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Weekly Field Crops Pest Report 2012

July 20, 2012, Volume 11 Number 14

  1. View from the Field
  2. Weather Outlook
  3. True Armyworm - Second generation found in western and northern New York
  4. Western Bean Cutworm Update
  5. Clipboard Checklist
  6. Contact Information

View from the Field

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Another wild week in NY for field crops pests. Potato leafhopper (PLH) has been reported over thresholds statewide. Hundreds of alfalfa fields have been damaged. The PLH nymphs do most of the damage. I was in a field at the Cornell Research farm on Monday of this week, In my10 samples (each sample is 10 swings of the net), I roughly counted 1,300 PLHs. Almost all of them were nymphs.

True armyworms seem to be surging back in some locations in NY. Remember that huge explosion we had earlier in the growing season. These are the second generation of those initial infestations. They have been found at high levels in some areas in Northern NY. Elson Shields recommends that “small worms are best to control and the easiest to kill before they get large and start consuming a lot of forage. In addition, the dry weather and shortage of forage make the control decision easier to make. Thresholds are not very available for these situations, but I would guess that situations where there are more than 2-3 armyworms per sweep would be a spray situation.” Scout for armyworms late in the day since they are mostly nocturnal feeders. For more information on the second generation of armyworm, see the article following the weather report.
Jeff Miller reports finding stem rust on oats. Stem rust can be very destructive in small grains. There are several races of stem rust. The race on oats only attacks oats, wild oats and meadow fescue.

Dave Balbian and I did 4 pasture- and barn-fly field meetings this week. We looked at a lot of cattle. This year, face fly seems to be at very high levels in all pastures. It some cases there were 70 or 80 flies on cows’ faces. The threshold is 10 flies per face.

face flies

Face flies (40 face flies—not including what was on the nose)

Weather Outlook

July 19, 2012
Jessica Rennells, Northeast Region Climate Center, Cornell University

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Last week, temperatures ranged from 3 to 9 degrees above normal. Rainfall amounts ranged from a trace to an inch for most of the state, with some areas having over an inch. The Base 50 growing degree-days ranged from 125-200 for most of the state.

Friday is mostly sunny in the mid 70s to low 80s with a chance for showers from a passing low-pressure area. These showers, and possibly a thunderstorm, will be confined to the southern areas of the state. Overnight temperatures will be in the mid 50s to low 60s. Saturday will be mostly sunny with highs in the low to mid 80s as high pressure dominates and brings fair, dry conditions with lows in the low to mid 60s. Sunday will be mostly sunny, but with a slight chance of scattered showers and thunderstorms. Highs will be in the mid to upper 80s and lows in the low to mid 60s. Monday’s temperatures will be in the 80s with a chance for showers and thunderstorms; lows in the 60s. On Tuesday, highs will range from the upper 70s to mid 80s with possible showers and thunderstorms from a quick-moving cold front. Overnight lows will be in the mid to upper 60s. Wednesday’s temperatures will be in the mid to upper 80s with lows ranging from the upper 50s to mid 60s.

The five-day precipitation amounts will range from a tenth to an inch, with the higher amounts in the southern areas. The 8-14 day outlook shows normal temperatures and precipitations. Abnormally dry conditions cover almost all of the state. Moderate drought has been expanded to most of the Great Lakes and Central Lakes regions and into the Mohawk Valley and Eastern Plateau.

National Weather Service Climate Prediction Service Maps of 8-14 day outlooks

National Weather Service Eastern Region Headquarters watch/warnings map

NRCC Drought Page which features the US Drought Monitor map (updated every Thursday)

True Armyworm - Second generation found in western and northern New York

Keith Waldron

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Note: The second generation of armyworm has generally not caused significant economic problems in NY. Given the extent of armyworm activity earlier this season, however, it would be prudent to monitor grass and corn fields closely for this pest in the next few weeks…

Reports of true armyworm larvae in grass hayfields came in this week from the North Country (Jefferson, Lewis, and Washington counties). Larvae were small, from under 1/8 to ½ inch long—small enough that they are difficult to find by searching through grass by looking into the canopy and down to the ground surface.

You’ll get better results this early in the game by sweeping with a standard 15” diameter sweep net. True armyworm are nocturnal, so sampling for them in the evening is best; early morning or very late afternoon provide higher captures than if you sample in the heat of the day. This technique is, however, a departure from the usual method to determine the average number of larvae per unit area or per plant and associated management action guidelines (see below). Cornell’s field crop entomologist, Elson Shields, suggests 2-3 armyworm larvae per sweep could indicate a field at risk. 

2nd generation early instar true armyworm

Young true armyworm larvae collected July18, '12 from grass hayfield in Jefferson County NY

One consideration when making management decisions is to look for natural enemies: Tachinid fly parasites (which lay their eggs behind the armyworm larva's head.) and fungal and viral diseases. During the first-generation infestation, few tachinid flies were reported, though diseased armyworm larvae were found in western NY. Diseased larvae climb to the upper regions of plants before they die. These larvae can look fuzzy (the fungal disease) or dark and shriveled, almost appearing to melt (the virus disease). Under the right conditions, these natural enemies are quite effective in reducing larval numbers. See: True Armyworm (aka Common armyworm) Alert

Sampling for armyworm:

Check grass hayfields and cornfields for armyworm larvae and signs of feeding. Also monitor edges of fields adjacent to grass hay, grassy ditchbanks, fields with poor grass weed-control, etc. If you find larvae, scout 5 or more areas within field interior. Consider border spray treatments if warranted.

Action threshold guidelines:

Grass pastures - Midwestern extension guidelines suggest i nsecticides are justified when four or more nonparasitized, half-grown or larger larvae are present per square foot. No specific guidelines are available in NY. The need for treatment should be based on the level of damage observed in relation to the expected value of grass harvest. REMEMBER… if you have a true armyworm infestation in a mixed alfalfa–grass stand, alfalfa and grass BOTH NEED to be on the insecticide LABEL to be a legal application. If treatment is necessary, be sure that the insecticide is labeled for true armyworm and the crop. Be careful to consider the pre-harvest interval when making decisions. Spray coverage is very important. Use higher spray volume for better coverage. Read and follow label instructions.

If field monitoring determines armyworm numbers have reached control guidelines, consider treating only the infested portion of the field and a 20- to 40-foot border around it. A border 20 to 40 feet wide treated with insecticide will prevent armyworms from invading from an adjacent infested field. Because larvae are active at night, apply treatments late in the day.

Corn – Penn State extension specialists recommend treating seedling corn when 10 percent or more of seedlings are damaged and larvae are still present. For whorl-stage corn, apply an insecticide only if most plants show damage and you find about three larvae per plant. Tall corn will seldom need treatment unless the leaves above the ear are also damaged. Note: control can be challenging if caterpillars are greater than one-inch long.

Western Bean Cutworm Update

Keith Waldron

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Western bean cutworm (WBC) Update
Sixty-six western bean cutworm pheromone traps are providing data to the Cornell WBC monitoring effort which began during the week of June 10. That week 2 WBC moths were caught in Chautauqua County. By contrast, the first WBC captures last year occurred the week of June 28. Statewide, WBC traps yielded 0 – 51 moths per trap this week. Sixteen locations have not caught any WBC moths thus far. Unusually high numbers were caught this week in Lewis, St. Lawrence, and Jefferson counties: 51, 46, and 41 respectively. The St. Lawrence trap has caught 102 moths over the last 3 weeks. The large number and the condition of the moths in these traps suggests these moths travelled some distance and were migrants, most likely from Ontario. (Moths recently captured in NY have typically been in relatively good condition, indicating local sources). Excluding data from the 3 North Country traps, this week’s statewide average has been 6 WBC per trap with an average total accumulated catch per trap of 9 moths.

Our current average trap numbers generally do not indicate significant concern. Total accumulated trap catches approaching 100 WBCs per trap would warrant monitoring adjacent cornfields for presence of egg masses. Western bean cutworm females are most attracted to late whorl/pre-tassel stage corn. They lay masses of 50-200 eggs on the top surface of a leaf near the tassel. Eggs are cantaloupe shaped – white when first laid, turning purple before hatching. See the factsheets listed below for photos.

Monitoring in field and sweet corn: search tassel-emergence and silk stage fields for western bean cutworm eggs and larvae. The threshold for WBC used in Michigan and Ontario is 5% of plants with egg masses. As with other boring insects such as ECB, it's important to control western bean cutworm before it enters the ear and is protected from an insecticide application. Focus scouting on fields that have plants with at least a tassel developing in the whorl of the plant as well as those with the tassel fully emerged but not fully shedding yet. These fields seem most attractive for the moths. If fields have variable plant heights, you’ll likely find a higher concentration of eggs on shorter corn.

WBC scouting in dry beans can be hard. Egg masses are laid on the underside of leaves and larvae difficult to find, since they feed at night and hide in the soil during the day. Ontario and Michigan researchers have found that you should expect pod feeding 10-20 days after peak moth flight. If you don't have WBC traps in your own fields, get an idea of when traps in your area have reached peak moth flight.

western bean cutworm egg mass close up
Close up of Western Bean Cutworm egg mass, note striated pattern on eggs.


western bean cutworm egg mass

Western Bean Cutworm egg mass in whorl close to un-emerged corn tassel 

WBC Factsheets:
from the University of Illinois
from the University of Wisconsin

WBC monitoring information is available at:
Cornell Sweet Corn Monitoring Network
Penn State Pest Watch (Includes WBC data from NY, New England and other states)
Ontario WBC Trap Network

Western Bean Cutworm - Corn scouting videos:

Clipboard Checklist

Keith Waldron

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* Emergency contact information ("911", local hospital, Chem. Spill emergency contact, other?) posted in central posting area
* Maintain crop records by field, including variety, planting date, pesticides used, nutrient inputs including manure, etc.
* Watch for any patches of herbicide resistant weeds, weed escapes
* Storage areas cleaned and ready to accept hay, wheat harvest
* Monitor fields for plant vigor, growth stage, vegetative stage pest issues (corn rootworm larvae, European corn borer, armyworm, foliar diseases, nutritional deficiencies)
* Monitor for weeds, note presence of "who", "how many" and "where"
Small Grains:
* Evaluate crop for maturity, lodging, time till harvest
* Grain bins ready to accept upcoming harvest?
Alfalfa & Hay:
* Monitor alfalfa seedings for weeds, insects & diseases.
* Check re-growth of established alfalfa stands for potato leafhopper, weed and disease problems.
* Storage areas cleaned and ready to accept incoming harvest
* Monitor grass hay fields for armyworm
* Evaluate stand growth, development and condition
* Monitor fields for soybean aphid, foliar diseases, white mold, natural enemies, weed escapes, spider mites
Dairy Livestock Barn Fly Management:
* 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
* Check water sources, drainage, roof gutters for leaks and potential overspill
* Continue fly monitoring: install "3X5" index card fly speck monitoring cards through out barn
* Install/refresh/replenish as needed: fly tapes, insecticide baits, natural enemies (parasitoids
Dairy Livestock Pasture Fly Management:
* Monitor animals for presence of pasture fly pests. Treatment guidelines: Horn flies (50 per dairy animal side, 100 per side for beef cattle), face flies (10 per animal face), stable flies (10 per 4 legs). See: (
* Consider installing biting fly traps to reduce horse, deer and stable fly populations.
* Check storage areas (bunk silos, etc.) for readiness to accept upcoming wheat harvest
* Clean in and outside of storage bins and grain handling equipment
* Keep areas around storage bins and silos clean and mowed
* Check areas around storage bins and silos for vertebrate tunneling
* Check temperature of recently baled hay in hay mow

* Note any repairs needed for recently used equipment: tractors, tillage implements, planters, sprayers, etc. as they are cleaned and serviced.
* Service hay harvesting equipment as needed.
* Calibrate manure spreaders - maintain records on amount spread per field

Emergency responder information on pesticide spills and accidents…
CHEMTREC - 800-424-9300

For pesticide information
National Pesticide Information Center: 800-858-7378

To Report Oil and Hazardous Material Spills in New York State
NYS Department of Environmental Conservation Spill Response - 800-457-7362 (in NYS), 518-457-7362 (outside NYS)

Poison Control Centers
Poison Control Centers nationwide -  800-222-1222

If you are unable to reach a Poison Control Center or obtain the information your doctor needs, the office of the NYS Pesticide Coordinator at Cornell University, 607-255-1866, may be able to assist you in obtaining such information.

Contact Information

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Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Phone: (315) 787 - 2432
Fax: (315) 787-2360

Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock
Phone: (518) 434-1690
Fax: (518) 426-3316