Weekly Field Crops Pest Report 2009

View from the Field

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Alfalfa weevil is still being reported in alfalfa fields this week across the state. Because of the cooler weather alfalfa weevil development may have been delayed. Because of this delay alfalfa weevil may cause damage in re-growth alfalfa. The threshold for re-growth is 50% tip feeding on the alfalfa.

Potato leafhopper was found in both Western and Eastern New York this week. If Alfalfa weevil and potato leafhoppers are both infesting fields at the same time can cause 2 stresses at the same time. Make sure you get out and scout your fields.

Brian Aldrich confirmed a field with wheat streak spindle mosaic virus (WSSMV) in a winter wheat field in Cayuga County. WSSMV symptoms are yellow-green dashes or streaks with tapered ends, running parallel to the leaf veins. A soilborne fungus that attacks the roots of wheat in the fall transmits WSSMV. Symptoms often show up on plants in wet soils, but excessive moisture in the spring is not required for infection to occur. Cool spring temperatures like we are now experiencing are ideal for continued development of WSSMV. Wheat is at the greatest risk from losses to WSSMV when there are prolonged cool periods in April and May. As temperatures warm, plants usually outgrow the disease. Click here to see photos of WSSMV

There are several reports of leaves on field corn turning purple. This is due to cold soil temperatures. When the weather starts to warm some and the soil temperature increases the corn lose the purple color.

Weather Outlook

Drew Montreui
NOAA NE Regional Climate Center, Cornell University

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The week from June 2 to June 8 saw a continuation of the below normal temperatures. Areas to the east of I-81 seemed to generally be 0 to 3 degrees cooler than average. West of I-81, temperatures ran 3 to 6 degrees below average, and some places in the north were as much as 9 degrees below normal. Precipitation during this period was almost non existent, with all areas receiving under 0.5” and some areas along Lake Ontario and in the Adirondacks getting no rain. There was some rain the last 2 days that is not reflected on the current maps, but it was generally less than 0.5” and south of I-90.

Base 50 Growing Degree Days were generally in the 50-75 range for that same June 2-June 8 period. Some areas in the north and southwest parts of the state got less than 50. For the season, this puts most areas between 300 and 400, with 200-300 in the north with pockets of less than 200. Compared to last year’s values, almost evenyone is within 3 calendar days of last year, or about 75 growing degree days. The areas ahead of last year are in the south, while areas north are behind. For the season, areas south of I-90 are a couple of calendar days ahead of normal, with some areas in the southeast as much as a week ahead. North of I-90, most areas are 3 to 7 days behind, with deficits as high as 10 days in the Tug Hill region and portions of the Saint Lawrence Valley.

For the weather, an area of low pressure departed the region yesterday after producing thunderstorms with hail over portions of southeast New York. High pressure will move in briefly for today, before another low brings rain and a few thunderstorms tomorrow. This low will be slower to move out, keeping showers around Friday, especially for the eastern regions. Highs Friday will be in the mid 70s in the north and west, with upper 70s south and east. High pressure and sunshine will come in for Saturday and Sunday. Temperatures Saturday should peak in the low to mid 70s, with lows in the mid 50s. Sunday will have highs in the low 70s in the west, with mid to upper 70s in the east. Lows will be in the low to mid 50s. A cold front will bring a chance for showers on Monday with highs in the upper 70s and lows in the mid 50s. There could be a couple showers Tuesday, with highs in the mid to upper 70s and lows in the mid 50s. Generally 1/4” to 3/4” of precipitation can be expected, with some areas in the east getting over an inch. The 8 to 14 day outlook keeps the cool weather around, but it does look as if temperatures won’t be quite as cold as they have been. Precipitation should be about normal.

Soybean Emergence and Stand Counts

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Soybean growth is moving along slowly but it will soon be time to assess soybean stands. The to-do list includes estimating plant populations and investigating the cause of missing plants in the rows.

The following table summarizes a method for estimating plant populations. Count the number of plants in the given length of row based on the row spacing, and then add 3 zeros. (For example, if 165 plants are counted, your estimated plant population is 165,000). Repeat this for the number of rows in your planter or drill, and repeat in 2 more areas of the field.

When skips are seen in the rows, it is time to do some digging. Are seeds planted too deep such that plants are still emerging? Was the planter or drill acting up? Are damaged seeds or seedlings seen? If seeds are mushy or rotten, a seed or seedling blight might be the problem. See Ken’s article for detailed descriptions of disease problems in soybean seedlings in the May 29^th issue.

If seeds, stems, or roots show signs of feeding injury, the usual suspects are seed corn maggot, wireworm, or white grub. Risk from seed corn maggot is greatest if there is high organic matter on the soil surface, from crop residue or manure, for example. Wireworm and grub threats are usually greatest following a grass or pasture sod.

Stand assessment information gathered this year will help guide decisions about management that may be warranted in future years.

Sampling for Potato Leafhopper in Alfalfa

Ken Wise
NYS IPM

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Scouting alfalfa fields is the key to early detection of potato leafhopper infestations. Use a 15-inch diameter sweep net to determine the potential risk a potato leafhopper infestation may pose to your alfalfa. Scouting for potato leafhopper starts after the first cutting of alfalfa (about the first part of June) till the first fall frost. You will want to use a potato leafhopper sequential sampling plan to determine if an infestation requires management or not. The first thing to do is determine the height of your alfalfa. Smaller plants are more vulnerable to potato leafhopper; thus there are different action thresholds for different heights of alfalfa. The second thing you will need to know is how to sample for potato leafhopper. A sample consists of a set of 10 sweeps of the net. A sweep is one pass in front of you as you walk through the alfalfa. The return swing is counted as another sweep. Sequential sampling reduces the time spent in each field and tells you whether to treat (management action) or not treat (no management action). Sequential sampling is particularly helpful in minimizing time required to make a management decision in situations where PLH populations are very high or very low. Use the following chart to determine potato leafhopper infestation levels.

N= No management needed at this time

T= Management needed as soon as possible    

Write down the number of potato leafhoppers for each sample taken on the card. Add each sample to the next, keeping a running total of potato leafhoppers. You will need to take at least 3 samples using the sequential sampling method. On the sequential sampling card “N” is defined as no treatment (no management) needed at this time and “T” is defined as treatment (management) needed within in a week. If the sample is smaller than the “N” number stop and scout 7 days later. If the number of leafhoppers is larger than the “T” number then management action needs to be taken within a week. If the number of potato leafhoppers fall between “N” and “T” then continue and take the next sample till a decision can be determined. A guide with a printable version of the sequential sampling chart can be found at the Potato Leafhopper on Alfalfa Management Guide.

NYS Soybean Rust Update

Mary McKellar
Department of Plant Pathology,

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The first detections of soybean rust on soybean in 2009 were made in Louisiana and Alabama on June 4th and 8th respectively. This is the earliest detection of soybean rust on soybean in both of these states. Limited periods of precipitation over the next several days will lead to spore deposition in the affected areas in the Florida panhandle, Georgia and the Gulf Coast. 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. Please visit us again for future updates on soybean rust in the U.S. and New York state.Updated June 9, 2009

NY State Soybean Rust Hotline: 607-255-7850

NYS Soybean Rust Website

USDA Soybean Rust Website

Fusarium head blight (FHB) Update

Gary Bergstrom
Extension Plant Pathologist, Cornell University

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The majority of New York’s winter wheat crop reached anthesis during the interval of May 31 to June 8.  The predicted risk of Fusarium head blight (FHB) was low to moderate for New York State during this interval.  Wheat planted in late October into November will initiate flowering by the end of this week.   Wheat is most susceptible to infection by the fungus that causes Fusarium head blight (scab) during anthesis (when anthers first emerge) and at early stages of grain development.  It is important  to note when your wheat reaches anthesis and to check the Prediction Center each day.

Fusarium Head Blight Risk Assessment Tool

Growing Degree Days in NYS

Ken Wise
NYS IPM

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CURRENT Accumulated Growing degree days (48F Base):

March 1 -   June 10, 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

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
* 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, weed escapes?
* Storage areas cleaned and ready to accept hay harvest?

Corn:
* Determine plant populations, make notes on emergence problems, plant vigor, growth stage
* 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 (heading? anthesis?), insect problems (cereal leaf beetle, armyworm) and foliar / head diseases
* Evaluate crop for adequate stand and plant vigor

Alfalfa & Hay:
* Monitor alfalfa seedings for weeds, insects & diseases.
* Check regrowth of established alfalfa stands for alfalfa weevil, potato leafhopper, weed and disease problems.
* Check windrows of recently harvested alfalfa for signs of alfalfa weevil feeding damage and weevil life stage (instar cocoon).
* Storage areas cleaned and ready to accept incoming harvest?

Soybeans:
* Evaluate stand emergence - seedling blights, seed corn maggot, weed assessment, 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
* 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 and soybean planter as needed. alfalfa harvesting equipment, and tillage implements
* 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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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