied at pink, and protectants are applied at bloom. For shoot blight programs, resistance inducers are applied at petal fall.

Disease pressure varied from season to season, as indicated by the untreated control trees, ranging from 60 to 99 % disease incidence. Across all trials, antibiotics provided the most consistent and reliable control of both blossom and shoot blight, with less than 15% blossom and 5% shoot blight. The biological materials, both protectants applied at bloom and defense inducers applied pre-infection, also provided good disease protection with typically less than 30% incidence depending on the season conditions and the product. Compared to antibiotic programs, these materials showed greater variation both within and between seasons (i.e. greater standard deviation within a treatment and different top performers in different seasons). In seasons with lower disease pressure, biological programs tended to perform as well as antibiotics. Some of the specific results from 2015-17 are shown in Figure 4 (click the image to enlarge the graphs).

Disease was most severe in the untreated control, ranging from 60% to more than 90% of blossoms blighted and 30% to more than 50% of shoots blighted. Pressure was high in 2015 and 2017, lower in 2016. The antibiotic streptomycin always had <20% and often 0% incidence. Defense inducers outperformed protectants in 2015. In 2016 and 2017 defense inducers and protectants performed similarly, and overall disease incidence was lower.
Figure 4. Average disease incidence of four replicate trees treated with fire blight management programs in 2015 (A & D), 2016 (B & E), and 2017 (C & F). Programs included untreated control (grey bar; highest disease pressure), antibiotics (maroon), resistance inducers (blue), and blossom protectants (yellow).

The verdict on biologicals for fire blight management


Do we recommend biological materials for fire blight management? Overall, the answer is generally yes. There are several important considerations to consider. In our research orchards, the system is challenged with a very high level of inoculum to examine fine differences in product performance. These inoculum levels are much higher than would be present in most commercial orchards. Hence, we expect all programs would perform even better in a commercial setting. In addition, combinations of products seem to be the best: for example, pairing a defense inducer applied at bloom with a protectant material at bloom to control blossom blight, with follow up defense inducer applications for shoot blight. We also expect efficacy of biological materials to improve in the future. Changes in formulations improving activity (note the old and new Regalia formulations in Figure 3), as well as shelf life, tank mixing, and storage happen fairly regularly and will make products more accessible and affordable for growers.

Biologicals are still relatively new materials. As with any product, there is still much to learn about how products work in the field, the most effective management programs, and translating best practices from research to commercial settings. We believe they are a valuable part of an integrated fire blight management approach, including good cultural and mechanical practices such as planting resistant cultivars and rootstocks and removing inoculum from the orchard.

 

You can learn more from these sources:

Ostenson, H., and Granatstein, D. Grower Lessons and Emerging Research for Developing an Integrated Non-Antibiotic Fire Blight Control Program in Organic Fruit. The Organic Center. November 2013. Available at: https://www.organic-center.org/wp-content/uploads/2013/07/TOC_Report_Blight_2b.pdf

Pal, K., and Gardener, B. 2011. Biological Control of Plant Pathogens. The Plant Health Instructor, APS. Available at: https://www.apsnet.org/edcenter/advanced/topics/Pages/BiologicalControl.aspx.

Turechek, W. W., and Biggs, A. R. 2015. Maryblyt v. 7.1 for Windows: An Improved Fire Blight Forecasting Program for Apples and Pears. Plant Health Progress. 16:16–22. Available at: https://www.plantmanagementnetwork.org/pub/php/volume16/number1/PHP-RS-14-0046.pdf

And the results are in…from Year 1. What do biofungicides add to vegetable disease management Part 3

Cucurbit powdery mildew on a winter squash leaf.
One of our goals for this project was to understand what biofungicides might add to a cucurbit powdery mildew management program.

Introduction

In 2018 we conducted field trials using biofungicides in cucurbit powdery mildew and snap bean white mold management programs. Hopefully you’ve read part 1 and part 2 of this biofungicide story. If not, now might be a good time.

Part 1 will give you more details about the trial design. We wanted to know whether adding biofungicides would improve disease control, plant health, or yield. For cucurbit powdery mildew, we were adding one of three different biofungicides to a conventional chemical spray program. We also included a treatment that was all OMRI-listed (organic) products. For white mold on snap beans, we were curious about using an in-season biofungicide (Double Nickel, Bacillus amyloliquefaciens strain D747) in combination with a pre-season biofungicide (Contans, Paraconiothyrium minitans strain CON/M/91-08). In 2018, our white mold treatments were just Double Nickel and Cueva (an OMRI-listed copper). In 2019, we’ll add the pre-season Contans treatment.

Part 2 explains more about the modes of action of the five biofungicides we are looking at. The post also includes practical information about how to use these biofungicides to maximize their efficacy – compatibility with other products, best way to store them, when to apply them, etc.

Now it’s time to talk about what we learned from this first year (of a two-year project).

The bottom line

We don’t want to keep you in suspense, so here’s a quick summary of what we learned. Fortunately for the eastern NY grower who graciously allowed us to run the trial on his farm (but unfortunately for us), the snap bean field had very little white mold in 2018. Even the plots that were not sprayed with Double Nickel or Cueva had almost no disease. So we weren’t surprised when there were no differences in disease, plant health, or yield among the white mold treatments. Results from Sarah Pethybridge’s efficacy trials with OMRI-approved products for white mold are available online.

A healthy field of snap bean plants.
Our snap bean trial in eastern NY in 2018 had very little white mold. (Photo credit: Crystal Stewart)

Cucurbit powdery mildew was a bit more severe than white mold (low pressure in eastern NY, moderate pressure in western NY and on Long Island), but we were not able to detect statistically significant benefits from adding biofungicides to a conventional spray program. Disease severity, plant health (as measured by NDVI), yield, and fruit quality (Brix) were the same whether you used a conventional spray program, or a conventional spray program plus a biofungicide. We didn’t measure significant differences in yield among any of the treatments at any of the three sites.

The conventional powdery mildew spray program alone, or when combined with LifeGard, Regalia, or Serifel significantly reduced disease compared to no treatment for cucurbit powdery mildew. Adding any of the biofungicides to the conventional spray program did not improve control compared to using only the conventional sprays. The organic (OMRI-listed products) treatment was not significantly different from either no sprays at all, or the conventional spray program.
Severity of powdery mildew on the upper sides of the leaves in the Western NY trial. Here, disease severity is quantified using the area under the disease progress curve (AUDPC). This number summarizes disease severity from multiple dates, and the larger the number, the worse the disease. If two treatments share the same letter, the average disease in those treatments is not significantly different. The error bars give you an idea of how much variability there was in each treatment.

NDVI results

NDVI (normalized difference vegetation index) values did not detect cucurbit powdery mildew early. (Since there was so little white mold, we couldn’t test NDVI for early detection.) There was some inconsistent correlation between NDVI readings and disease, yield, and Brix in winter squash. In WNY we used both a handheld GreenSeeker and a gator-mounted Crop Circle to measure NDVI. Both devices had similar results. Based on this first year of testing with these two devices, NDVI measurements were not useful as an early indicator of cucurbit powdery mildew.

In addition,  NDVI measurements did not  detect subtle differences in plant health among treatments. At only one of our three sites (Long Island) were there any significant differences in NDVI among treatments. This was only on the last two rating dates in the season, when powdery mildew was visibly more severe in the non-treated control than the conventional fungicide treatments.

On the last two rating dates of the season (August 31 and September 17), NDVI values were significantly higher in the conventional powdery mildew spray program treatment and all three of the conventional + biofungicide treatments, compared to the plots that were not treated for powdery mildew. Adding the biofungicides did not significantly improve NDVI, compared to using only conventional products.
Normalized difference vegetation index (NDVI) measured on winter squash in the Long Island trial on three dates at the end of the season. NDVI values closer to 1 indicate more healthy, green foliage. If two treatments have the same a letter on the same date, the average NDVI readings on that date were not different between the two treatments. Data from August 31 are labeled with uppercase, while data from September 17 are labeled with lowercase letters. There were no differences among any treatments on August 24. The error bars give you an idea of how much variability there was in each treatment. We couldn’t do statistics on the organic treatment because too many plants were killed by Phytophthora blight in the plots that received this treatment.

Some caveats

The non-treated control (received no powdery mildew fungicide) was often not significantly different from the conventional fungicide control (our best management program). We know that controlling powdery mildew on cucurbits is important, so if we don’t detect a significant difference between the non-treated control and the treatment that should have provided the best control, it is then hard to draw further conclusions from the data.

We didn’t measure statistically significant differences in marketable yield among any of the treatments at any of the sites. Data for eastern NY are shown in this graph.
We didn’t detect statistically significant differences in marketable yield among any of the treatments in any of the trials. Here are the data from eastern NY. Notice that all six bars are labeled with the letter “a”. As with previous graphs, the error bars give you an idea of how much variability there was across the different plots in each treatment.

When disease pressure is low (as it was in Eastern NY), we would expect not to see many differences between treatments. Similarly, if the conventional fungicide program provided excellent disease control (as it did on Long Island), it would be hard to detect an improvement in control from adding a biofungicide. Another challenge we dealt with in the Long Island trial was Phytophthora blight. By the end of the season, we had lost two of the four plots receiving the organic treatment to this disease. This limited our ability to statistically analyze the biofungicide data. On Long Island, the organic spray program initially performed well – as seen on August 31  – comparable to the conventional treatments. But by the final assessment on September 17, the organic program was no longer as effective. This was not surprising since it was 10 days after the last application. Suffoil-X was the final organic product applied, and it has little residual activity.

In the Long Island trial, there was very little disease on August 16 or 24. On August 31, disease had increased in the non-treated control, but the organic treatment was still suppressing disease well. Control in the organic treatment had declined by September 17, but this was 10 days after the last spray was applied.
Average severity of powdery mildew on the upper surface of leaves on the last four assessment dates in the 2018 Long Island trial. All of the treatments (except the non-treated control) suppressed powdery mildew well through August 31. Control in the organic treatment had declined by September 17, but this was 10 days after the last spray was applied.

In WNY, we had an epic aphid outbreak. An entomologist colleague identified them as probably melon aphids, and also that 2018 was generally a bad year for aphids. It’s also possible that while trying to control cucumber beetles earlier in the season, we killed some aphid natural enemies, contributing to an aphid outbreak later in the season. I know cucumber beetles are tough, but if you can manage them without decimating your local natural enemies, you’ll be doing yourself a favor!

The underside of a squash leaf covered with aphids; an acorn squash fruit covered with shiny honeydew from aphids; a close-up picture of an adult aphid and some young aphids.
The severe aphid outbreak in the western NY trial may have made it more difficult to detect differences among treatments. In late August, some of the leaves were covered with aphids (A), and many fruit were covered with honeydew (B). Getting a close look at the aphids is essential for correct identification (C).

We deliberately used a very intensive spray program, starting our biofungicide applications early, and continuing to apply them as we added conventional fungicides later in the season. This was an expensive powdery mildew management program. But, in this first year of the project, we didn’t want to be left wondering if a lack of differences was due to underapplication of the biofungicides.

If you want to see more of the data we collected from the cucurbit powdery mildew trial, you can find it in the Proceedings from the 2019 Empire State Producers Expo.

What does this all mean?

First, this is only the first year of our project and one year of data. It’s a start, but we’ll hopefully learn more in a second year. Since we didn’t measure a significant improvement in yield, we didn’t see evidence that adding biofungicides to a full chemical spray program for powdery mildew justified the cost. The relative costs of the treatments we used are listed in the table below, and the approximate per acre costs of each product are in the Proceedings from the 2019 Empire State Producers Expo. Replacing a chemical spray or two with a biofungicide could be a more economical option. That’s something we’re planning to look at in 2019.

Treatment
Date Non-treated Conventional Conventional + LifeGard Conventional + Regalia Conventional + Serifel Organic
7/19/18 LifeGard Regalia Serifel LifeGard
7/27/18 LifeGard Regalia Serifel LifeGard
8/3/18 Vivando LifeGard + Vivando Regalia + Vivando Serifel + Vivando MilStop
8/10/18 Quintec LifeGard + Quintec Regalia + Quintec Serifel + Quintec Serifel
8/17/18 Luna Experience LifeGard + Luna Regalia + Luna Serifel + Luna SuffoilX
8/24/18 Vivando LifeGard + Vivando Regalia + Vivando Serifel + Vivando MilStop
8/31/18 Quintec LifeGard + Quintec Regalia + Quintec Serifel + Quintec Serifel
9/7/18 Luna Experience LifeGard + Luna Regalia + Luna Serifel + Luna SuffoilX
Total cost (per A) $228.28 $343.32 $536.28 $696.28 $257.76
Cost increase vs. conventional (per A) $  – $115.04 $308.00 $468.00 $29.48

Based on results from this year, we can’t yet recommend that you run out and buy a handheld NDVI sensor for early detection of cucurbit powdery mildew. We’ll collect NDVI data again in 2019, and let you know what we learn. Although our results from the field trials were somewhat inconclusive in this first year, we’re hopeful that the information we’ve compiled about how these biofungicides work and how to use them will be useful. If you’re thinking of using Contans, Double Nickel, LifeGard, Regalia, or Serifel in 2019, first take a look at these fact sheets related to our white mold and powdery mildew trials. And if you have used biofungicides, we’d be interested in hearing about it; click here to send an e-mail.

This post was written by Amara Dunn (NYS IPM), Elizabeth Buck (Cornell Vegetable Program), Meg McGrath and Sarah Pethybridge (both Plant Pathology & Plant-Microbe Biology, School of Integrative Plant Science, Cornell University), Crystal Stewart (Eastern NY Commercial Horticulture Program), and Darcy Telenko (Department of Botany & Plant Pathology, Purdue University). Thank you to the New York Farm Viability Institute for funding.

How do they work? Bioinsecticide edition

When an insect is treated with the right bioinsecticide, the insect stops damaging plants, and eventually dies.
Bioinsecticides include microorganisms and other naturally-derived compounds that control insect pests.

My post from last February described modes of action for biopesticides that target plant diseases…as well as the difference between a biopesticide and a biostimulant. January’s post described the modes of action of five biofungicides in an ongoing vegetable trial. But there are plenty of insect and mite pests out there, too. You can attract or release predatory or parasitic insects and mites or beneficial nematodes to deal with these arthropod (insect and mite) pests. But you can also use bioinsecticides that control insects and mites. The active ingredients include microorganisms (bacteria, fungi, viruses), plant extracts, or other naturally-occurring substances. Want to know how they work? Keep reading.

Bioinsecticides can have one (or more) of the following modes of action:

  1. Kill on contact
  2. Kill after ingestion
  3. Repel
  4. Inhibit feeding
  5. Inhibit growth
  6. Inhibit reproduction

The examples included in the following descriptions are reported either on the bioinsecticide labels or in promotional materials produced by the manufacturers. And these are just examples, not meant to be an exhaustive list of bioinsecticides with each mode of action.

Killing on contact

Tiny spores of insect-killing fungi land on the body of an insect, germinate, infect the insect, grow throughout its body, and eventually kill it.
Some bioinsecticides contain living spores of a fungus. These spores need to land on the insect. Then they germinate (like a seed), invade and grow throughout the body of the insect, and eventually kill it. If the humidity is high enough, the fungus may even produce more spores on the body of the dead insect.

Some bioinsecticides need to directly contact the body of the insect or mite in order to kill it. Bioinsecticides that contain living fungi work this way. The tiny fungal spores land on the insect or mite pest, germinate (like a seed), and infect the body of the pest. The fungus grows throughout the pest’s body, eventually killing it. If the relative humidity is high enough, you might even see insects that look like they are covered with powder or fuzz (but this is not necessary for the pest to die). This powdery or fuzzy stuff growing on the pest is the fungus producing more spores. Bioinsecticides that contain the fungal species Beauveria bassiana (e.g., BotaniGard, Mycotrol), Metarhizium anisopliae or brunneum (e.g., Met52), or Isaria fumosorosea (NoFly) are examples of fungal bioinsecticides with contact activity.

An insect covered in the white powdery fungus that has started growing out of its body following infection.
If the relative humidity is high enough, insects infected with a fungus may start growing new fungus on the outside of their bodies, appearing fuzzy or like they are covered in powder. Photo credit: Louis Tedders, USDA ARS, Bugwood.org

Bioinsecticides that contain spinosad (including Entrust, SpinTor, and others) work because the active ingredient affects the nervous and muscular systems of the insect or mite, paralyzing and eventually killing it. It can kill the pest either through contact, or through ingestion (more on that in a moment). The bioinsecticide Venerate contains dead Burkholderia bacteria (strain A396) and compounds produced while growing the bacteria. One mode of action of Venerate is that it contains enzymes that degrade the exoskeleton (outer shell) of insects and mites on contact.

Killing by ingestion

Some bioinsecticides need to be eaten (ingested) in order to kill. Pesticides that contain the bacteria Bacillus thuringiensis (often called Bt for short) as the active ingredient are a good example. Proteins that were made by Bt while the bioinsecticide was being manufactured are eaten by insects and destroy their digestive systems. Several different subspecies of Bt are available as bioinsecticides, and the subspecies determines which insect pest it will be effective against. There are many bioinsecticides registered in NY that contain Bt as an active ingredient. Check NYSPAD for labels, and make sure you choose the right pesticide for the pest and setting where you need control. Bt products do not work on mites, aphids, or whiteflies.

A caterpillar eats a bioinsecticides that kills by ingestion. Later, the caterpillar dies.
Some bioinsecticides (blue diamonds in this diagram) will only kill pests if they are eaten first. Pesticides that contain Bacillus thuringiensis (Bt) bacteria or insect viruses are examples of this mode of action.

Insect viruses are another example of a bioinsecticide active ingredient that kills through ingestion. For example, Gemstar contains parts of a virus that infects corn earworms and tobacco budworms. Once these caterpillars eat the Gemstar, the virus replicates inside the pest, eventually killing it.

Repel

Some bioinsecticides repel insects from the plants you want to protect. However, this mode of action may only work on certain pest species, or certain life stages of the pest. Read and follow the label. Bioinsecticides containing azadirachtin or neem oil, and Grandevo are reported to have repellent activity for some pests. Grandevo contains dead bacteria (Chromobacterium substugae strain PrAA4-1) and compounds produced by the bacteria while they were alive and growing.

One leaf has been treated with a bioinsecticides that repels pests, but one leaf has not. The caterpillars are feeding on the leaf that was not treated.
Some bioinsecticides (blue diamonds and happy microbes in this diagram) protect plants because they repel insect and mite pests. This protects treated plants from pest damage.

Inhibit feeding

If you want insect and mite pests dead as soon as possible, I understand the sentiment. But in many cases stopping the pests from eating your plants would be just as good, right? Some bioinsecticides cause pests to lose their appetite days before they actually die. Like bioinsecticides that kill pests outright, some bioinsecticides that inhibit feeding require ingestion, while others work on contact. And these bioinsecticides may work this way for only certain pest species of certain ages. Read and follow those labels! Bioinsecticides containing Bt require ingestion and some can stop pest feeding before actually killing the pest. The same goes for Gemstar (corn earworm virus). This is another mode of action of azadirachtin products against some pests.

A caterpillar eats or comes in contact with a bioinsecticide that causes the caterpillar to stop feeding.
Some bioinsecticides (blue diamonds and happy microbes in this diagram) cause insect and mite pests to lose their appetites. Depending on the bioinsecticide, it either needs to contact the pest or be eaten by it.

Inhibit growth

Many insects and mites need to molt (shed their skin as they go from one life stage to another). Bioinsecticides that interfere with molting prevent pests from completing their life cycle. Like feeding inhibitors, these bioinsecticides won’t directly kill the pests you have, but they can prevent them from multiplying. This is another mode of action (again, for certain pests at certain stages of development) listed for azadirachtin products and Venerate (Burkholderia spp. strain A396).

Some aphids were treated with a bioinsecticides that inhibits growth. They stay the same size. Another aphid that was not treated grows and molts normally.
Some bioinsecticides (blue diamonds in this diagram) don’t kill insects and mites outright, but they can prevent them from molting and growing into the next life stage. Pests that can’t move on to the next life stage will eventually die without completing their life cycle.

Inhibit reproduction

There are two main types of bioinsecticides that prevent or slow insect reproduction. Pheromones are compounds that confuse insects that are looking for mates. If males and females can’t find each other, there won’t be a next generation of the pest. Pheromones can be especially useful when the adults that are looking for mates don’t feed (e.g., moths). Isomate and Checkmate are two examples of pheromones available for certain fruit pests. Other bioinsecticides actually reduce the number of offspring produced by a pest. This is one of the modes of action of Grandevo (Chromobacterium substugae strain PRAA4-1) against certain pests.

Male and female moths are unable to find each other and mate because of the presence of pheromones nearby.
Pheromones (represented here by blue diamonds) are a type of bioinsecticide that confuses insects looking for a mate. As a result, males and females can’t find each other, don’t mate, and don’t lay eggs.

Why do I care?

Do you mean besides the fact that you are a curious person and you want to know how biopesticides work? Knowing the mode of action for the pesticide you use (among other things) allows you to maximize its efficacy. Does the bioinsecticide need to contact the pest, or be eaten by it? This determines where, when, and how you apply it. Do you want to use a bioinsecticide that inhibits growth of the pest? Make sure you use it when pests are young. (Sidenote: Like all biopesticides, bioinsecticides generally work best on smaller populations of younger pests.) Is the first generation of the pest the one that causes the most damage? Don’t rely on a bioinsecticide that inhibits reproduction. Although if the pest overwinters in your field and doesn’t migrate in, maybe you could reduce the population for the next season.

Now is a great time of year to consider the insect and mite pests you are likely to encounter this season, then learn which bioinsecticides include these pests (and your crop and setting) on the label. Always read and follow the label of any pesticide (bio or not). How do you know whether these bioinsecticides are likely to work in NY on the pests listed on the label? That’s a topic for another post. In the meantime, the Organic Production Guides for fruit and vegetables from NYS IPM are a great place to start. When available, they report efficacy of OMRI-listed insecticides (including some bioinsecticides). Your local extension staff are another great resource.

How do they work? How do I use them? What do biofungicides add to vegetable disease management Part 2

rows of healthy winter squash plants with flags
Winter squash in our cucurbit powdery mildew biopesticide trial conducted in western NY, eastern NY, and on Long Island in 2018. We are also testing biopesticides for white mold. Photo credit: Meg McGrath.

Remember from Part 1 of this post that we (I and many great colleagues) are studying what biopesticides can add to effective disease management of cucurbit powdery mildew and white mold. After “what is a biopesticide?” the next most common questions about this project are about the specific biopesticides we’re testing:

  • How do they work?
  • Can I tank mix them with other pesticides or with fertilizers?
  • Do I need to use these products differently than I would use a chemical pesticide?

Today’s post will try to answer those questions.

 

Modes of action – How do they work?

As you may recall from February’s post, biopesticides work in different ways, and the five biofungicides we’re studying cover the range of these modes of action.

table summarizing modes of action for Contans, Double Nickel, LifeGard, Regalia, and Serifel
Biopesticides protect plants from diseases in different ways. I like to divide them up into the five modes of action (MOAs) in this table. Like many biopesticides, some of the products we are testing have more than one MOA. Click on the table to enlarge it.

Eats pathogen

The fungus active ingredient of Contans (Paraconiothyrium minitans strain CON/M/91-08; formerly called Coniothyrium minitans) “eats” (parasitizes and degrades) the tough sclerotia of the fungus, Sclerotinia sclerotiorum that causes white mold. Sclerotia survive in the soil from year to year. However, for this strategy to be effective, the fungal spores within Contans have to first make contact with the sclerotia. The time between colonization and degradation of sclerotia is about 90 days.

Makes antimicrobial compounds

The active ingredients in Serifel and Double Nickel are bacteria – same species but different strains. They both produce compounds that are harmful to plant pathogens (antimicrobial). According to the manufacturer, most of the foliar efficacy of Double Nickel is due to the antimicrobial compounds already present in the container. But the manufacturer notes that some of the efficacy also comes from the live bacteria that are responsible for this product’s other modes of action, especially the induction of plant resistance (more on this later). The strain of bacteria in Serifel has been formulated so that it contains only living bacteria (no antimicrobial compounds). The manufacturer’s goal is for the bacteria to produce antimicrobial products unique to the specific environmental conditions after application. Double Nickel and Serifel are examples of different strategies for using antimicrobial-producing bacteria to fight plant diseases. Our goal is to explain how the products work; not tell you which strategy is better.

smiling blue bacteria on a leaf; angry yellow bacteria have no place to land
Some biopesticides contain microbes that grow on the plant. These beneficial microbes use up space and nutrients so there is no room for the pathogen, excluding it.

Excludes pathogen

The bacteria in Double Nickel and Serifel also can protect plants from disease by growing over (colonizing) the plant so that there is no space or nutrients available for pathogens. How important this mode of action is to the efficacy of Double Nickel depends on the setting and time of year (according to the manufacturer). Cucurbit leaves exposed to sun, heat, and dry air are not great places for bacteria to grow, and pathogen exclusion is not likely to be very important in protecting cucurbit leaves from powdery mildew. The antimicrobial MOA is more important here. Apple blossoms being protected from fire blight in the early spring could be a different story. The bacteria in Serifel tolerate a wide range of temperatures in the field, but the manufacturer recommends applying this product with a silicon surfactant to help the bacteria spread across the plant surface better.

Induces plant resistance

Plants have mechanisms to defend themselves. Some pathogens succeed in causing disease when they avoid triggering these defenses, or when they infect the plant before it has a chance to activate these defenses. Some biofungicides work by triggering plants to “turn on” their defense mechanisms. This is called “inducing plant resistance.” It is the sole mode of action of the bacteria in LifeGard, and one of the modes of action for the active ingredients in Double Nickel, Regalia, and Serifel.

Promotes plant growth and/or stress tolerance

The last biofungicide being studied in this trial has a plant extract as an active ingredient, instead of a microorganism. Regalia works by both inducing plant resistance, and also promoting plant growth and stress tolerance. Some of the other products in this trial also share these MOAs. According to the label, some crops treated with Regalia produce more chlorophyll or contain more soluble protein. This final MOA (promotion of plant growth and stress tolerance) is also sometimes shared with “biostimulants”. But remember that “biostimulant” is not currently a term regulated by the EPA. This may be changing in the future, so stay tuned. Biostimulants enhance plant health and quality. They are not registered as pesticides, and must not be applied for the purpose of controlling disease. Make sure you read and follow the label of any product you apply.

Best practices – How do I use them?

We’ll get to some product-specific details in a minute, but first some notes about best uses for all five of these products.

  • They need to be used preventatively. For biofungicides to eat pathogens, exclude them from plants, induce plant resistance, or improve plant growth and stress tolerance, they need to beat the pathogen to the plant. It takes time for the plant to fully activate its defenses, even if “flipping the switch” to turn those defenses on happens quickly. The same applies to promoting plant growth and stress tolerance. And if you want the beneficial microorganism to already be growing where the pathogen might land, of course you need to apply the product before the pathogen is present. Microbes that produce antimicrobial compounds also work best if they are applied when disease levels are low.
  • Use IPM. These biofungicides (and most, if not all, biofungicides) were designed to be used with other pest management strategies like good cultural practices, host resistance, and other pesticides. For example, they can be included in a conventional spray program to manage pesticide resistance.
  • Mix what you need, when you need it. Don’t mix biofungicides and then leave them in the spray tank overnight. Some products may need to be used even more promptly. Check the label.
  • Store carefully. Generally, away from direct sunlight and high heat. Follow the storage instructions on the label.
  • They have short intervals, but still require PPE. One of the benefits of biofungicides is short pre-harvest intervals (PHIs) and re-entry intervals (REIs). All five of the products we’re studying have a 0 day PHI and a 4 hour REI. But they all still require personal protective equipment (PPE) when handling and applying them. Read and follow those labels!
  • Tank mixing best practices still apply. The table at the end of this post has details about biological compatibility of these products in tank mixes, as reported by the manufacturers. But just like other pesticides, you need to follow the label instructions for mixing. If you have questions about a specific tank mix partner, confirm compatibility with a company rep. Do a “jar test” if you are mixing two products for the first time and want to know if they are physically compatible.

Biopesticides (especially those that contain living microorganisms) often need to be handled and used differently than chemical pesticides. They may be more sensitive to temperature, moisture, or UV light, which may impact the best time or place to apply them. And of course you don’t want to tank mix a living microorganism with something that will kill the good microbe. (Cleaning your tank well between sprays is always recommended, whether or not you are using a biopesticide.) The following table summarizes details for the five products we’re studying provided by the manufacturers – from product labels, company websites, and conversations with company reps. We have not personally tested this information.

summary of FRAC codes, where and when to apply, temperature tolerance in the field, rainfastness, UV tolerance, tank mix compatibility, storage and shelf life for 5 biopesticides
Exactly how should you use these biofungicides to maximize their efficacy? This table summarizes best practices (as reported by the manufacturers) for each of the five fungicides tested in this trial. Click on the table to enlarge it.

We’ve created handouts that summarize the designs of both the cucurbit powdery mildew and the white mold trials, the modes of action of the five biofungicides we’re testing, and the best practices information presented above.

cucurbit powdery mildew biofungicide trial summary

white mold biofungicide trial summary

Stay tuned for Part 3 of this post – results from our first year of field trials!

 

This post was written by Amara Dunn (NYS IPM) and Sarah Pethybridge (Plant Pathology & Plant-Microbe Biology, School of Integrative Plant Science, Cornell University). Thank you to the New York Farm Viability Institute for funding.

A new resource to help you protect pollinators

honey bee is perched on top of a young developing squash with the flower still attached
Many crops (and plenty of non-crop plants) rely on pollinators. Let’s protect them!

As I’ve discussed before, the natural enemies that provide biological control of pests include both larger creatures (like insects, mites, and nematodes) and microorganisms (fungi, bacteria, and viruses) that combat pests in a variety of ways. Microorganism natural enemies are regulated as pesticides (one type of biopesticide), while the larger natural enemies are not. Growers who are successfully using biocontrol insects, mites, and nematodes usually recognize that they need to apply pesticides in such a way that they are compatible with the biocontrol organisms they use. Take a look at my April post for a summary of online resources that can help you check compatibility of pesticides (including biopesticides) with natural enemies.

Some of these compatibility resources include information on the effects of pesticides (and biopesticides) on bees. Pollinators (including honey bees, lots of other bees, and some non-bees) are very important beneficial insects. You may have noticed that they have found their way into several of my blog posts. So, I wanted to let you know about a brand new resource (hot off the digital presses) to help you protect pollinators.

Image of the cover of the resouces entitled: Pesticide decision-making guide to protect pollinators in tree fruit orchards
“A Pesticide Decision-Making Guide to Protect Pollinators in Tree Fruit Orchards” is a terrific resource to help you choose pesticides (and pesticide combinations) that are least-toxic to bees.

A Pesticide Decision-Making Guide to Protect Pollinators in Tree Fruit Orchards” was written by Maria van Dyke, Emma Mullen, Dan Wixted, and Scott McArt. Although it’s focus is tree fruit orchards (and therefore the pesticides used in them), it should be useful for growers of other crops who want to choose pesticides that are least toxic to bees. A few highlights:

  • It includes information not only on pesticides used alone, but (when available) on synergistic effects when multiple pesticide active ingredients are used together. When you combine some chemicals (either in the tank or in the environment) the mixture is more toxic than both chemicals alone.
  • Where available, it summarizes pesticide toxicity to other bees besides just honey bees (e.g., bumble bees and solitary bees). You can read more about why this is important in this recent article.
  • It describes what we know about sub-lethal (in other words, negative effects on the bees that are less serious than death) effects of pesticides on bees.
  • It includes about half a dozen biopesticide active ingredients.
bumble bee feeding on a purple flower
Pollination is being done by more than just honey bees! This bumble bee (plus many more bee species) are important pollinators in NY.

You might be asking: If a chemical on this table is toxic to bees, will it also be toxic to the insect and mite natural enemies I am releasing or conserving on my farm or in my garden? I wish I had a definitive answer to that. As you can see from the nearly three pages of Literature Cited at the end of this document, collecting these data is a time-consuming process. For now, stick with the compatibility resources that are already available, and ask the companies you buy from (pesticides or natural enemies) about compatibility.

In closing, a huge amount of work went into this resource to summarize so much useful and current (as of October 2018) information in an easy-to-read table. Bravo to the authors! The Pollinator Network @ Cornell has other helpful resources for growers on protecting pollinators. Winter is a great time to make plans for using IPM and protecting the pollinators and natural enemies that are so good for the crops we grow!

Creating habitat for beneficial insects: Project update at the end of the first year

Fair warning, this is going to be a longer post. But partly that’s because there are so many pictures. I will start with the overview, then go a bit deeper into the weeds (literally and figuratively). To help you navigate more quickly, here’s a sort of table of contents that will quickly take you to the information you may be most interested to read:

Overview

Details on weed control

Timing of fall planting

The steps we followed to establish beneficial insect habitat

mixed wildflowers in a field
Some of our beneficial insect habitat plots looked really beautiful this fall! Others are still works in progress.

Overview
Remember back in June when I told you about the different techniques we were comparing for establishing habitat for beneficial insects? Time for an update! Here’s a brief, two-page summary of the first year of this project. For all the juicy details (and lots of pictures), keep reading!

First, remember that when I say “beneficial insects”, I mean both pollinators and natural enemies of pests. (Technically, arthropod would be a better term than insect, because spiders and predatory mites are some of the beneficial creatures we’d like to attract.) Fortunately, the same type of plants provide food and shelter for both pollinators and natural enemies on your farm or in your garden.

We used six different techniques to establish this habitat during Spring, Summer, and Fall of 2018. Treatment E was our control, where we did nothing but mow (after initial herbicide applications).

Treatment Fall 2017 Spring 2018 Summer 2018 Fall 2018
A Herbicide Herbicide, transplant  Weed 2x Replace dead plants
B Herbicide Till, transplant, mulch Weed 2x Replace dead plants
C Herbicide Till, direct seed Mow 3x Mow 1x
D Herbicide Till, plant buckwheat Mow 1x, till, plant buckwheat Mow 1x, transplant
E – control Herbicide Herbicide Mow 3x Mow 1x
F Herbicide Till, lay plastic Continue solarization Remove plastic, direct seed
G Herbicide Herbicide/till Herbicide 2x, till 1x Till 1x, direct seed

We transplanted the following species in treatments A, B, and D:

Common name Scientific name Number of plants in each 5 x 23 ft plot
Anise hyssop Agastache foeniculum 2
Common milkweed Asclepias syriaca 3
Blue false indigo Baptisia australis 2
Lanced-leaved coreopsis Coreopsis lanceolata 3
Purple coneflower Echinacea purpurea 2
Boneset Eupatorium perfoliatum 3
Wild bergamot Monarda fistulosa 2
Catmint Nepeta faassinii 2
Tall white beard tongue Penstemon digitalis 3
Black-eyed Susan Rudbeckia fulgida va. Fulgida 1
Little bluestem (grass) Schizachyrium scoparium 11
Showy goldenrod Solidago speciosa 1
New England aster Symphyotrichum novae- angliae 3
Ohio spiderwort Tradescantia ohiensis 2
NY ironweed Vernonia noveboracensis 2
Golden alexanders Zizia aurea 3

We planted seeds in treatments C, F, and G. The seed mixture we used was the Showy Northeast Native Wildflower & Grass Mix from Ernst Seeds, which included a more diverse species mix. This mix changes a bit from year to year. If you’re interested, you can learn about the details of the specific mix we used here.

 Labor and costs

Not surprisingly, there were big differences in how much time and money we spent on different treatments this first year. The costs and hours below are for a total area of 460 ft2 (0.01 A) per treatment. Most of the cost differences are due to the huge difference in seed versus transplant expenses. We paid about $2 per plant and needed 180 plants for each treatment. In contrast, we spent about $12.50 on seed for each treatment. You can find itemized lists of cost and time inputs for each treatment here.

Treatment Supply costs Time (person hrs)
A – spring transplant $417.12 13.2
B – spring transplant & mulch $539.29 20.4
C – spring seed $17.75 4.4
D – buckwheat & fall seed $390.55 10.3
E – control $2.32 2.6
F – solarize & fall seed $148.02 10.2
G – herbicide/tillage & fall seed $22.04 6.3

But, there were also big differences in how quickly the plants established. By September, both treatments (A and B) that had been transplanted in the spring looked like well-established gardens, with large, blooming wildflowers.

Transplanted plots with more weeds (left) and fewer weeds (right). Plot on the right had been mulched.
Four and a half months after transplanting, the beneficial habitat plants in treatments A (left) and B (right) were mostly growing well. But there was a big difference in weed control, in spite of similar amounts of time spent weeding each treatment.

We were generally pleased by how well most of the spring transplants survived. Although all the transplants came in 50-cell flats, some were larger than others, and the larger transplants survived better. We were fortunate to be able to plant into nice moist ground, so except for a little water on the day of transplanting, we didn’t irrigate. Survival might not have been as good if we’d had different planting conditions.

In contrast, the much less expensive treatment C was not looking too impressive even by October. A few partridge peas and blackeyed Susans bloomed this year, but otherwise it didn’t look much different from the control plots. In mid-summer, it looked like we were growing more ragweed than wildflowers.

Mower cutting ragweed (left) and mowed weedy mix with a few yellow flowers blooming.
In late July, it looked like we were growing mostly ragweed in treatment C (left). But after mowing four times during the summer and fall, you could definitely see the blackeyed Susans establishing (right).

Two of the treatments (F and G) were planted with seeds this fall, and one treatment (D) was transplanted this fall. So it’s really too early to tell how successful those treatments were. Stay tuned for more updates!

Mixture of mowed weeds with small plants (left), plot of bare ground (middle and right)
Fall transplanted (D) or direct seeded treatments (F and G) did not look very impressive by October 19, 2018. I’m curious to see what they look like next spring, summer, and fall!

Details on weed control

What about weeds? The graph below shows the average percent of the surface area of each plot that was covered with weeds versus planted beneficial habitat species on September 19, 2018. (Thank you, Bryan Brown, NYS IPM Integrated Weed Management Specialist for doing a weed assessment for us!) While we spent about the same amount of time weeding treatments A and B (the time difference is due to the time spent mulching treatment B), we achieved much better weed control with the mulch than without it!

Bar graph showing how much of each plot area was covered by weeds and by beneficial plants for each treatment
Bryan Brown assessed the percent of each plot that was covered with either the beneficial habitat species we had planted (blue) or weeds (orange). Each bar represents the average of four plots for each treatment, and the error bars show the standard error.

In treatment B, we spread chipped shrub willow mulch about 3 inches deep around the transplants. If I were to do this again, I would spread it thicker. I was disappointed with how many weeds were growing through the mulch just a month after transplanting.

mulched plot with lots of weeds on the left and fewer weeds on the right
The chipped shrub willow mulch we used was not as effective at suppressing weeds as I had hoped. On the left is part of the plot that had not been weeded yet. On the right is the part that was weeded on July 6. You can also see from this picture that there was a lot of lambsquarters in this field, and that we hadn’t been able to seed grass between the plots, yet.

But weeding twice during the season pretty much took care of the weeds in treatment B. Treatment A was also weeded twice, but as you saw in the graph earlier, weed control by the end of the season was not as effective.

Unmulched plot weeded (on the left), and before weeding (on the right)
Treatment A (transplanted in the spring, with no additional weed control) before (right) and after (left) hand weeding on July 6.

I think we’ll have to wait until next year to really understand how weed control is working in treatment C. Remember, the strategy was to slowly deplete the annual weed seedbank by allowing weeds to germinate, but preventing them from producing more seed. This is not supposed to be a quick establishment method, and it wasn’t.

blooming yellow flower (partridge pea)
This is what partridge pea looks like. It was one of the few species from the native wildflower and grass mix seeded in the spring (treatment C) that bloomed during this first growing season.

Buckwheat as a weed-smothering cover crop

By the time Bryan did our weed assessment, it had been 3 weeks since we mowed the second planting of buckwheat. Ideally, we would have transplanted shortly after mowing the buckwheat. But, the second crop of buckwheat was starting to set seed by the end of August, and our transplants weren’t scheduled to arrive until the end of September. So we mowed the buckwheat early to prevent it from contributing its own seed to the weed seedbank. But this meant that a lot of weeds had time to germinate before we transplanted the habitat plants. The buckwheat certainly suppressed a lot of weeds during the growing season, and I hope that this will help reduce weeds next year.

very young buckwheat seedlings in upper left, larger buckwheat seedlings in upper right, mowing mature buckwheat plants in lower left, cut buckwheat stubble in lower right
The buckwheat established quickly and crowded out many weeds. We mowed the first crop in July and re-planted. We had to mow the second crop about 3 weeks before we transplanted habitat plants (not ideal).

Solarization

Overall, we were pleased with how the solarization worked. We laid down 6 mil clear plastic (leftover from a nearby high tunnel) in early June, and did a little weed control around the edges of the plastic just once during the summer to prevent more weed seed production and to prevent shading of the plots.

Two people shovelling soil on top of clear plastic laid on the ground on the left, and on the right, clear plastic cover a small area of soil, with all the edges of the plastic buried
We laid 6 mil clear plastic over some plots on June 5, 2018 to solarize the soil underneath (and kill weeds).

We also learned that solarization will not control purselane. In contrast, the purselane thrived only under our clear plastic, and nowhere else in the field. The plot that had the most purselane also had the most other (mostly grass) weeds. I think the purselane pushed the plastic away from the soil and reduced the temperature a bit, allowing other weeds to grow.

clear plastic covering a small area of soil, but with weeds (purselane) growing underneath it
In some solarized plots, purselane grew happily under the plastic. Purselane was not a common weed anywhere else in the field during the season.

Some other plots were virtually weed-free when we pulled the plastic up in October. (Did you see how large the error bar was for weeds in treatment F in the weed graph above? This means there was a lot of variability between plots in this treatment.) Our soil temperature probe happened to be in the plot with the most purselane, and we still achieved maximum soil temperatures of 120 °F (at a depth of about 3 inches), compared to 90 °F in a nearby control (treatment E) plot.

Plots of ground that had been covered with clear plastic. On the left, very few weeds grew underneath. On the right, more weeds (purselane and some grasses) grew.
Solarization results were pretty variable from plot to plot. In some plots, it worked great (left). In other plots more purselane germinated and it didn’t work as well (right). We cut all the weedy vegetation off at the ground before direct seeding the beneficial habitat plants.

Repeated herbicide and tillage

At the weed assessment in September, the plot that had been alternately treated with herbicide and tilled looked best in terms of weed control. Like treatment C and all the treatments planted (by seed or by transplant) in the fall, I think we’ll get a better idea next year of how effective this method was at suppressing weeds.

A small plot of mostly bare soil with a few small weeds growing through. The plot is surrounded by grass
A few weeds were present a week after the last time the herbicide/tillage treatment (G) was rototilled. We broadcast, raked, and pressed beneficial habitat seed into these plots.

Timing of fall planting

One thing we struggled with this fall was deciding when to plant the wildflower and grass seed mixture. One source recommended the seeds be planted sometime between October and December. We were cautioned that if we planted the seed too early, some species (especially blackeyed Susans) might germinate this fall, and the young seedlings would be killed by an early frost before they established. But we were also afraid of waiting too long and not being able to till the soil (treatment G, only) if it got too wet. And we wanted a nice smooth seedbed. In treatment F, we suspected that leaving the clear plastic on into November would protect the weeds from the cooler weather. But we worried that taking it off too early would only allow more weed seeds to blow onto the bare ground.

person dressed in warm clothes sprinkling seed on bare ground. There is a field and a pond in the background.
We direct seeded October 18, 2018, after the weather cooled down a bit, and before the ground got too wet.

Finally, we compromised and planted the seeds on October 18 and 19, after our first hard frost, and once it looked like the nighttime temperatures would be in the 40’s (or below) for the next 10 days. It was only a week after the last tillage in treatment G, and the soil was still relatively dry. Those who live in the Finger Lakes know that late October and early November were pretty wet this year, so I’m glad we planted when we did. If you are trying to time fall seeding, I would recommend that you keep an eye on the 10 day forecast to see when temperatures are starting to cool. But if you get a dry sunny day to plant and it’s reasonably cool, I wouldn’t delay.

So if I want to plant habitat for pollinators and natural enemies next year, what should I do?

First, think about the time, money, and equipment you have available, as well as the area you’d like to plant. There probably isn’t a single right way to establish this habitat, but there may be a best way for you.

You can find more details on the techniques we used (and some links to other resources) here.

This post was written by Amara Dunn, Brian Eshenaur, and Betsy Lamb.

This work is supported by the Crop Protection and Pest Management Extension Implementation Program [grant no. 2017-70006-27142/project accession no. 1014000] from the USDA National Institute of Food and Agriculture.

Biocontrol info from NYS IPM

Skip to toolbar