Weekly Field Crops Pest Report 2006

View From The Field

Western NY and Finger Lakes
Julie Stavisky, NYS IPM

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Eastern NYS
Ken Wise, NYS IPM

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Scouting reports from the TAg team in the Skaneateles Lake Watershed Program (Onondaga and Cayuga counties) show high adult corn rootworm populations in third-year and later corn.  Most of the fields being scouted are over threshold.  In soybeans, Erin Hull, the scout for this TAg program, reports that downy mildew is present but not severe, and that aphid numbers remain low.  The highest infestation she observed on a single plant is 150 aphids, still well below the 250 aphid-per-plant threshold.

White mold is evident but not yet severe in limited fields in Seneca and Cayuga Counties.  It is crucial for soybean producers to be watching vigilantly for this disease so that it is not a surprise at harvest time.  Noting the presence of this disease is necessary for planning rotations in infected fields.

Potato leafhoppers are over threshold in alfalfa in Ontario County.  Threshold populations were counted within 3 sets of sweeps.  Plus, my boots were covered with PLH nymphs when I left the field!  Download a PLH sequential sampling form here (309k pdf).

This week at the SUNY Cobleskill Farm potato leafhopper populations are below threshold but higher that they have been all season. Many of the corn fields show corn rootworm damage as seen on the picture below:

This corn that had fallen over and grew in a curved fashion is called J-necking. This occurs when the larvae of corn rootworm have eaten the roots of the plant and the corn cannot stand anymore. When it falls over it grows back up to the sunlight giving the corn plant the “J-necked” shape.

This week at the Cornell Research Farm in Valatie I could not find any potato leafhoppers in 2 to 3 inch alfalfa. The corn plots that do not have electrical fencing show some deer damage on the ear of corn. While the soybeans I monitor look good I have seen a little bit of downy mildew. Early symptoms of this disease appear as pale green to light yellow spots on the leaves.

As downy mildew progresses the lesions increase in size and turn pale to light yellow. When leaves become severely infected they turn yellow, brown, curl around the edges and drop off prematurely. The soybean pod may also become infected, but there are no symptoms on the outer surface. The pod may have a white moldy fungus in the interior surface and may infect the seed. Oospores survive within leaf residue or in seed. Cool to mild temperatures and high humidity favor this disease. Management of downy mildew can be accomplished by crop rotation and clean tillage of fields with infested residue. There are also some soybean varieties that are resistant to downy mildew.

NYS Soybean TAg Program

Julie Stavisky, NYS IPM

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With funding from the Northeast Soybean Promotion Board, four teams of soybean producers are meeting on a monthly basis in NY in 2006 in an on-farm, season-long soybean IPM education program based on the TAg Team model. The objective of the on-farm programs is to provide a forum for discussing all agronomic and economic aspects of soybean production in New York State, with an emphasis on the identification and management of critical pests including Asian soybean rust and soybean aphid. Visit our Tactical Agriculture page for more information about the TAg program. As a result of education and increased awareness, including our efforts through soybean TAg team participation, producers are more vigilant than ever toward pests in their soybeans.

We are working with our cooperative extension colleagues (Jeff Miller, Oneida County; Mike Stanyard, NWNY Dairy and Field Crops Team; and Mike Dennis, Seneca County) on the Soybean TAg program for the second year in a row. Early season meetings were held to introduce the participants to the soybean TAg program and to administer a pre-questionnaire to assess current pest and crop knowledge.  While many of the questions concerning basic agronomic concepts were answered correctly, few participants were able to answer questions about soybean pest identification and management or the timing of management actions in relation to stages of plant growth and development.  We are using these results to help shape our curriculum.

During the second set of meetings in mid June, we conducted stand counts, provided an update on soybean rust development in the southeast, practiced soybean aphid scouting (including monitoring for natural enemies), and conducted a weed assessment. Low numbers of soybean aphids so far this season have been a relief to participants! An emphasis is placed on understanding plant growth stages to help participants understand vulnerable stages in plant growth and development, and to correctly time management actions, if management is necessary.  The most recent meetings were held in mid to late July.  We discussed and observed foliar diseases of soybean, with an emphasis on how to distinguish each disease from soybean rust.  An overview of the biology and identification of white mold was introduced.  Plans are underway for the next meetings to be conducted in mid to late August.  Given our significantly wetter than average July, white mold is anticipated to be a major topic of discussion. At each meeting, we have shared observations from scouting one field of each producer (scouting of one field per producer is provided through the program).

The program is providing valuable information to producers and to us in NYS IPM and CCE. It is serving as a forum of discussion for a wide range of soybean producers, including large-farm field crop producers, dairy producers with some acres of soybeans, organic producers, and vegetable producers with soybeans in their rotations.

Deer and Bird Damaged Corn Ears: Open the Door

Ken Wise, NYS IPM

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This week I have seen an excess of corn ear damage created by deer and some birds. The husks covering the corn were pulled back and about a third of the grain was gone. Some of the ends of the ears were bitten right off by deer. In addition, the open husk can allow a variety of diseases to infect the ear of corn. Some of these diseases might be: Common smut, Fusarium ear rot, Gibberella ear rot, Diplodia ear rot, Cladosporium ear and kernel rot, and more.

Signs of Alfalfa Snout Beetle: Look for in the Fall!

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Alfalfa snout beetle (ASB) is a very serious root-feeding weevil that is found only in northern New York State and southern Ontario. Adult ASB feed on leaves and stems, and the larvae feed on the roots of alfalfa and clover. ASB is one of the few pests that can completely destroy an alfalfa field. Some growers have been forced to grow other forages than alfalfa because of the destructive damage by this insect to alfalfa and certain clovers. Adult ASB are mottled gray, humpbacked, 1/2 inch long, do not fly, and are all females. Adult ASB emerges in the spring to feed on new shoots from the alfalfa crown. (Note: above ground active adult ASB is only a small portion of the infestation). ASB lives under the soil surface for about 2 years. When adults emerge in the spring they migrate in mass numbers often in a northeast or northwest direction. Legless white larvae, are a 1/2 inch long, can be found within a foot of the soil surface in mid to late summer and feeding on alfalfa roots. Larvae feed on side roots, and girdle the main taproot causing death to the plant. ASB root feeding and systemic root diseases can cause alfalfa stands to exhibit signs of early senescence in the fall. In counties with confirmed ASB infestations, fields showing these symptoms should be sampled for ASB. If snout beetles are present their larvae should be easily found on alfalfa tap roots. THIS MEANS CHECK NOW! During late summer and early fall the larvae move deeper in the soil where they spend the winter. The following spring the larvae move 10-12 inches from the surface, pupate by mid-summer and become inactive adults, which remain in the soil until the following spring. To combat the ASB the only line of defense is to practice intensive crop management. Rotation with susceptible and non-susceptible crops is very important. Rotation limits the ASB from developing large infestations in field. ASB has host plants other than alfalfa that make eradication impossible. Host plants for ASB are: alfalfa, red clover, dock, wild carrot, quackgrass, and white clover. Non-host cultivated crops for ASB are: corn, wheat, oats, soybeans, potatoes, and birdsfoot trefoil. Growers should plan to crop alfalfa for 2 to 3 seasons, using clear seedlings, and then rotate with non-host cultivated crops for 2 or 3 successive years. New infestations can be caused by transporting ASB to other farms, fields or homes. Take precautions to limit artificial transport of ASB by cleaning equipment between fields and farms. Limit transporting possible infested hay bales, gravel and soil to non-infested sites. Research is continuing to identify sources of alfalfa root resistance to ASB (Don Viands, Julie Hansen and Elson Shields). The use of an insecticide for the control of this insect has not been shown to be effective

Livestock Fly Pest Update

Cornell Veterinary Entomology Program and Keith Waldron, NYS IPM

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On Pasture: During the first week of August the stable fly populations are still present in peak numbers affecting animals on pastures.  Horn fly populations extensive on local herds in central NY.  The manure collected from pastures has demonstrated large maggot burdens, suggesting that next week there will be a lot more face and / or horn flies present.  Dung beetle populations appear to be stable.

In/around barns: House fly and stable fly populations have increased in past 2 weeks, responding to recent rains and high temperatures, both  environmental conditions favorable for fly development. Stable fly populations have been enhanced by migrating stable flies brought in by recent weather fronts. Moist (warm, soupy) organic matter near edges of bunk silos, manure storage areas, and similar locations have been suitable for development of rat tail maggot populations (See photo). Although not harmful to animals, rat tail maggots can cause potential problems as they migrate en mass away from wet areas seeking dryer locations to pupate.  Problems occur if maggots enter the barn or milk house. Rat tail maggot adult flies are similar in appearance to fuzzy bees.

For more information on dairy fly pests visit the website for Veterinary Entomology, Department of Entomology, Cornell University

Soybean aphid update

Keith Waldron, NYS IPM

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Soybean aphid (SBA) populations remain low (0-40 SBA's per plant average) in most SBR sentinel plots being monitored across NY. Soybeans are typically at R4-R5 growth stage.

Some sites in central (Finger Lakes) and western NY regions are reporting the presence of "white dwarf" soybean aphids among the normal SBA forms. In central NY, there have been isolated areas where white dwarf populations have contributed to a total SBA population exceeding the 250 SBA / plant threshold. Some of these fields have been treated with an insecticide.

Central NY cooperators have reported activity of fungal entomopathogens providing effective biological control of soybean aphids

For more information on soybean aphid and soybean rust activity in NY see the USDA Public PIPE website.

Growing Degree Days in NYS

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Accumulated Growing Degree Days for March 1 to August 2

*indicates missing data

Source: NEWA

Clipboard Checklist

Keith Waldron-NYS IPM

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General:

* Maintain crop records by field, including crop condition, inputs, observations, issues, concerns, etc.

* Check grain storage bins for temperature, moisture and air flow.

* Mow around storage bins, barn and farm facilities

Established Alfalfa & Hay:

* Monitor for potato leafhopper- harvest early or spray on basis of need.

* Monitor for diseases, particularly Verticillium wilt, record information on disease species and location for future cropping decisions.

* Monitor for Phytopthora root rot in fields recently flooded or subject to ponding.

Alfalfa Seedings:

* Continue monitoring for potato leafhopper, weeds and diseases.

* Monitor fields for weeds and diseases: record information on type and location for future cropping decisions.

* Monitor for Phytopthora root rot in fields recently flooded or subject to ponding.

Small Grains:

* Check grain storage bin for temp, moisture, air flow, drying conditions.

Corn:

* Monitor corn rootworm adults at silking.

* Observe corn for crop growth and condition, weeds, foliar diseases, lodging and fertility

Soybeans:

* Monitor for crop condition and growth stage, white mold, soybean aphids, natural enemies, foliar diseases, soybean rust

* Monitor for Phytopthora root rot in fields recently flooded or subject to ponding.

Livestock:

* Continue manure management and release of biological control agents (parasitic wasps) for house fly and stable fly control in barns

* Monitor young stock for cattle lice and mange mites

* Check condition of pastures and animals on pastures

- Evaluate need for face fly and stable fly control measures, adjust paddock rotation as needed.

Equipment:

* Provide annual maintenance to fertilizer and pesticide application equipment.

* Note any repairs to harvesting equipment as they are cleaned and lubricated.

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