Weekly Field Crops Pest Report 2009

View from the Field

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Alfalfa weevil (AW) infestations have increased across New York. Jeff Miller ( CCE Oneida County) reports AW damage in fields. He also indicates one field was over the economic threshold of 40% tip feeding. Mike Stanyard (NW NY Dairy and Field Crops Team) reports several fields over threshold for AW. Mike also reports a winter wheat field with wheat leaf rust.

Wheat leaf rust is disseminated on airborne spores and travels on storms for the southern part of the United States. Leaf rust is proliferated during warm and humid weather with thunderstorms in Late May and June. The symptoms of the wheat leaf rust are that lesions are small, circular, and vivid orange in color. The rust may occur on stems, but are most common on the upper surface of the leaves. When heavily infected, the whole leaf will die. Once leaf rust is seen in wheat, it can develop very rapidly. Rapid development occurs between 60^o and 80^o F when moisture is not limiting. The 2 ways to control the disease is to select resistant wheat cultivars or use a fungicide. For more information on wheat leaf rust see the Cornell Guide for the Management of Field Crops: Managing Diseases of Small Grain Cereals.

Brain Aldrich (Cayuga County CCE) reports a winter wheat field over economic threshold for cereal leaf beetle. This field was treated with on insecticide.

Weather Outlook – May 29, 2009

NOAA Northeast Climate Center, Cornell University

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Temperatures last week were slightly above normal, with much of state seeing temperatures three to six degrees warmer than average. Areas in the Tug Hill Region and North Country were closer to normal, but still generally warmer. Precipitation was pretty scarce once again, with most of the state receiving less than an inch of rain. The one exception to this is the Eastern Southern Tier down into Southeastern New York, where some thunderstorms over the weekend pushed rain totals between one and two inches. Under half an inch fell across Western New York and the North Country.

There were 75 to 100 base 50 growing degree days for most of the state in the last week. The higher elevations of Southern New York were slightly less, along with the Adirondacks and North Country, with all those areas getting 50 to 75. For the season, this push the total number of growing degree days to between 200 and 300 for all but the northern part of the state, where there have been 100 to 200. Compared to last year, most areas are now 3 to 10 days ahead, with some areas in the Southern Tier as much as two weeks ahead of last year. Areas in the St. Lawrence Seaway are just behind last year’s values. The current seasonal levels in comparison to normal are about 3 to 7 days ahead, except in the Tug Hill and North Country, where they are a few days behind.

The weather is looking a little more active in the upcoming week. A storm system has been affecting the state for the past two days and will continue to bring a chance for rain today into early Friday. This low will depart tomorrow, with the chances for sun increasing the further west you go. A weak high pressure will build in for Saturday, with highs within a few degrees of 70. Sunday looks cooler, with highs in the upper 50s in the north ranging to the low 70s Downstate. Most areas should end up in the low to mid 60s. Both days could see some scattered showers. Another storm system will bring better chances for rain Monday and Tuesday. Highs Monday will mostly be in the mid to upper 70s, with temperatures Tuesday ranging from the low 60s in the west and north, to near 80 Downstate. Wednesday will likely be dry, with highs mostly within a few degrees of 70. Low temperatures throughout the period should range from the upper 40s to low 50s on average. Rainfall totals over the next 5 days look like they will be highest in the north, where 1.25” to as much 2” is possible. The rest of the state should get from 0.5” to 1.5”. The outlook for the next 8 to 14 days is calling for near normal precipitation with below normal temperatures.

Alfalfa Weevil Management: Beneficial Insects Are On Our Side

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Alfalfa weevil larvae have been seen in several locations over the past couple of weeks.  Biological control agents are a significant reason that alfalfa weevil (AW) often remains well below economic thresholds in NY.

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 this devastating pest.  A parasitic wasp lays an egg in an AW larva, thus killing the larva of the pest insect and providing the food source for a growing parasitic wasp. How do we know if these wasps are helping us out in our fields? One of the revealing times to look for alfalfa weevil parasitoids is when they are in the pupal stage. Based on growing degree day accumulations so far this season, the pupal stage is still a ways in the future.  Check out the AW GDD map later in this report to track GDD accumulations in your area of NY.

While searching for alfalfa weevil pupae later this month or in early June, keep your eyes out for the parasitoid pupae, too. Alfalfa weevil pupae can be found inside small net-like, pea-sized cocoons generally found in lower regions of the plant on or 2-3 inches above the soil surface. The alfalfa weevil pupa is surrounded in a white to tan webbing, often associated with a leaf, and a wasp pupa is instead surrounded by a small hard brown capsule-shaped 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

 Pupae (within their cocoons) of parasitic wasps of Alfalfa Weevil

The two most common parasitic wasps of AW in NY are in the genus Bathyplectes.  Their pupae are enclosed within the mahogany colored shells, or cocoons, with white bands (2^nd and 3^rd from the left in the above photograph).  These two parasitoid species tend to lay eggs in the early alfalfa weevil larval stages.  Only a single parasitoid can successfully develop in a host weevil larva.  The two species can be distinguished from each other as pupae.  Batheplectes anurus has a raised white band and the cocoon has the unusual habit of “jumping” when disturbed.  B. curculionis does not have a raised white band, and the cocoons do not jump.

Don’t forget to review the NY alfalfa weevil scouting guidelines in our Alfalfa Weevil Management Guide.

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

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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 DON, a mycotoxin called deoxynivalenol (DON). DON is sometimes called vomitoxin because of the impact on the digestive system of swine and other animals with simple stomachs.  The rejection of infected grain by buyers is the most significant cause for wheat losses to Fusarium head blight.

Scab is caused by airborne spores of the fungus Fusarium graminearum that dwell in nearby or distant 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 not reduced sufficiently by crop rotation or other cultural practices.  Extended periods of warm, moist weather at crop flowering can cause the florets to be infected just after anther emergence, killing the florets and preventing kernels from developing.  Symptoms of scab become visible on emerged heads within weeks 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.

There is a valuable predictive tool available online: the Fusarium head blight Risk Assessment Tool. Gary Bergstrom tells us that this model mainly predicts the likelihood of spore build-up based on temperatures and rainfall amounts prior to wheat flowering. Using the new 24-48 hour forecast weather feature of the model, one can also get an idea of the favorability for actual infection.  It shows us a ball-park of areas to focus our scouting efforts.  Unfortunately, the model does not accurately predict the level of toxin contamination in grain, particularly if there is a sustained rainy spell during grain-fill.

Please note that the only fungicide available in New York for suppression of Fusarium head blight is propiconazole (4 fl. oz. per acre of Tilt or PropiMax applied at 50% of anthers emerged on primary tillers).

Growing Degree Days and Alfalfa Weevil Development in NYS

Ken Wise
NYS IPM

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CURRENT Accumulated Growing degree days (48F Base):

March 1 -   May 28, 2009

*Indicates missing data

Data from NEWA

Growing degree Days for Peak (50%) Occurrence of Alfalfa Weevil growth stage:

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

Source: R.I. Carruthers

NYS Soybean Rust Information Center Update - 5/26/09

Gary Bergstrom
Department of Plant Pathology, Cornell University

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2009 soybean rust detections to date have been on kudzu in Georgia, Florida, and Texas as well as along the gulf coast including Alabama and Louisiana. Soybean rust disease incidence and severity on kudzu in these states has been reported as low to medium. Precipitation in the affected areas may lead to further spore deposition in Georgia, the Florida panhandle and eastern Texas. Scouting in sentinel plots in the Southeastern U.S. continues. Much of the New York State soybean acreage has been planted and begun to emerge. Soybean rust has not yet been detected on soybean in the U.S. in 2009. Please visit us again for future updates on soybean rust in the U.S.

NYS Soybean Rust Information Center

National Soybean Rust Website

Clipboard Checklist

Keith Waldron
NYS IPM

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General:

• Emergency contact information (“911”, local hospital, Chem. Spill emergency contact, other?) posted in central posting area

• Review EPA Worker Protection Standard training and posting compliance needs

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

• Watch for winter annual and other early season weeds, any patches of herbicide resistant weeds?

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

Corn:

• Determine plant populations, make notes on emergence problems

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

• Check no-till fields/fields with high residue or weeds for slug damage

• 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 (flag leaf?, heading?), insect (cereal leaf beetle, armyworm) and disease problems

• Check wheat for foliar diseases, fusarium head blight, wheat rust

• Evaluate crop for adequate stand and plant vigor

Alfalfa & Hay:

• Monitor alfalfa seedings for weeds, insects & diseases.

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

• Storage areas cleaned and ready to accept upcoming harvest?

Soybeans:

• Evaluate stand emergence – seedling blights, seed corn maggot, weed assessment

• Evaluate stand for presence of soybean aphid

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)

Storage:

• Check storage areas (bunk silos, etc.) for readiness to accept first cutting

• Check forage allocation and anticipate feed program adjustments as forages are used up from previous year

• Plan where forages should be stored for optimum allocation for feeding

• Keep areas around storage bins and silos clean and mowed

Equipment:

• 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

PESTICIDE EMERGENCY NUMBERS
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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June 4, 2009 -- Small Grains Management Field Day, Musgrave Farm, 1256 Poplar Ridge Rd, Aurora, NY

July 7, 2009 -- Cornell Seed Growers Field Day, Ithaca, NY

July 15, 2009 -- Weed Science Field Day, Thompson Research Farm, Freeville, NY (morning program)

July 15, 2009 -- NYSABA Summer, BBQ, Musgrave Farm, Aurora, NY 12:00 noon

July 15, 2009 -- Weed Science Field Day, Musgrave Farm, Aurora, NY (afternoon program)

July 23, 2009 -- Aurora Farm Field Day, Musgrave Farm, 1256 Poplar Ridge Rd, Aurora, NY

Aug. 10-14, 2009 -- Soil Health Training Workshop, Ithaca, NY

Contact Information

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

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