Weekly Field Crops Pest Report 2009

View from the Field

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Mike Stanyard found soybean aphids (SBA) on buckthorn this week. Buckthorn is the alternative winter host for SBA.  He is finding of alfalfa weevil (AW) larvae in several fields in NW New York. Mike states that cereal leaf beetle can be found in oats with adults beginning to lay eggs on oat plants. Mike suggests watching corn and other field crops for cutworms in fields because the migration of adults on weather patterns from areas to our west. Cutworm moths will catch rides on the storms and lay eggs in fields with grassy weeds. 

I found 1^st and 2^nd instar AW larvae at the SUNY Cobleskill Farm this week. Most the larvae found were on southeast facing slopes. Fields that face the south warm more quickly and AW can develop faster than in other fields. On the lower leaves of alfalfa I was starting to see spring black stem. See article below for more information on early season alfalfa foliar diseases.

Weather Outlook(5-14-09)

Art DeGaetano
NOAA NE Climate Center, Cornell University

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Most of the state saw temperatures that were within a degree or two (plus or minus) of normal last week. Despite this temperatures dropped below freezing at many upstate locations on Tuesday and Wednesday. 

Less than 50 base 50 degree days accumulated during the week, except in the extreme lower HudsonValley and Long Island which saw between 50-75 degree days.  Seasonal totals now range from 300 near New York City to 200 in Rockland and WestchesterCounty.  Less than 150 degrees days have been observed across much of upstate NY.  These accumulations are about two weeks behind last year along the Lakes, but about 10 days ahead of last year in the southeast part of the state.  Compared to normal, the accumulation of degree days is about a half a week (35 degree days) ahead.

The western part of the state saw between 0.5 and 1 inch of rainfall last week.  Totals were higher downstate and in the HudsonValley where 1-2 inch totals were common. Abnormally dry conditions have characterized the growing season so far across the Southern Tier, where less than 50% of the normal precipitation has fallen over the last 30 days.

Unsettled conditions today will improve briefly on Friday and early Saturday before high pressure exits the coast allowing a warm front to approach NY from the southwest on Saturday.  Warm temperatures are in store for Saturday with a good chance of afternoon showers and thunderstorms.  A cold front will move through late Saturday bringing cooler temperatures and continuing showers into Sunday particularly to the east and across the southern Tier.  Highs Sunday will only be in the upper 50s.

A drying trend seems in store for most of next week as high pressure remains over the region. Temperatures will slowly recover to near normal by Wednesday with high in the 70s and low in the upper 40 to mid 50 across the state.  Beyond that temperature should remain near normal and it looks like it will be on the dry side with the main storm track to our south.

Soybean Pest Season Opener

Keith Waldron
NYS IPM

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USDA estimates the planted soybean acreage in New York will be the largest on record.

Soybean fields are beginning to green up with 2 leaf stage rows of seedlings already visible in some areas of the state. So far there have been no soybean pest related issues reported in NY this season.

Too early for soybean rust in NY, however the disease has been detected overwintering on kudzu in the Southeastern U.S. Currently in the gulf coast region ( Alabama, Mississippi and the panhandle of Florida), soybean rust disease incidence and severity on kudzu has been reported as low to medium. For the latest information on soybean rust in NY see:  www.plantpath.cornell.edu/soybeanrustny/

Soybean aphid (SBA) problems have been relatively localized in recent years with larger populations seen in the central Finger Lakes soybean production areas. Soybean aphid numbers were low in 2008. Fields will bear watching to see if soybean aphid becomes an issue in 2009.

This week CCE educator Mike Stanyard had the opportunity to work with PennState University entomologist Shelby Fleischer to survey buckthorn for signs of over-wintering soybean aphids in Wayne county (Finger Lakes region of upstate NY).

As of Tuesday of this week, they had observed young SBA's on buckthorn in several areas surveyed. They estimated overwintering SBA eggs hatched about 2 weeks ago.  The first generation of young were found in very young partially expanded buckthorn leaves. Mike reports these young soybean aphids were a dark green color, extremely small, about the size or smaller than the dot left by a #2 pencil, with 2 small dark spots on their hind end. Another hint SBA young were present on the buckthorn branch was the presence of ants tending the aphids.

See close up photo of very small soybean aphid young being tended by ants on young buckthorn leaf.

(Photo by Amanda Bachmann, PSU Entomology).

We would be interested to hear about soybean pest observations from other NY readers as the season continues.

Early Season Foliar Diseases of Alfalfa

Ken Wise
NYS IPM

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Spring Black Stem: is favored by cool and moist weather in early spring. Symptoms appear as irregularly shaped brown to black spots that can merge to form a larger blotch. This disease can infect the petiole, form elongated blackened areas on the stems, and may be a contributor to a crown rot. Spring Black Stem

Common Leaf Spot: proliferates when the weather is cool and wet. This disease first develops on the lower leaves near the soil surface and then progresses upward through the canopy. Common leaf spot appears as small, circular, dark brown to black spots, about 1/16 inch in diameter. When observed through a hand lens, tiny raised, light brown disk-shaped fungal fruiting bodies are visible in the center of mature lesions. See photo at: Common Leaf Spot

Leptosphaerulina Leaf Spot (aka “Lepto”): is also favored by cool and moist weather in early spring and late summer to early fall. The lesions usually start as small black spots and enlarge to oval or round “eyespots” 1/16 to 1/8 inch across. As lesions develop they become light brown or tan with dark brown borders; often surrounded by a chlorotic (yellow) area. This disease primarily attacks young leaflets but may also attack petioles and other plant parts. See photo at: Leptosphaerulina Leaf Spot

Downy Mildew: causes leaves to become blotched or chlorotic (light green or yellow). Many times young leaflets can become distorted. Often a dark purplish-gray fungal mat covers the underside of the leaves. This disease is common early in the spring. See photo: Downy Mildew

While alfalfa leaf spots may be easily found in most stands the real impacts for this harvest would be if 30% or more of the leaves on plants were shed as the result of infection.

For more information view our on-line management guide: Alfalfa Diseases (Leaf Spots) Management

Quantifying Row Crop Plant Populations

Keith Waldron
NYS IPM

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Weather outlook for the next week looks like temps below normal and above normal precipitation. These conditions may slow seed germination or seedling emergence. Slower emergence can favor some emergence problems such as seedling blights and seed corn maggot. Checking emergence of corn populations is critical to detect stand problems early.

Seeing gaps within rows? Check for proper soil pH? N-P-K matched to soil test recommendation? Nice seedbed preparation? Timely planting? Plant Population? - Check?

How many corn seeds did you plant and what did you get?
It's important to evaluate stands early to determine if the optimal plant population has been achieved. A good stand or a replant situation? One EZ method for determining plant populations is to count the number of plants per 1 / 1,000th of an acre. Determine the length of row you'll need to count plants in by referring to the row width table below. Then determine the average of three sets of emerged plant counts found at several locations throughout the field to get the average number of plants per acre. Finally, determine the average number of plants found in the length of row sampled and multiply by 1,000 to get the average plant population.

Locate wheel tracks and make observations for each row planted. Check at least three areas within the field for consistency and to determine if all planter boxes were operating well.

A 10% reduction in number of plants observed vs number of seeds dropped is not uncommon. Large deviations from what was expected can signal a variety of potential problems. If your plant population counts are not up to snuff, sometimes waiting a few days and re-doing the estimate can make a difference if there is uneven germination from cool temps or variations in seeding depth. Other potential problems can be related to poor seed germination, planter calibration, performance and planting associated problems, poor soil conditions, seed rots or seedling diseases, seed corn maggot, wireworm, white grubs, birds, mice, and other factors.

Alfalfa Weevil Degree Days Update

Ken Wise
NYS IPM

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

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

CURRENT Accumulated Growing degree days (48F Base)

March 1 -   May 13, 2009

*Indicates missing data

Soybean Rust Update

Gary Bergstrom
Cornell University

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On April 24th, soybean rust was detected on kudzu in Gadsden and Leon counties in Florida. The disease had been detected in both counties on kudzu earlier this year but had not been observed since January.

Soybean rust scouting continues in the Southern U.S. and Mexico. Soybean sentinel plots continue to be established in the Gulf Coast states and kudzu is breaking dormancy throughout the region. In 2009, soybean rust has been found in five states and 17 counties in United States, and in two states and five municipalities in Mexico.

In 2008, soybean rust was found in 16 states representing 392 counties in the United States. Rust was also reported in 14 municipalities (counties) across four states in Mexico.

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:
*Finish corn planting by May 15, if soil conditions allow
* Determine plant populations, make notes on germination problems
* Gaps in row? Check for seed corn maggot, wireworm, white grubs, cutworms, 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, cereal leaf beetle and other insect and disease problems
* Check wheat for powdery mildew and soil borne wheat mosaic virus (susceptible varieties such as Harus and Jensen)
* 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?

Soybeans:
* Field preparations, planter ready, Rhizobium inoculum?
* Check emergence and early season insect and disease pest issues and weed escapes

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 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