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Weekly Field Crops Pest Report 2007

May 16, 2007                Volume 6 Number 5

1. View from the Field

2. Cereal Leaf Beetle is Having Winter Wheat for Breakfast!

3. How Do You Monitor Alfalfa Weevil?

4. Practice Soybean IPM Before Planting

5. Barn Fly Management – Not too early to start…

6. Growing Degree Days for NYS

7. Clipboard Checklist

8. Contact Information

View from the Field

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Eastern NYS-Ken Wise

Have you ever see a mummy in an alfalfa field? If you know what you are looking for you might also see a mummy. While up in Essex county for a soil health and an organic wheat pest management meeting we discovered a mummy….. an “aphid mummy” that is…

The common aphid found in our alfalfa fields is the pea aphid (Acyrthosiphon pisum). An aphid mummy is an aphid that had been parasitized by a small Braconid wasp (Aphidiius ervi). The parasitoid lays its egg inside the aphid and once it develops into a larva, it feeds on the inside of the aphid, thus, killing it.

While in alfalfa fields this week I found very few alfalfa weevil larvae and less than 5% tip feeding. As the weather gets warmer we can expect to see more alfalfa weevil in the fields. With the coming storms we might start to see potato leafhopper soon. Keep an eye out and a sweep-net moving!

Cereal Leaf Beetle is Having Winter Wheat for Breakfast!

Julie Dennis,

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It’s time to be scouting for cereal leaf beetles (CLB) in winter wheat. Adults of the cereal leaf beetle are 3/16 of an inch long, and their wing covers are a metallic bluish black color, while their legs and front sections are reddish. Eggs are laid on upper leaf surfaces near the midrib. Eggs are elongate, 1/16 of an inch long, and yellow-brown. They are laid singly or end to end in short chains of 2 or 3 eggs. Larvae are about 1/4 inch long, rounded, and usually covered with a slimy black coating.  Only one generation develops per year.

Because the flag leaf is so important for grain development and head filling, CLB larvae will be especially damaging if they feed on the flag leaf. Larvae feed on leaf surfaces between leaf veins, giving the leaves a striped appearance. Heavy infestations give the crop a yellowish white or frosted appearance, but plants can sustain considerable damage before you see any economic losses. And timing is everything - serious feeding damage in the late head-filling stage does not typically cause economic losses. 

Regular CLB monitoring, or scouting, should begin now and continue through early heading stages. Careful field monitoring for numbers of larvae present is the only reliable way to determine if insecticide application will be cost-effective. To scout a field, carefully inspect 30 stems throughout a field for the presence of eggs and larvae. The economic threshold is three or more eggs and larvae per stem before the boot stage, or one larva per flag leaf after the boot stage. If mostly eggs are observed, come back and scout again in about 5 days. Combine your monitoring with a general field walk-through in which you keep watch for weed hot spots and wheat diseases.

Use of insecticides for CLB is generally not warranted in wheat in New York State because natural enemies, including beneficial parasitic wasps as well as predators (such as lady beetles) generally keep populations in check. It is important to remember that if insecticides are sprayed unnecessarily or excessively, our allies, the natural enemies, will be killed before they can do their job.

Overall, when sound agronomic practices are used to ensure a healthy crop, impact from cereal leaf beetle will be minimized.


Cereal Leaf Beetle Adult

Cereal Leaf Beetle Larva

How Do You Monitor Alfalfa Weevil?

Ken Wise,

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Monitor alfalfa weevil weekly from mid to late-April through June. Because weevil populations can build up over the life of the alfalfa stand, monitoring fields that are two or more years in production is critical to determine infestation levels. Start weekly field sampling in fields at about 350 degree-days (base temperature 48F) which is about mid to late April in most years, but not this year!

·       Pick 50 alfalfa stems at random throughout the field.

·       Look for the small "shot holes" in the leaves that indicate that larvae are feeding.

·       Record the percentage of alfalfa stems that show the "shot hole" feeding damage in the top 3 inches of the canopy.


Before the first cutting, if 40% of the stem tips show feeding damage, you are at the "action threshold". The good thing is that alfalfa weevil can generally be controlled by harvesting. If you reach an action threshold within a week of your normal 1st cutting date, early harvesting will help avoid economic, yield, and forage quality losses. Alfalfa weevils only have one generation per year and are typically not a problem after first harvest. Occasionally, weevil can damage alfalfa re-growth after harvest. This damage may be more evident in the windrow areas, and can be more noticeable under cool or droughty weather conditions. If you find that 50 percent of the new growth is damaged, with many small larvae present, a chemical control may be warranted. For more information on alfalfa weevil checkout our online publication: IPM for Alfalfa Weevil

Practice Soybean IPM Before Planting

Julie Dennis,

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Fungicide treated soybean seed is generally not needed in NY when high quality seed with a germination rate of at least 85% is planted. Check your field records from the last time soybeans were in your planned fields - was there damping off (rotting seedlings), or Phytophthora root rot? If yes, fungicide seed treatment may be warranted. Plus, the earlier the planting (and the cooler and wetter the soil), the more likely the field is to benefit from a fungicide seed treatment.

Insecticide seed treatments may help control seed corn maggot and wireworms in soybeans, but because soybeans readily compensate for gaps in the rows, a small stand loss from these insects is not usually a concern. Insecticide seed treatments on soybean for soybean aphid (SBA) management have not been shown to adequately control soybean aphid (SBA) in university research trials across soybean-growing regions of the US. (We’ll give many more details about SBA as the season progresses). Although we saw bean leaf beetle in NY for the first time last year, they were not present until late in the season. Recommendations for soybeans in the Midwest may talk about using seed treatments for protection from bean leaf beetle, but please remember that this is not relevant for soybeans in NY!

Scouting for early season disease and insect pests should begin as soon as soybean plants start emerging. We will provide more information about specific seedling disease and insect pests, and how to scout for these pests, in upcoming issues of this report.

Barn Fly Management – Not too early to start…

Keith Waldron,

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Summer will soon be here and with it the fly season for dairy producers. Confined livestock facilities can contain perfect habitats for house and stable fly populations to develop. The good news is these conditions, when controlled, can help minimize 90% or so of the potential fly problem. A little management time each week will pay big dividends as the season progresses.

Sanitation, Sanitation, Sanitation! Staying ahead of fly populations 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.

We’ll have more articles on fly management in upcoming issues of the weekly pest report. One question that has been raised lately regards the use of natural enemies in the fly management program. A variety of biological control agents occur naturally in the typical dairy barn. These include various predators of house and stable fly eggs, larvae and adults. When sanitation, aka clean out and other activities that enhance dry conditions are used effectively, natural enemies can more easily keep up with what fly populations remain and can be quite effective at reducing their numbers. The key is to employ sound sanitation, early and as often as practical, as the first line of defense for mitigating fly populations. Common fly predators include predaceous mites, rove and Carcinops beetles, parasitoid wasps, and fly diseases. Parasitoids, the small wasps that attack fly pupae, are quite effective at reducing fly populations. These tiny wasps, however, can take up to three times longer to develop than the house fly. This is the reason their populations can use a “jump start” early in the season to reach the numbers needed to head off house fly problems. For those wishing to use parasitoids to enhance their biological control efforts NOW is the time to begin releasing the wasps in barns and calf housing areas. Parasitoids should be released close to their prey, i.e. in and around potential fly breeding habitat.

A number of insectaries advertise house fly parasitoid species for use in confined animal facilities. Our experience at Cornell has shown a need to obtain climatically adapted strains.

The source of parasitoids we have worked with in our area is IPM Laboratories in Locke NY.  (315.497.2063). To the best of my knowledge this is the only Northeast US commercial insectary offering the dairy fly parasitoids (Muscidifurax raptor and Musicifurax raptorellus).

If producers are interested in trying a source from outside the NE, it is strongly recommend that they ask the supplier “Is the parasitoid they are purchasing climatically adapted to the northeast?” We are still in the relatively early stage in our understanding of how to use biocontrol to full advantage in fly management programs. Should producers purchase a product from outside the NE, we would be very interested in their thoughts and feedback on how well it is working for them.

To help evaluate how well fly management efforts are working use some means, such as spot cards, to monitor fly populations over time. The spot card method helps provide an objective means to gain information and feedback on the effectiveness of their overall fly management program. Spot cards are 3X5 index cards placed at 5-10 locations throughout the barn in areas where flies can be seen resting such as walls, rafters, poles, etc. Date and identify the location (number) of the card and install cards out of the reach of animals. Change the cards weekly. Our guideline has been 100 spots per card per week indicates a fly problem. Search the area close to location of the card for fly breeding habitat. Clean as necessary. Watch and compare spot card counts the following week. For more information on this technique see: Integrated Management of Flies in and around Dairy and Livestock Barns.

Growing Degree Days for NYS

Ken Wise,

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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


CURRENT Accumulated Growing degree days (48F Base)
March 1 -May 14, 2007



Base 48 F

Base 50 F







Clifton Park












Clipboard Checklist

Keith Waldron,

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Clipboard Checklist


* 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

      - evaluate 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.

• Timothy stands: check fields for symptoms of cereal rust mite

• Storage areas cleaned and ready to accept upcoming harvest?


• Field preparations, planter ready, Rhizobium inoculum?

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: tractors, tillage implements, planters, etc. as they are cleaned and serviced.

• Service corn planter as needed. alfalfa harvesting equipment, and tillage implements

• Soybean planter and alfalfa harvesting equipment ready?

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

Contact Information

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Julie Dennis: IPM Area Educator, Livestock and Field Crops, Western NY
Phone: (315) 331-8415
Fax: (315) 331-8411

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