Category Archives: field crops

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.

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).

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.

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.

Creating habitat for beneficial insects – early summer 2018 project update

Betsy, Deb, and Brian transplanting native wildflowers and grasses that will provide habitat for beneficial insects
Dr. Betsy Lamb, Deb Marvin, and Brian Eshenaur (left to right) transplanting native wildflowers and grasses on the edge of a research Christmas tree planting at Cornell AgriTech in Geneva, NY. These plants will provide food and shelter for pollinators and natural enemies of pests.

As I mentioned in my January post, I am excited to be working with two NYS IPM colleagues (Dr. Betsy Lamb and Brian Eshenaur) to demonstrate the costs, labor, and effectiveness of different methods for establishing habitat plants for pollinators and other beneficial insects. Remember, habitat for pollinators is also habitat for insects and mites that are natural enemies of pests on your farm or in your garden. Thus, planting for pollinators enables you to practice conservation biocontrol. These demonstration plots are located around a new research planting of Christmas trees at Cornell AgriTech at the New York State Agricultural Experiment Station in Geneva, NY. What we learn from this project can help you choose the best way to establish your own beneficial habitat (on your farm, around your home, near your school, etc.)

We are comparing 6 different methods of establishing habitat for beneficial insects, plus a control (Treatment E). Treatment E plots were sprayed with herbicide last fall and this spring, and will be mowed once this year. A summary of the plan for the other treatments is below.

List of treatments in this study. Each treatment is a different method for establishing habitat for beneficial insects
Comparing different methods for establishing plants that provide habitat and food for beneficial insects (pollinators and natural enemies of pests). Treatment E is the control.
seeds for plants that will provide habitat for beneficial insects
Native wildflower and grass seeds (A) were mixed with boiled rice hulls (B) to make them easier to broadcast (C). Much of what you see on the soil surface is just the rice hulls, but there are a few seeds that will hopefully grow into habitat for beneficial insects.

Because of when spring tillage occurred, plots that were scheduled to be tilled in the spring did not need a second herbicide application. About a week after spring tillage, Treatment C plots were direct seeded. I hand-broadcast a mixture of native wildflower and grass seeds at a rate of half a pound per 1,000 square feet. This worked out to be 26 g of seed for each 5-foot by 23-foot plot. To make it easier to broadcast such a small amount of seed, I first mixed the seed for each plot with about 3 cups of boiled rice hulls. After raking the seed in gently with a garden rake, I stomped the seed into the ground to ensure good contact with the soil. In a larger plot, you might use equipment like a cultipacker or lawn roller to achieve the same result.

 

young buckwheat plants
Two weeks (and three-quarters of an inch of rain) after seeding, buckwheat is establishing. It will hopefully crowd out weeds that would otherwise grow in these plots over the summer.

I broadcast (again, by hand) buckwheat seeds in the Treatment D plots at a rate of 70 pounds per acre (84 g for each of these small plots), and raked them in on May 31st. If the buckwheat establishes well, it will smother weeds during the summer, and we can mow and transplant into these plots in the fall. We plan to mow this crop of buckwheat when it starts flowering and then reseed it, for a total of two buckwheat plantings this summer.

 

We transplanted by hand 15 species of wildflowers and 1 grass species into plots assigned to Treatments A and B on June 4th. Because we were able to transplant right after it rained, it wasn’t too difficult to plant into the untilled plots (Treatment A). Some of them still had some stubble from the cover crops and weeds that had been growing in this field last year, and were killed by fall and spring herbicide applications.

Young wildflower and grass plants transplanted into untilled soil.
Native wildflowers and grasses transplanted into untilled soil. Some dead weeds and cover crop still remain on the soil surface.

The day after we transplanted into Treatment B plots, we mulched the plants to a depth of about 3 inches to (hopefully) control weeds for the rest of the summer while the habitat plants get established. We used chips from shrub willow because they were available, but other types of mulch would work, too.

wildflower and grass plants surrounded by mulch for weed control
These wildflowers and grasses will have help out-competing weeds from 3 inches of willow chip mulch.

Finally, we laid clear high tunnel plastic over the plots receiving Treatment F. Ongoing research from the University of Maine suggests that soil solarization can be an effective form of weed control, even in the northeast. So we’re giving it a try! To maximize the efficacy of this technique, we laid the plastic when the soil had been tilled relatively recently, and was still very moist. To keep the plastic firmly in place for the whole summer, we rolled the edges and buried them 4-5 inches deep, then stomped the soil down around all the edges. In the fall, we will hand broadcast a mixture of native wildflower and grass seeds over these plots (same mix as Treatment C).

a trench being dug around the edge of a plot to bury the edge of a sheet of clear plastic
Deb Marvin and Brian Eshenaur (left to right) dig a trench to bury the edge of this sheet of clear plastic. The goal is weed control by soil solarization.

We’ll give weed seeds in the Treatment G plots a few more weeks to germinate and grow (depending on the rain). Then we’ll kill them with an herbicide, and till these plots again to induce more weed seeds to germinate. Then we will repeat the herbicide application, till again, and so on. This should reduce the weed seed bank in the soil over the course of the summer. After a final tillage in the fall, we will broadcast seed from the same wildflower and grass mix we used for Treatment C. Fall is the recommended time for direct seeding beneficial insect habitat in the northeast. This treatment will also have the advantage of a full season of weed control prior to planting (also recommended). The downside is that it will take longer to establish the beneficial insect habitat.

As we get these plots established, we’re keeping track of the time spent on each treatment and the costs of materials. In the late summer or fall, Dr. Bryan Brown will assess weeds in each treatment, and I will photo document how well our beneficial insect habitat plants have established in each plot. All of these data will help you choose the method that fits your timeline, budget, and equipment/labor availability. Stay tuned for more updates…including an invitation to a field day (not this year), so that you can come see the results of this project for yourself!

Mix and Match: Compatibility of biocontrol with other pest management strategies

Delphastus eating whitefly
This small black Delphastus is helping to control whiteflies in a greenhouse. It’s important that other pest management strategies in this greenhouse are used in such a way that they do not harm the Delphastus.

If you were going to tank mix chemical pesticides, you would of course read the label to check for compatibility before mixing products. The same concept applies when using living organisms for pest control. Whether you are using parasitoid wasps, predatory mites, microorganisms, or nematodes, you need to know whether your biocontrols are compatible with each other and any other pest management products you plan to use. For example, a biocontrol fungus might be killed if you tank mix it with (or apply it just before) a chemical fungicide. Insecticides (whether or not they are biological) could be harmful to natural enemy insects and mites. Even some beneficial insects are not compatible with each other because they may eat each other instead of (or in addition to) the pest.

It’s a good idea to keep an updated list of the products and organisms you plan to use for pest management, and their compatibility with each other. For biopesticides (remember the difference between “biopesticide” and “biocontrol”?), start by reading the label (see label excerpt below). You must follow all instructions you find there. Many manufacturers also provide lists, tables, databases, or apps to help you find compatibility information (some links at the end of this post). This is especially useful for insect, mite, and nematode natural enemies, which are not pesticides and do not have pesticide labels. When possible, obtain compatibility information from the manufacturer or supplier you will be using. Different strains of the same microorganism or nematode may have different sensitivities to chemicals.

Compatibility information from Preferal label
This excerpt from the label of the bioinsecticide Preferal provides some information on its compatibility with other products. All instructions on a pesticide label must be followed.

Remember that NY pesticide labels (including biopesticide labels) can be found through the NYSPAD system.

Below are some links to resources from several manufacturers and suppliers of biocontrol products. No endorsement of specific companies or products mentioned in this post is intended. If you know of a link to additional information that is missing, please let me know so that I can include it!

Beneficial nematodes from BASF – This chart describes compatibility of beneficial nematodes sold by BASF with natural enemies and pesticides. Note that only the genus name of each “biological” active ingredient is listed, and that over time, the names of some predatory mites (and whether they belong to the genus Amblyseius or Neoseiulus) have changed.

BASF table describing compatibility
Screen shot of part of a table summarizing compatibility of BASF beneficial nematodes with other pest management tools (in this case, biocontrol insects and mites).

 

Biobest Side Effect Manual – This side effects manual is available either as an interactive website, or as an app. Choose pest management products by active ingredient or name of the commercial product (including the biocontrol microorganisms Beauveria bassiana and several types of Bacillus thuringiensis). The list of “beneficial organisms” to choose from includes bumble bees and nematodes, but not beneficial microorganisms (fungi, bacteria, and viruses). Select active ingredients/commercial products and beneficial organisms from both lists, then use the legend to interpret the compatibility information that is generated.

 

Compatibility of BioWorks products – Compatibility sheets are linked from each product page.

BioWorks compatibility information
A portion of one of the compatibility sheets provided by BioWorks for their products.

 

 

 

 

 

Koppert Side Effects Information – This information is available either as an interactive website, or as an app. Select beneficial organisms of interest (by either the Koppert product name or the Latin name). Select one or more “Agents” (pest management products) by either the trade name or the active ingredient. Click on Results, and use the Legend to interpret the output.

Koppert compatibility information
Screen shot from the web-based version of Koppert’s compatibility resource.