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Weekly Field Crops Pest Report 2006

May 26, 2006 Volume 5 Number 6

1. View from the Field

2. Alfalfa Weevil Biological Control

3. Barn Fly Management-Breeding Hot Spots Where to Watch and What to Do!

4. Will Conditions Be Favorable for Fusarium Head Blight (Scab) This Year?

5. Keeping Pest Records

6. Growing Degree Days in NYS

7. Clipboard Checklist

8. Contact Information

View From The Field
Eastern NYS

Ken Wise, NYS IPM

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Julie Stavisky, NYS IPM









Keith Waldron, NYS IPM

Poplar Ridge Road, Aurora, NY
Thursday, June 8, 2006
Coffee at 9:30 AM
Program 10 AM to Noon

There seems to have been an increase in alfalfa weevil activity. In 4+ year old fields at the Cornell University Research Farm in Valatie tip feeding is 30 to 35%. Remember the action threshold for alfalfa weevil before the 1st cutting is 40% tip feeding. The larvae ranged for 1st to 3rd instar in development. Again remember that the 4th instar consumes 80% of all the forage it will ever eat. While feeding on alfalfa right now looks minimal, if the alfalfa weevil is allowed to reach the 4th instar they can cause economic losses if they are in large numbers.

Alfalfa Weevil Larvae Feeding on Alfalfa in the Bud

I found a few spittlebugs in my sweep net this week. Sometimes people confuse spittlebugs with potato leafhopper when scouting alfalfa fields. In reality they look a lot different. Potato leafhopper is lime green while spittlebug’s first instar can appear orange, instars two through four are yellow and the last is pale green. You can also find this larva in the middle of what looks like saliva on the plant. This is where the larvae lives until it becomes an adult. The adults are sometimes called frog hoppers. Spittlebugs rarely cause economic losses.

Meadow spittlebug

In the triticale plots at the Cornell University Research Farm in Valatie Stagonospora nodorum blotch appears to be moving up the plant a little bit. The disease still is in the lower part of the plant and is not a major pest issue at the moment. Most of the triticale has headed out and will flower soon.

At a TAg Team meeting last week in Seneca County, we observed a fair amount of alfalfa weevil (AW) larval feeding.  When the team walked through the field and conducted the sampling (50 stems chosen randomly from throughout the field), 10 of the stems showed the tattered, shot-hole appearance that indicates AW feeding. Since the economic threshold is 40% of stems showing injury, we were comfortably below threshold.  Additionally, the field was within 10 days of cutting.  For more information on AW, see our AW brochure online.

The cool, wet weather we’ve had since the end of last week is perfect for slugs.  I have not yet seen any major infestations in the corn fields that I’ve walked through.  Have you seen slugs yet in your locale?

Mike Stanyard and I have both searched on buckthorn plants for signs of soybean aphids that may have overwintered here in NY.  So far, we haven’t spotted any aphids.  We’ll keep watching.

Geneva area observations. Alfalfa harvest has begun for some farmers in the Finger Lakes area. Alfalfa at NYSAES farm 22 inches. Alfalfa weevil population has been low. Weevil larvae in the 1-3rd instars. Corn plantings generally look uniform, slightly yellow in color due to cool weather. Corn generally at VE to 2 leaf stage of development.  Higher temperatures predicted for later this week should improve crop color and stimulate growth. No soybean aphids observed on buckthorn.

Alfalfa Weevil Biological Control

Julie Stavisky, NYS IPM

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Recent statewide discussions have reminded us how vital biological control is to alfalfa weevil management.  Within 10 years of the arrival of the invasive alfalfa weevil in the US in the late 1940s, USDA scientists began releases of parasitic wasps to combat alfalfa weevil.  The parasitic wasp lays an egg in an alfalfa weevil larva, thus killing the larva of the pest insect and providing the food source for a growing parasitic wasp. We can generally count on these tiny wasps to help keep alfalfa weevil populations in check.  But how do we know if they are present in fields? One of the easier times to look for alfalfa weevil parasitoids is when they are in the pupal stage.  While searching for alfalfa weevil pupae on the ground below the alfalfa canopy later this month, keep your eyes out for the parasitoid pupae, too.  The alfalfa weevil pupa is surrounded in a white to tan webbing, and a wasp pupa is instead surrounded by a hard brown pupal case (see photos).  Enclosed in the brown case is the wasp pupa, which has grown up using the alfalfa weevil larva as its food source.

Alfalfa weevil pupae (Photo from Univ. of Nebraska)
Pupae of parasitic wasps of Alfalfa Weevil (photo from Univ. of Illinois)

For alfalfa weevil scouting guidelines, see our online publication: Alfalfa Weevil Management Guide

Barn Fly Management – Fly breeding hot spots – where to watch, what to do.

Keith Waldron, NYS IPM

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Each female house fly can lay between 100 and 150 eggs in each of the 4 - 6 batches of eggs produced over her 3+ week lifetime. Development from egg to adult can take as few as 9 - 11 days at a constant temperature of 86 F. At 68 F, the House fly life cycle may take as long as 18-21 days to complete. This is one reason why fly problems seem to explode almost overnight during the warmer summer months. Potential for population growth? One study showed that 25,000 to 40,000 stable and house flies could develop from bedding of a single calf hutch during the summer. Under favorable environmental conditions it is easy to see how fly populations can explode in a very short amount of time.

Shutting down fly production begins with cultural practices that eliminate conditions favorable to fly breeding. House flies and stable flies both breed in areas where moist undisturbed organic matter such as spilled feed, moist hay, wet grain, and manure-soiled bedding are present. Another favorable breeding spot is a location that remains relatively undisturbed and offers protection from traffic – foot and hoof traffic that is.

Location, location, location. Flies seek out habitat that favors their survival. The most likely places to search for barn fly breeding? Think moist, not wet, organic matter. These conditions favor the microorganisms that fly larvae feed on. Too wet or too dry are not favorable. Conditions have to be just right… High fly potential? Calf rearing areas, near waterers and feed troughs / bunks, adult animal resting areas, maternity and hospital pens, manure traps / conveyor systems. Outside areas adjacent to barns prone to fly breeding include the water and feed troughs in the animal loafing yard, base of stored big bales, and edges of bunk or standing silos. See diagram below. Areas less conducive to fly breeding? Dry areas such as dry feed troughs bedded packs, well managed manure storage or transfer areas. Stanchion barns are more likely to have more fly issues than free stall barns. One reason is the relative number of hard to clean corners and other areas where organic matter can accumulate, another is amount of ventilation to dry out what would otherwise be moist conditions. Areas with standing water are not typically good habitats for house and stable flies except perhaps at the edges if organic matter is present. These wet areas may attract other fly species including fungus gnats, rat tail maggots and mosquitoes.

1 = calf hutches, calf holding areas; 2 = silo leak and spill area; 3 = animal stalls, pens, feed prep areas, mangers, water sources; 4 = calf, hospital, maternity areas; 5 = water tanks; 6 = feed troughs; 7 = manure handling areas.

Cultural Control – the first line of defense. Cleaning areas where fly breeding is known or suspected to occur is critical for minimizing on-farm generation of fly populations. Check and clean areas known to accumulate organic matter and are prone to moisture. Sanitation very effectively stops flies from completing their life cycle by removing food sources and physically removing any developing larvae before they have had the chance to pupate. Fly development time is important to consider for frequency of animal holding area cleaning up. Weekly cleanup is recommended at the minimum, with more frequent cleanup is recommended during warmer months. If labor or time is tight for cleaning, concentrate on animal holding areas, especially those housing calves, first. Think Dry! Check corners and hard to clean areas in and around animal pens / stalls. Check for sources of moisture such as leaky water sources and hoses, problems with or lack of roof gutters, poor barnyard drainage, etc. When changing calf water buckets, empty old water buckets outside, away from animal bedding and feed.

Adult flies can be removed from the breeding pool using sticky traps and baits. In barns and settings where flies are present, and wind and dust challenges are minimal consider using sticky tapes, ribbon or paper to trap flies. Install the sticky device out of reach of animals, children, and your hat. If using the large sticky paper rolls (14 in by 24 ft) roll out a 8-10 ft portion at a time, rolling up the used section and exposing fresh material as the original section collects flies or as the paper becomes less sticky. Fly traps using a methomyl insecticide / sugar bait such as Blue Streak or Golden Malrin in a gallon plastic jug modified with several 1 inch in diameter holes on the top are another very effective way to reduce adult fly numbers. Hang bait jugs using stiff wire in areas where flies tend to be found, out of reach of animals and out of the way of barn activities. Follow label instructions being careful not to over apply – too much of the bait will actually repel flies.

Monitoring and Thresholds. Two methods are recommended to monitor house and stable flies in the barn: spot cards and direct observation. The spot card method takes advantage of the natural tendency for flies to rest and leave (regurgitation and fecal droppings) spots they have visited. Spot cards can be mounted to posts, beams, walls, etc. Select areas 10 areas throughout the barn where flies are seen resting. Do not put cards in windy areas. Draw a map to indicate card location and save as part of your fly management record.  Date and number the cards and change them weekly. After 1 week remove the cards and replace them with a fresh set. Count the number of spots found on each index card. One hundred (100) spots per card can be used as a guide to indicate a fly problem. Each farm can adjust this number to their individual tolerance threshold. The cards provide an objective means to monitor relative fly activity over time. Spot cards can be very helpful for communicating fly population changes over time with on-farm personnel and should the need arise… curious or concerned neighbors. Check areas surrounding spot cards with high counts for fly breeding. To monitor specifically for stable flies (the biting flies) check the legs and bellies of 10 animals and count number of resting flies. Check calf legs for patches of thin hair which can indicate a reaction to stable fly feeding. Ten stable flies per animal are considered a high number. Keep records of spot card and stable fly counts for reference.

More information can be found in the Cornell IPM Factsheet: Integrated Management of Flies in and around Dairy and Livestock Barns

Next week Biological Control Do’s and Don’ts.

Pdfs of the dairy cattle recommendations, factsheets and more can be found at: Veterinary Entomology

Will Conditions be Favorable for Fusarium Head Blight (Scab) This Year?

Julie Stavisky, NYS IPM

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One of the most devastating diseases of wheat is Fusarium head blight, or scab.  The disease reduces yield by decreasing the number of viable kernels, but the more significant impact is that the fungus in diseased kernels may produce a mycotoxin.

Scab is caused by airborne spores of the fungus Fusarium graminearum that dwell in nearby crop debris, including corn stalks and wheat straw. This is the same fungus that can cause root, stalk, and ear rots of corn.  Since the fungus is very widespread, likelihood of exposure is generally not reduced by crop rotation or other cultural practices.  Extended periods of warm, moist weather at crop flowering can cause the anthers to be infected just after their emergence, killing the florets and preventing kernels from developing.  Symptoms of scab become visible on emerged heads soon after flowering.  During early grain fill, the disease shows up as pink to salmon orange on infected kernels.  As kernel fill progresses, the infected kernels appear bleached. Spikes that are infected later than flowering will produce diseased kernels that are shriveled in appearance.

Next week, watch for information regarding fungicides for Fusarium head blight suppression and a scab Risk Assessment Tool.

Keeping Pest Records

Ken Wise NYS IPM

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It is very important to keep records from year to year on what major pest problems may have occurred. Write down observations that you make over the course of this summer while they are fresh in your mind.... Did potato leafhoppers infestations go over threshold. Were there corn diseases a problem? Which diseases? Did you have corn rootworm injury? Were there new weeds or weed escapes you did not expect this year? Pick up a pencil and write them down on a field to field basis to better select certain management practices the next season. For example, if you were hit with potato leafhoppers this season and you want to rotate your alfalfa, one management option is to use potato leafhopper resistant alfalfa. Another example might be to select wheat varieties that are resistant to certain diseases based on field observations that you wrote down last fall. If you have weed escapes you might reconsider your selection of weed control products. If you wait too long you may forget what happened in certain fields. So write them down, NOW!

Alfalfa Weevil and Growing Degree Days in NYS

Ken Wise NYS IPM

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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


(Note: for alfalfa weevil predictions use Base Temp of 48F)

Accumulated Growing Degree Days for March 1 to May 24


Base 48 F

Base 50 F







Clifton Park


















*indicates missing data

Do you know the number of growing degree-days in your region today? Check this website: NY Growing Degree-Day Tracker Base Temp. 50F.

Clipboard Checklist

Keith Waldron-NYS IPM

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* Maintain crop records by field, including variety, planting date, pesticides used, nutrient inputs including manure, etc.

* Watch for early season weeds, any patches of herbicide resistant weeds?

• Storage areas cleaned and ready to accept upcoming hay harvest?


• Determine plant populations, make notes on germination problems

• Gaps in row? Check for seed corn maggot, wireworm, seedling blights, birds, seed placement issues?

• Monitor for weeds, note presence of “who”, “how many” and “where”

• Adjust post emergence weed control actions

Small Grains:

• Monitor winter grains for crop stage, insect and disease problems

      - assess crop for adequate stand and plant vigor

Alfalfa & Hay:

• Monitor alfalfa seedings for weeds, insects & diseases.

• Check established alfalfa stands for alfalfa weevil, weed and disease problems.

• Storage areas cleaned and ready to accept upcoming harvest?


• Check stand establishment of early plantings

• Gaps in row? Check for seed corn maggot, wireworm, seedling blights, birds, seed placement issues?

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 waterers, drainage, roof gutters for leaks and potential overspill

• Begin fly monitoring: install “3X5” index card fly speck monitoring cards through out barn

• Order fly management materials: fly tapes, insecticide baits, natural enemies (parasitoids)


• Note any repairs needed for recently used equipment.

• Soybean planter and alfalfa harvesting equipment ready?

• Calibrate manure spreaders - maintain records on amount spread per field

Contact Information

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Julie Stavisky: IPM Area Educator, Livestock and Field Crops, Western NY
Phone: (315) 331-8415
Fax: (315) 331-8411
Email: js38@cornell.edu

Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Phone: (315) 787 - 2432
Fax: (315) 787-2360
Email: jkw5@cornell.edu

Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock
Phone: (518) 434-1690
Fax: (518) 426-3316
Email: klw24@cornell.edu