May 31, 2013

NYS IPM Weekly Field Crops Pest Report, May 31

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In this issue:

  1. View from the Field
  2. Weather Outlook
  3. Quantifying Row Crop Plant Populations
  4. Fusarium head blight update
  5. Spring Related  Alfalfa Diseases
  6. Growing Degree Days
  7. Clipboard Checklist

View from the Field

There are many reports of alfalfa weevil (AW) over the threshold in alfalfa this week. The threshold for is cutting is 40% tip feeding by AW larvae. The second cutting threshold is 50% tip feeding on regrowth.

Extreme Alfalfa Weevil Damage

There are continued reports of cereal leaf beetle in small grains this week. We have found small to moderate levels of cereal leaf beetle in Columbia and Ulster Counties in triticale.  These fields were far below threshold. In Western NY some winter wheat fields have been over threshold.

Cereal Leaf Beetle Larvae

There was a lot of frost damaged corn at the Cornell Research Farm in Valatie. There was also some seeding damping off of a small portion of the corn.

Frost Damaged Corn

Black cutworm flights in areas of Pennsylvania have increased this week.  In Michigan they report an increase in damage by black cutworm larvae.

Stay alert and look for damage. The early instars of this insect feed on the leaves and as they get larger you will start to see cut plants.

Table 1: Black Cutworm Degree Days

Degree Days Stage Feeding Activity
0 Moth Capture Egg Laying
90 Eggs Hatch
91-311 1st to 3rd Instar Leaf Feeding
312-364 4th Instar Cutting Begins
365-430 5th Instar Cutting Begins
431-640 6th Instar Cutting Slows
641-989 Pupa No feeding
Source: 2013 University of Minnesota Black Cutworm Trapping Network
We will use May 14 as our starting date for calculating the degree days using the NEWA Growing Degree Days website.

Table 2: Black Cutworm Degree Days for NY, May 14 – May 29, 2013

Base 50 F Stage of Development
Chazy 105 Egg
Geneva 168 1st to 3rd Instar-Leaf feeding
Highland 170 1st to 3rd Instar-Leaf feeding
Ithaca 160 1st to 3rd Instar-Leaf feeding
North Easton 149 1st to 3rd Instar-Leaf feeding
Versailles 174 1st to 3rd Instar-Leaf feeding
Watertown 123 1st to 3rd Instar-Leaf feeding

This first PLH of the season detection goes to Eric Nixon (WNYCMA). PLH are being found in very low numbers in western NY alfalfa. Keith Waldron found a few at the Cornell Research Farm in Geneva this week as well. WNYCMA consultants are also reporting low numbers of common armyworm being found in a few grass : alfalfa mixture and corn fields in western NY counties. It is not uncommon to find some armyworm larvae in NY every season. The question is how many and where? It is always recommended to look for this insect and other early season pests of while scouting corn and other grass crops. There is no indication to suspect a repeat of last years widespread damaging armyworm activity.  That said.. It’s always a good idea to be proactive and walk your fields and check!

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Weather Update

May 30, 2013
Jessica Rennells, NOAA Northeast Climate Center, Cornell University

Last week temperatures ranged from 3 to 6 degrees below normal for most of the state.  Precipitation ranged widely from 1 inch up to 4 inches.  The base 50 growing degree-days ranged from 25 to 50.

Hot weather & storms before returning to seasonal temperatures.

Possible severe storms on Sunday.

Today (Thursday) will be mostly sunny and hot!  Temperatures will be in the mid 80’s to near 90 with a slight chance for afternoon showers or thunderstorms.  Overnight temperatures will range throughout the 60’s.  Friday will be mostly sunny and hot again; temperatures will rise into the upper 80’s and low 90’s with a chance for thunderstorms.  Overnight temperatures will range throughout the 60’s.    Saturday will be partly sunny with highs in the mid 80’s to near 90.  Light rain and thunderstorms are possible in the afternoon.  Lows will be in the low to mid 60’s. Sunday will be mostly cloudy with highs cooler but still above normal, in the mid 70’s to low 80’s.  Showers and thunderstorms are likely as a front passes, some possibly severe.  Overnight lows will be in the mid 50’s to low 60’s.  Monday will be cloudy and notably cooler, but seasonable, because of the frontal passage.  Highs will be in the upper 60’s to mid 70’s with light rain possible.  Monday night will be in the upper 40’s to mid 50’s. Tuesday will be mostly sunny with highs in the upper 60’s to low 70’s.  Lows will be In the upper 40’s to mid 50’s. Wednesday will be in the upper 60’s to low 70’s.  Lows will be in the mid 40’s to near 50.

The five-day precipitation amounts will range from ½” to 1 ½” . The 8-14 day out look (June 6 – June 12) is showing above normal temperatures and above normal precipitation.  Abnormally dry area reduced, still includes areas of Catskills, low Hudson Valley Region, Hamilton and Herkimer counties.

Maps of 8-14 day outlooks

National Weather Service watch/warning map

NRCC Drought Page which features the US Drought Monitor map

(updated every Thursday)

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Quantifying Row Crop Plant Populations

Keith Waldron, NYS IPM

Plants missing from within your crop rows?
It’s important to evaluate stands early to determine if the optimal plant population has been achieved. A good stand or a replant situation? One EZ method for determining plant populations is to count the number of plants per 1 / 1,000th of an acre. Determine the length of row you’ll need to count plants in by referring to the row width table below. Then determine the average of at least three sets of emerged plant counts found at several locations throughout the field to get the average number of plants per acre. Finally, determine the average number of plants found in the length of row sampled and multiply by 1,000 to get the average plant population.

Locate wheel tracks and make observations for each row planted. Check at least three areas within the field for consistency and to determine if all planter boxes were operating well.

Row Width (in)
Length of Row per 1/1,000 of an acre
Feet Inches
7 74 8
15 34 10
28 18 8
30 17 5
32 16 4
36 14 6

 A 10% reduction in number of plants observed vs number of seeds dropped is not uncommon. Large deviations from what was expected can signal a variety of potential problems. If your plant population counts are not up to snuff, sometimes waiting a few days and re-doing the estimate can make a difference if there is uneven germination from cool temps or variations in seeding depth. Other potential problems can be related to poor seed germination, planter calibration, performance and planting associated problems, poor soil conditions such as cold soil temperatures, crusting, poor seed soil contact and excess moisture, seed rots or seedling diseases, seed corn maggot, wireworm, white grubs, birds, mice, and other factors.

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Fusarium head blight update, May 31, 2013:

Gary Bergstrom, Extension Plant Pathologist, Cornell University

Heads have emerged and flowering has begun or will soon begin for most of the winter wheat and winter barley crops in New York State. This is a critical time for assessment of disease risk and for making a decision to apply an effective triazole fungicide, i.e., Caramba, Prosaro, or Proline, for suppression of Fusarium head blight (FHB), reducing the risk of deoxynivalenol (DON) contamination of grain, and protection of flag leaves from foliar diseases. The Fusarium Risk Assessment Tool currently projects a low risk of FHB infection, but this could change as warm, humid conditions with scattered showers are forecast through this weekend.  The extended forecast through the early grain-filling period calls for above-normal temperatures and precipitation that could favor development of fungal foliar diseases that are currently at low levels. There is an application window of approximately 5-6 days from the beginning of flowering (Feekes 10.5 in barley and Feekes 10.5.1 in wheat) in which reasonable FHB suppression can be expected.

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Spring Related  Alfalfa Diseases

Ken Wise, NYS IPM

Spring Black Stem: is favored by cool and moist weather in early spring. Symptoms appear as irregularly shaped brown to black spots that can merge to form a larger blotch. This disease can infect the petiole, form elongated blackened areas on the stems, and may be a contributor to a crown rot. Spring Black Stem

Common Leaf Spot: proliferates when the weather is cool and wet. This disease first develops on the lower leaves near the soil surface and then progresses upward through the canopy. Common leaf spot appears as small, circular, dark brown to black spots, about 1/16 inch in diameter. When observed through a hand lens, tiny raised, light brown disk-shaped fungal fruiting bodies are visible in the center of mature lesions. See photo at: Common Leaf Spot

Leptosphaerulina Leaf Spot (aka “Lepto”): is also favored by cool and moist weather in early spring and late summer to early fall. The lesions usually start as small black spots and enlarge to oval or round “eyespots” 1/16 to 1/8 inch across. As lesions develop they become light brown or tan with dark brown borders; often surrounded by a chlorotic (yellow) area. This disease primarily attacks young leaflets but may also attack petioles and other plant parts. See photo at: Leptosphaerulina Leaf Spot

Downy Mildew: causes leaves to become blotched or chlorotic (light green or yellow). Many times young leaflets can become distorted. Often a dark purplish-gray fungal mat covers the underside of the leaves. This disease is common early in the spring. See photo: Downy Mildew

While alfalfa leaf spots may be easily found in most stands the real impacts for this harvest would be if 30% or more of the leaves on plants were shed as the result of infection.

For more information view our on-line management guide: Diseases of Alfalfa Leaf Spots Management Guide

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Alfalfa Weevil Growing Degree Days

Ken Wise, NYS IPM

Table 3: Growing degree Days for peak (50%) Occurrence of Alfalfa Weevil growth stage:

Stage or Event Accumulated growing degree days (48F base temperature)
Eggs hatch


Instar 1


Instar 2


Instar 3


Instar 4






Adult Emergence



Table 4: Current Growing Degree Days in NYS, March 1 – May 28, 2013

Location Base 48°F Base 50°F
Chazy 358 297
Geneva 428 357
Highland 461 337
Ithaca 411 292
Versailles 481 404
Watertown 355 288
NEWA Growing Degree Days
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Clipboard Checklist

Keith Waldron, NYS IPM


*Walk fields to check general field condition, weed issues, areas of soil erosion
*Watch for early season annual and perennial weeds

*Evaluate established legume stands for approximate days til harvest
*Monitor for alfalfa weevil, potato leafhopper
*Monitor new seedings for Pythium blight and Phytopthora Rot Rot.
*Monitor for Alfalfa Snout Beetle (In Oswego, Jefferson, Cayuga, Wayne, Lewis, St. Lawrence, Clinton, Essex, and Franklin counties)

Small Grains:
*Monitor winter grain fields for growth stage, disease issues, cereal leaf beetle
*Check stands for soilborne virus diseases, Wheat spindle streak mosaic and Soilborne wheat mosaic and powdery mildew symptoms, cereal leaf beetle, weed escapes, goose damage

Pre-plant weed evaluation, timing cultivation and/or pre-plant weed management
Conduct plant population assessments, early season corn pests including seed corn maggot, white grub, wireworm, cutworm, armyworm, slugs, diseases, weed issues, vertebrate damage

*Prepare land and plant soybeans as soon as conditions allow
*Pre-plant and/or post emergence weed evaluation, timely cultivation and/or weed management
*Conduct plant population assessments, early season corn pests including seed corn maggot, slugs, diseases, weed issues, vertebrate damage

Check and mend fences as needed.
*Check crop growth
*Invasive species, plants harmful to livestock
*Review/Plan rotation system

*Remove / clean soil and crop debris from equipment
Arrange for custom weed control or check your own application or cultivator equipment for repairs.
*Carry appropriate / necessary NYS DEC and EPA required documents: (pesticide applicators license, pesticide labels, MSDS sheets, etc.) with application equipment

  • planting equipment – maintain records on planting rate per field
  • manure spreaders – maintain records on amount spread per field
  • pesticide application equipment – Check nozzles, pumps, etc., recalibrate pesticide application equipment before use. Maintain pesticide use records

* Check stored grain bins for temperature, moisture and signs of mold and insects. Aerate, core, transfer grain or treat as necessary
Check forage allocation and anticipate feed program adjustments as forages from previous year are used up
*Plan where forages should be stored for optimum allocation next feeding season
*Mow around storage bins and facility to minimize pest hiding places

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