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Weekly Field Crops Pest Report 2012

June 15, 2012, Volume 11 Number 9

  1. View from the Field
  2. Weather Outlook
  3. True Armyworm (aka Common armyworm) Alert
  4. Clipboard Checklist
  5. Mark Your Calendars
  6. Contact Information

View from the Field

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True Armyworm is hitting western NY hard. They have been over economic threshold in wheat, grass hay, alfalfa/grass mixes and corn. They’re in mixed sizes, meaning adult moths came in on several different weather fronts. Eggs were laid different days and possibly weeks this spring. This will extend the time armyworm will feed in fields. Once one generation pupates, there are still others behind it.

In the past we’ve seen good biological control of this pest. This year we are not seeing many, and some speculate the second generation will be at higher levels. Over 60 wasps and fly parasitoids infect armyworm, along with pathogens that help control a population when it gets very large. This has been seen in a few wheat fields in Western NY. The armyworm will crawl to the wheat head, dies, and shrivels up.

At times birds help control armyworms. Once the forage has been cut, birds flock in and eat the larvae. The problem is, like with the pathogen and parasitoids you never really know when they will occur.

Armyworm has also been found over threshold levels in fields in Northern, Central and Eastern NY also. While armyworm aren’t as widespread in northern, central and eastern NY as in western NY, you STILL need to get out and look to make sure, because they’re over threshold in some fields. Reminder: if you spray, Armyworm and the Crop have to be on the label.

true armyworm in hand

True armyworm larvae appear smooth, cylindrical, and pale green to brownish when they are still small. Mature larvae are smooth and marked with two orange, white-bordered strips on each side. True armyworm ranges in size from 1/8 inch to 1.5 inches long.

Mike Stanyard found an uncommon soybean insect pest this week: variegated cutworm. They were in patchy areas across the whole field. If you see leaf-feeding damage in soybeans, do not mistake them for armyworms. Armyworm rarely feeds on non-grass plants.

variegated cutworm

Photo Taken by Mike Stanyard

Variegated cutworm has a line of yellow or whitish-yellow spots the center of the back. The body is mottled and variable in color ranging from gray to brown. The head has a dark net-like pattern with dark stripes.

Mike Stanyard also reports potato leafhopper (PLH) was over threshold in alfalfa in a few fields in Western NY. Several others have reported that they have found PLH but have not seen them at threshold levels. PLH has been reported statewide and it’s time to scouting alfalfa fields for this pest.

I was at the Willsboro farm looking at organic winter wheat, spring wheat and spelt variety trials this week. Many of these were heritage varieties. The wheat had a very high infection of Stagonospora nodorum, Septoria tritici and powdery mildew. The S. nodorum and S. tritici was on 100 percent of flag leaves. In some cases the leaves were turning brown while the head was still green. Powdery mildew was not in every plot or variety. Loose smut was in the some of the plots too, and we found some leaf symptoms that looked liked yellow dwarf virus. We also saw a little cereal leaf beetle damage. But—no armyworm at the Willsboro farm.

Western Bean Cutworm (WBC) monitoring began this week with traps being installed statewide. There were no WBC moths caught this week.

Weather Outlook

June 14, 2012
Jessica Rennells, Northeast Region Climate Center, Cornell University

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Last week temperatures ranged from normal to 6 degrees above normal. The warmer areas were in the Great Lakes and St Lawrence Valley regions. Precipitation amounts ranged widely from just a trace to over an inch. The base 50 growing degree-days ranged from 75 to 125 for most of the state. High pressure will be in control for most of the next week bringing mostly dry and warm weather. Today will be sunny with temperatures in the mid to upper 70s. Tonight will be clear and range from the low 40s to mid 50s.Friday will be sunny with highs in the mid 70s to low 80s. Lows will range throughout the 50s.Saturday will have continued sunshine and temperatures in the upper 70s and low 80s. Overnight temperatures will be in the mid 50s to low 60s. Sunday will be mostly sunny with highs in the low to mid 80s. Lows will be in the upper 50s and low 60s. Monday highs will be in the low to mid 80’s. Lows will be in the upper 50s to mid 60s. Tuesday highs will be in the throughout the 80s. Lows will be in the 60s. Wednesday’s temperatures will be in the mid to upper 80s, nearing 90 for some areas. Lows will be in the 60s.

The five-day precipitation amounts will range from a trace to a quarter of an inch. The 8-14 day outlook is showing normal temperatures for most of the state, the Hudson Valley region and southern Eastern Plateau are in above normal temperatures. Above normal precipitation is expected for the whole state.

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 (aka Common armyworm) Alert

Keith Waldron

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True Armyworm (aka Common armyworm) Alert - Update
Reports of true armyworm continue to come in from across New York. The highest concentration of armyworm activity to date has been in western counties with reports of more scattered incidence in central, northern and eastern New York. While reports have been confirmed in many counties, not all fields have been over threshold so it is important to get out and check your fields.  Checking your fields early and often is critical to avoid economic damage or unnecessary spraying. 

Armyworm moths are long-range migrants that arrive on the spring storms from their southern overwintering locations. Armyworm moth migrations are somewhat sporadic, cyclic from year to year and difficult to predict. This year the early spring in their overwintering areas enabled the moths to get an earlier start in their migrations north. True armyworms are primarily a pest of plants in the grass family: forage / pasture /grasses (& lawns), wheat, corn and small grains. Note: Under hunger stress true armyworms will also attack some legumes and other plants. Moths lay their eggs on weeds and/or grasses along field margins, on leaves of corn, or on small grains. Larvae hatch about a week later and develop over approximately a 3 week period, feeding mostly at night.

Fields at most risk for armyworms feeding are:

  1. grass or mostly grass hayfields, pastures. (Armyworms will also feed on grass lawns.)      
  2. wheat and other small grain fields and cut hay fields
  3. corn fields that:
    1. were planted into a small grain cover crop (such as rye grass)
    2. have grassy weeds, quackgrass, crabgrass and bluegrass and other perennials
    3. were planted into burned down sods, have grass weed issues, no-till or reduced tillage fields, fields with crop residue
    4. fields near severely infested small grain and cut hay fields, and in no-tillage corn established in grain stubble or on grassy land.

In many years natural enemies including various fungal and viral diseases and parasites such as tachinid flies, play a role in helping to suppress armyworm populations. This year our armyworm natural enemies appear to be lagging behind. Some tachnid fly parasitism has been observed in the Finger Lakes and diseased armyworm larvae are beginning to be observed in an increasing number of fields in western NY.

Armyworms may have 2 and possibly 3 generations in New York. Each generation takes about 5 weeks to complete. In a “normal” year the later generation armyworm impacts are usually minimal and or isolated. However, the presence of varying sized armyworm larvae (1/2 inch and greater) indicate there have been multiple flights and we may see an extended period of armyworm activity.

Many armyworms first observed in western NY around Memorial Day, are now about 1.5 inches in length or greater and may be pupating soon if not already. If so, the next generation of armyworms could be expected to be observed about mid July. To be sure, all crops at risk such as grasses and corn should be continue to be monitored for signs of this insect.

True armyworm larvae appear smooth, cylindrical, pale green to brownish when they are still small. Mature larvae are smooth and marked with two orange, white-bordered strips on each side. Larvae range in size from 1/8 inch to 1 1/2 inches long.

Healthy armyworm larva. Photo by K. Waldron, NYS IPM
parasitized true armyworm
Parasitized armyworm with white tachinid fly eggs. Photo by K. Waldron, NYS IPM
diseased true armyworm
Diseased armyworm larvae on wheat heads. Photo by K. Waldron, NYS IPM

Watch your fields!
It is important to detect armyworm infestations areas early, while larvae are still small. Large larvae do most of the feeding, are capable of destroying whole stands of corn, grasses and small grains and are harder to control. Armyworm larvae feed at night so look for signs of feeding: chewed ragged leaves, cut stems, lodged plants, pellet-like frass on the ground. Larvae tend to hide during the daytime often hidden under the plant canopy and in / under surface residue. In corn check under the canopy and within the whorl.

Armyworms can move from field to field in large numbers very quickly. As small grains begin to dry down or harvested, grass hay fields are cut or grass weeds dry down, larvae can move quickly to alternate hosts like corn. For management decisions refer to the monitoring and management guidelines below. Note the size of larvae and their relative number when making management decisions. Larger larvae eat more and 80% of the feeding damage happens in the last 7 days of larval feeding before pupation. There are several natural enemies that can impact armyworm populations including diseases and parasites. If there are sufficient numbers of armyworm larvae and damage is present, an insecticide could be justified. Larger armyworm larvae, greater than 1 inch long, are much more tolerant of insecticides, reducing the effectiveness and economic viability of this option. Always read, understand and follow insecticide label recommendations. Be aware of pre-harvest intervals.

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

Wheat – 3 to 5 or more larvae square foot, larvae less than 1.25 inches and not parasitized. Watch for flag leaf reduction or clipped-off heads as these will lead to yield losses. A spray before soft dough to save the remaining 3 upper leaves is generally beneficial since these tissues are still important to grain filling.

Grass pastures - Midwestern extension guidelines indicate insecticide treatments are justified when four or more non-parasitized, half-grown or larger larvae are present per square foot. No specific guidelines are available in NY, need for treatment 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 evaluate 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, where possible, 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 the larvae are active at night, apply treatments late in the day.

Armyworm identification Factsheets:
Armyworm (Pseudaletia unipuncta Haworth), 228k pdf file

Armyworm Damage to Field Corn and Grass Hay and Pasture

Armyworm as a Pest of Field Corn, 97k pdf file

Armyworm Management.
See armyworm management guidelines in crop(s) of interest at the Cornell Cooperative Extension Crop IPM Guidelines website

Help and advice on armyworm management?
Contact your local County Cornell Cooperative Extension Office

To stay informed on field crop production and pest management issues see the Cornell University - Cornell Cooperative Extension Field Crop News Blog

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.
*Walk fields to check crop condition, growth, and emergence. Look for signs of vertebrate pests (birds, ground hogs, deer, etc.).
*Mow around farm buildings to minimize rodent and other pest habitat
*Begin grain bin and auger clean up and preparations for storage.

Alfalfa and Grass Hay:
*Monitor alfalfa for crop condition, watch re-growth for alfalfa weevil, potato leafhopper, and diseases.
*Evaluate alfalfa seedings for weeds, insects (potato leafhopper, armyworm) & diseases.

Small Grains:
*Monitor winter wheat for foliar & grain head diseases, Fusarium Head Blight incidence
*Monitor winter grain fields for crop growth stage, signs and symptoms of diseases, weed pressure, insects (armyworm, cereal leaf beetle)

Field Corn:
*Post emergence: Determine corn plant populations, monitor for emergence problems, weeds, noting presence of "who", "how many" and "where"
*Early season corn pests: seedling blights, seed corn maggot, white grub, wireworm, black cutworm, armyworm, slugs, birds
*Adjust post emergence weed control actions

*Post emergence: Determine plant populations, monitor for germination and emergence problems, monitor for weeds, noting presence of "who", "how many" and "where"
*Monitor for soybean aphid

*Check and mend fences as needed.
*Check crop growth
*Check for presence of undesirable plant species harmful to livestock.
*Review/Plan rotation system

*Arrange for custom weed / disease management or check your own application or cultivator equipment for readiness or need for repairs.
*Check nozzles, pumps, etc., recalibrate pesticide application equipment regularly before use.
*Calibrate manure spreaders - maintain records on amount spread per field

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, 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 loafing yard
*Check paddocks for forage quality / quantity, rotate as appropriate
*Check paddocks for vegetation poisonous to livestock
*Consider use of fly traps to help reduce deer, horse and stable fly populations

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

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.

Mark Your Calendars

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Tuesday, 3 July 2012
For Seed Growers, Seed Treatment Applicators, and other Seed Professionals
Place: NYSIP Foundation Seed Barn, 791 Dryden Rd., Rt. 366, Ithaca, NY
Time: 8:30 AM-12:00 noon (registration starts at 8:30 and the program runs fro 9:00 until noon)

Freeville, NY (10 miles Northeast of Ithaca, Fall Creek Road, Rt. 366 extension)
8:00 a.m. Registration
Coffee (beverage), doughnuts, and informational trial packet
8:30 a.m.-11:30 a.m. Vegetable Crop Weed Control (Bellinder)

Aurora, NY (Poplar Ridge Road, connects 90 and 34B)
12:00 – 1:30 p.m. NYSABA Pork BBQ lunch at Musgrave Research Farm.
1:30 p.m. Registration
2:00 - 5:00 p.m. Field Crop Weed Control (Hahn)

CCA and DEC Credits have been requested for field crop and vegetable

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