September 21, 2017

NYS IPM Weekly Field Crops Pest Report: September 21, 2017

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Volume 16 Number 20

Mechanical Cultivation Equipment Demo Day

Tuesday, October 3 at 1 PM – 4:45 PM

371 Big Island Road Goshen, NY 10924

View from the Field

There have been a lot of reports of white mold (Sclerotinia stem rot) in soybeans across the state. For more information on white mold see the previous published article: White Mold Sclerotinia Stem Rot in Soybeans

 

White Mold on Soybeans

Many consultants and extension educators are reporting minor northern corn leaf blight and gray leafspot infestations in corn. Some of the brown mid-rib corn hybrids have had heavy infestations of gray leaf spot in the Hudson Valley.

 

Gray Leafspot on Corn

There are reports of western bean cutworm infestations in ears of field corn in the Hudson Valley. While they most likely are not over an economic threshold the presence of larger infestations of western bean cutworm in the Hudson Valley is a sign of increasing populations of the pest in the years to come.

WBC larva in corn ear tip

Weather Outlook – September 21, 2017

Jessica Spaccio

NOAA Northeast Regional Climate Center, Cornell University

 

Last week temperatures ranged from 4-10°F above normal. Precipitation ranged from less than ¼” to 3 inches, with most areas seeing less than ½”. Base 50 growing degree-days ranged from 80 to 160.

Warm, sunny, and generally dry through next week, but watching Maria…

Today and Friday expect mostly sunny to partly cloudy skies with highs in the mid 70s to mid 80s. Overnight lows will range from the mid 50s to the mid 60s, with cooler temperatures likely in the Adirondacks.

For Saturday through Monday highs will be in the 80s for most areas. Expect mostly sunny to partly cloudy skies. Low temperatures will generally be in the mid 50s to the mid 60s.

 Tuesday highs will range from the mid 70s to mid 80s. Expect mostly sunny to partly cloudy skies. Lows will be in the mid 50s to mid 60s.

Wednesday will be mostly sunny to partly cloudy skies, with a chance of scattered showers. Highs will be in the low 70s to low 80s.

The seven-day precipitation amounts from yesterday through next Wednesday (Sep 20-27) will range from less than 0.01” to ½ ”, with the greatest amounts across eastern Long Island.

The 8-14 day outlook (Sep 28-Oct 4) shows near-normal temperatures are expected for the entire state. Below-normal precipitation is slightly favored for western New York, above-normal precipitation is slightly favored for northeastern New York, and near-normal precipitation is expected for the rest of the state.

Maps of 8-14 day outlooks:

http://www.cpc.ncep.noaa.gov/products/predictions/814day/index.php

National Weather Service watch/warnings map:

http://www.weather.gov/erh/

US Drought Monitor:

http://droughtmonitor.unl.edu/Home.aspx

CLIMOD2 (NRCC data interface):

http://climodtest.nrcc.cornell.edu

Stalk Rots in Field Corn?

Ken Wise, NYS IPM

 Stalk rots are normally a complex of different diseases and factors working in the corn plants. Many times stalk rots occur when you have multiple stresses on the corn plants at the same time over the course of the growing season. This could be the combination of environmental factors, soil nutrition, diseases, insect pests, available moisture and more. When a plant is stressed in more ways than one it is more vulnerable to diseases like stalk rots. There are many different fungi and bacteria that can cause stalk rots. Many of these diseases can survive on past corn crop residue or even in the soil. Stalk rots normally enter the plant through the roots but can enter other ways like insect pests boring into the stalk leaving an open hole for pathogens to enter the plant through wind or rain. Stalk rot causes premature death of the corn plant by attacking water conducting tissues of the roots and lower stalks. As it progresses the fungi moves up the pith of the plant. The cells in the pith of the plant are thinner and much easier for the disease to attack than from the outside. This limits the plant from moving water and nutrients. The rot will weaken the stalks and plants can start to lodge. While each species of stalk rots have specific symptoms they do have a few that are in common.

  1. Leaves may be wilted or roll and start to turn brown.
  2. An entire field may appear to be killed by a frost because the disease does not allow water and nutrients to move through the plant
  3. Lesions will appear on lower nodes and/or on entire stalk
  4. Stalks become soft (healthy stalks are firm). With advance stages of rot the stalk can be easily crushed with your fore finger and thumb.
  5. Stalks can lodge with a weather event.

 

The following are specific types of stalk rots found in NYS:

Common Name/Species Symptoms Link to photos
Anthracnose stalk rot/ Colletotrichum graminicola Symptoms often show after tasselling as vertical, tan to reddish brown, water-soaked lesions (streaks) in the stalk rind. Lesions become large and dark brown to shiny black. If you see anthracnose leaf blight, check for anthracnose stalk rot—both diseases share the same causal agent.

Anthracnose stalk rot

 

Diplodia stalk rot/ Stenocarpella maydis Symptoms appear as numerous black pycnidia (a saclike spore case) in the lower internodes of the stalk. The cases are black dots size of a pinhead or smaller. Look for a white mold on the stalks when weather is wet Diplodia stalk rot
Fusarium stalk rot/ Fusarium spp. This disease normally starts just after pollination, with symptoms appearing later in the season. When you cut open the stalk, the pith shows as a whitish to pink (salmon) color. Look also for distinctive brown streaks on the lower internodes.

Fusarium stalk rot

 

Gibberella stalk rot/ Gibberella zeae This disease shows first as leaves fade to a grayish-green. Stalks turn dark green to tan near their bases. The pith softens, turning reddish or pink Gibberella stalk rot
Pythium stalk rot/ Pythium aphanidermatum This disease normally appears as a decay of the first internode above the soil. The pith will become soft, turn brown and appear water-soaked. Many times the stalk can twist and/ or lodge. Even though it may have lodged the plant will stay green for several weeks because the vascular tissue is not destroyed.

Pythium stalk rot

 

 

There are management practices you can do to limit corn stalk rots in your fields.

 

  1. Plant hybrids that are resistant to the diseases. Remember that corn can be resistant but never immune.
  2. Use of crop rotation is a good way to limit the diseases from infecting the corn. Many of these diseases survive on corn residue. By planting corn in the same field each year you increase the risk of getting an infection.
  3. Use proper plant populations. If a field is planted at too high of a population the corn will compete for nutrients and water. This adds more stress to the plant and an increased risk of getting an infection.
  4. Maintain good soil fertility and pH. By maintaining good soil fertility and pH helps keep corn plants healthy and reduces stress on the plants.
  5. Proper cultivation. If you cultivate, it is important not to damage the roots or the plants. If they are damaged it increase the pathways for disease to infect the plants.
  6. Tillage can help reduce the available disease in the field by burying residue. While tillage can help it is not a guarantee control. Plus the need to reduce erosion and save on soil moisture maybe more important.

What is on Your Corn Ears!

Ken Wise, NYS IPM

Have you seen mold in your ears of corn? It is a good time to check for corn ear rots before harvesting silage or grain. Ear rots can cause issues for you later. The first thing is that it can reduce the quality of the corn you are harvesting. The second thing is that certain kinds of ear rots (fungi) can produce mycotoxins. These can be harmful if not fatal to livestock. The third is that ear rots can continue to develop into a problem if grain or silage is stored with an infection. Some of the factors that help contribute to ears becoming infected are susceptible hybrids, birds pealing the husk back exposing the ear, insect pest like western bean cutworm feeding on the ear of corn or European corn borer making holes. These factors expose the ear to fungal spores that may attack the kernels.

How do you know if you have a problem?

Check 100 ears of corn. If you have 10% of the ears with fungi that cover more than 25% of the surface area early harvest should be considered.

Identification of disease

It is important to correctly identify which ear rots you may have. Some ear rots produce toxins. Ear rots that can potentially produce toxins do not always do so. If you can identify the disease you make better decisions on what to do. If you happen to identify a disease that can produce a toxin you can send a sample for testing to confirm or not whether it has a toxin. The following are types of ear rots we can get in New York:

 

Fusarium Ear Rot (Fusarium moniliforme or Fusarium verticillioides) This disease appears as a white-to-pink or salmon-colored mold. This mold can begin with bird, deer or insect-damaged kernels. Fusarium ear rot may contain fumonisins which are mycotoxins that can be toxic to livestock. Fusarium Ear Rot
Gibberella Ear Rot/Gibberella zeae (Fusarium graminearum)

The symptoms are pink to reddish colored mold. This disease starts near the tip of the ear and progresses down toward base of the ear. Gibberella can produce vomitoxin and zearalenone which is toxic to many kinds of livestock.

 

Gibberella Ear Rot
Diplodia Ear Rot (Stenocarpella maydis)

The symptoms appear as a thick white mold that usually starts near the base of the ear. This disease can also appear on the plant as raised black fruiting bodies on moldy husks or kernels. Diplodia does not produce any known toxins.

 

Diplodia Ear Rot
Cladosporium Ear and Kernel Rot (Cladosporium herbarum or C. cladosporoides)

The symptoms appear as greenish black, blotched or streaked kernels scattered over the ear. This disease can also infect kernels that have been damaged by insects, birds, deer, hail, or frost. The disease can progress after the grain is harvested and stored.

 

Cladosporium Ear and Kernel Rot
Penicillium Ear Rot, Aspergillus Ear rot or blue eye (Aspergillus spp. and Penicillin spp.)

The symptoms range from a powder-like green or blue-green mold that is on and between the kernels and normally on the tip of the ear. If this disease progresses in storage it is referred to as blue eye because the germ is a bluish-green color. Penicillium ear rot can produce a mycotoxin called “ochratoxin”.

 

Penicillium Ear Rot, Aspergillus Ear rot or blue eye

 

 

What can be done to control future ear rots?

  1. Grow resistant hybrids well adapted for your location. Note that no hybrid is 100% resistant but will have much less infection than hybrids that are susceptible.
  2. Rotate Fields. Corn after corn allows fungi to overwinter on crop residue. This increases the risk of infection the next year; especially under conservation tillage.
  3. Good soil fertility. Proper soil fertility and pH creates healthy plants and reduces stress, thus reduces the risk of ear rots
  4. Good insect pest management reduces stress on the plant and risk of infection
  5. If you are harvesting corn grain make sure you clean the grain bins. Keeping the proper temperature, moisture content and good aeration in the grain bin can reduce storage molds from developing. It is important to have regular inspections of the stored grain. This is essential to minimize risk of developing insect and mold associated storage problems.
  6. Harvest silage at recommended maturity and moisture level, and pack silage tightly and exclude air rapidly. Consider using organic acid preservatives if you can’t exclude air or reduce moisture. If you had a lot of stalk rot and were growing for grain consider chopping earlier for silage to minimize lodging and combine losses.
  7. There are kits you can purchase to test your corn for different toxins on your own farm. The following is where you can also test your corn: Dairy One Forage Lab

 

Degree Days for New York State

Clipboard Checklist

Keith Waldron, NYS IPM

 General

*Walk fields to check general field condition, weed, vertebrate and other issues

*Watch for crop maturity, stand assessments, weed escapes, nutrient deficiencies, lodging issues

*Update crop records and field history

 

 Alfalfa:

*Evaluate established legume stands for approximate days until harvest
*Monitor potato leafhopper, foliar, systemic and crown rot diseases.
*Monitor new seedings for potato leafhopper, pythium blight, phytopthora root rot.

Small Grains:
*Monitor grain fields for growth stage, disease and lodging issues, grain maturity, harvest timing
*Record diseases present, location and types of weed escapes

*Prepare for planting winter small grains after the Hessian Fly Free Date.

 

Corn:

*Monitor for mid-season corn pests including European corn borer, corn rootworm, western bean cutworm, slugs, foliar diseases such as northern corn leaf blight and gray leaf spot, weed issues, nutrient deficiencies, vertebrate damage.

 

 Soybeans:

*Monitor for growth stage, soybean aphid, defoliators, foliar diseases, white mold, weed issues, vertebrate damage

*Record diseases present, location and types of weed escapes

 

 Pastures:

*Check water sources, mend fences as needed.
*Check crop growth, clip pastures between grazing as needed
*Monitor for invasive species, plants harmful to livestock
*Review/Plan rotations

 

Storage:

* Check stored grain bins for temperature, moisture and signs of mold and insects. Aerate, core, transfer grain or treat as necessary

* Clean and disinfect empty storage bins in preparation for grain harvest
*
Check forage allocation and anticipate feed program adjustments as forages from previous year are used up
*Mow around storage bins and facility to minimize pest hiding places

 

Dairy Cattle Barn Fly Management:

*Monitor animals and barn area for house fly, stable fly and other pest management needs including presence of rodents and birds.
*Check facilities for favorable fly breeding conditions: (organic matter + moisture): leaks in watering systems, roof gutters for leaks and potential overspill, drainage,
*Sanitation, sanitation, sanitation – clean animal resting areas, feed troughs, minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard
* Continue fly monitoring: install “3X5″ index card fly speck monitoring cards throughout barn
*Use, replenish, replace fly management materials: sticky fly tapes/ribbons, insecticide baits, natural enemies (parasitoids), fly population monitoring (3 x 5) spot cards
*Consider purchase and release of Muscidifurax raptor and/or M. raptorellus natural enemies of house and stable fly pupae.

 

Dairy Cattle on Pasture:

*Monitor animals for presence of face flies, horn flies and stable flies. Action guidelines: face flies (average 10 per animal face), horn flies (average 50 / dairy per animal side, 200 / beef cattle per animal side), stable flies average 10 per animal (all four legs)
*Check feed bunk / water source locations for signs of stable fly breeding (moist undisturbed organic matter – spilled feed, round bales, etc.), minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal exercise yard.
*Check pasture for forage quality / quantity, rotate as appropriate
*Check pasture for vegetation poisonous to livestock
*Consider use of pasture fly traps to help reduce deer, horse and stable fly populations