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Weekly Field Crops Pest Report 2010

July 26, 2010           Volume 9 Number 14

1. View from the Field

2. Do you know how to scout for Corn Rootworm?

3. Partial Alfalfa Field Harvest Increases PLH risks

4. Soybean Rust Update

5. Clipboard Checklist

6. Contact Information

View from the Field

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The alfalfa at the Cornell Research Farm has turned a yellow to crispy brown from potato leafhopper (PLH) damage. The levels of PLH remain very high. During an alfalfa/field corn TAg meeting with Alex Wright in Rensselaer County a new seeding of alfalfa was just over threshold for PLH. The PLH levels on alfalfa at SUNY Cobleskill were very low this week. I did find both western and northern corn rootworm (CRW) adults this week. The corn was pollinating and the CRW population was under threshold.

Potato leafhopper damage on alfalfa (July 15 at Valatie)

Low incidence of soybean diseases observed this week at the Cornell Musgrave farm, Aurora, NY: Septoria leaf bight and bacterial pustule.

Soybean aphid is remaining at very low populations on soybean in New York. Western Bean cutworm (WBC) in continue to be captured in our monitoring network across the state. New counties for WBC collections this week: Lewis, Jefferson and Washington counties.

Do you know how to scout for Corn Rootworm?

Ken Wise

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Corn after corn? Seeing signs of tassels? For those fields that will again be planted to corn next season… now is the time (beginning thru end of pollination) to begin monitoring for corn rootworm (CRW) populations. CRW eggs laid this summer will overwinter and hatch next summer ready to feed on corn roots. Assessing beetle populations this season provides an indication of the relative risk next years corn crop will have to root pruning by CRW larvae.

Pollination occurs for three weeks and monitoring takes about 20 minutes per field.  You will need to monitor each field once a week until you reach a threshold or until pollination is over. Look for gravid, (i.e. mature, egg laying) corn rootworm female beetles--the plump ones that, when you squeeze their bodies, release white eggs from their posteriors.

Here’s how you scout:

  • Are female beetles present? Mature and capable of egg laying? Conduct the squeeze test (see above) to determine if they are ready to lay eggs.
  • Approach a corn plant carefully because the beetles will fly off if they disturbed too much.
    • Grasp the silk with one hand.
  • Count the beetles on the entire plant.
    • Start counting at the top working down.
    • Gently pull leaves away from the stalk so you count any beetles that may be hiding in the whorls.
  • For each corn plant monitored, record the total number of beetles observed. See the sequential sampling chart below.  Since western corn rootworms are potentially more damaging than their northern cousins, count each western (yellow striped) beetle observed as “one” and each northern (green type) as “1/2”.
  • Check several plants at random (not next to each other!) in several parts of the field.
  • Continue sampling at seven-day intervals until the ear silks are brown, approximately 3 weeks after tassels are first visible, pollination is complete or an above threshold number of beetles are found.
  • If the field is pollinating uniformly a sequential sampling protocol can be used to minimize sampling time. If the field is not uniform rootworm beetles will tend to congregate on pollinating plants making collection of a representative sample more difficult. For information on how to sample for CRW under these conditions see Field Corn Insect Scouting Procedures, page 12.

Using the Sequential Sampling Card for Corn Rootworm

  • Keep a running total (RT) of the number of corn rootworm beetles you have counted on each plant. Each northern corn rootworm has half the value of each western corn rootworm. The western corn rootworm does twice the damage to corn than does the northern. So if you count 3 westerns and 4 northern (2 western equivalent) on a plant you would have a total of 5 beetles.
  • If the number of corn rootworm beetles observed is smaller than the “N” (“Not at threshold”) number stop and scout 7 days later.
  • If the number of corn rootworm beetles observed is larger than the “T” (“At threshold” or “Treat”) number then you need to manage rootworms next year. If the number of corn rootworm beetles observed fall between “N” and “T”, continue sampling additional plants until you finally go over or under.
  • In a very low or very high rootworm population a sampling decision can be made in sampling as few as 3 to 8 plants. For moderate populations more samples may be necessary to insure accuracy.

Sequential Sampling for Corn Rootworm 85k pdf file

For more information on corn rootworm checkout our TAg Educational Materials.

Partial Alfalfa Field Harvest Increases PLH risks

Keith Waldron

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Are PLH in your alfalfa fields? If so, avoid partial field harvests to best manage PLH populations. Clean harvest of whole alfalfa fields is optimal, however our recent stretch of rainy weather has surely messed up more than one harvest schedule sometimes stopping a hay harvest in mid-stride. These partially harvested fields can set the stage for future PLH problems.  In situations where edges or portions of alfalfa fields have been harvested but other areas of the field are left intact watch closely for PLH populations and potential injury.

Adult PLH in the standing portion of the field can easily relocate to the shorter portion of the field and attack the vulnerable regrowth. The shorter alfalfa has a lower threshold for PLH than taller alfalfa so is at much higher risk for injury.

Harvest remaining portions of the field as soon as is practical to minimize PLH population buildup and their easy movement to adjacent portions of the field.

Soybean Rust Update

Gary C. Bergstrom
Plant Pathologist, Cornell University

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On July 16th, soybean rust was found in Gadsden county, Florida on kudzu. Soybean rust has been reported on kudzu from the county of Leon, Florida on July 13th, 2010. Soybean rust was reported July 3rd in two counties in Alabama and one county in Florida. Rust has also been confirmed recently on soybeans in the northern portion of the state of Tamaulipas in Mexico. In 2010, soybean rust has been found in fourteen US counties and six states in Mexico.

NY State Soybean Rust Hotline: 607-255-7850

USDA Soybean Rust Website

Clipboard Checklist

Keith Waldron

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  • 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 any patches of herbicide resistant weeds, weed escapes
  • Storage areas cleaned and ready to accept hay, wheat harvest


  • Monitor fields for plant vigor, growth stage, R stage pest issues (corn rootworm, European corn borer, armyworm, foliar diseases, nutritional deficiencies)
  • Check no-till fields/fields with high residue or weeds for slug/snail damage
  • Monitor for weeds, note presence of "who", "how many" and "where"
  • Monitor tasseling corn fields for presence of corn rootworm beetles.

Small Grains:

  • Monitor spring grains for crop stage (heading, grain fill), insect problems and foliar / head diseases
  • Evaluate crop for plant vigor, lodging, maturity / time till harvest
  • Grain bins ready to accept upcoming harvest?

Alfalfa & Hay:

  • Monitor alfalfa seedings for weeds, insects & diseases.
  • Check regrowth of established alfalfa stands for potato leafhopper, weed and disease problems.
  • Storage areas cleaned and ready to accept incoming harvest


  • Evaluate stand growth, development and condition
  • Monitor fields for soybean aphid, foliar diseases, white mold, natural enemies, 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 water sources, drainage, roof gutters for leaks and potential overspill
  • Continue fly monitoring: install "3X5" index card fly speck monitoring cards through out barn
  • Install/refresh/replenish as needed: fly tapes, insecticide baits, natural enemies (parasitoids

Dairy Livestock Pasture Fly Management:

  • Monitor animals for presence of pasture fly pests. Treatment guidelines: Horn flies (50 per dairy animal side, 100 per side for beef cattle), face flies (10 per animal face), stable flies (10 per 4 legs). See our Livestock IPM homepage.
  • Consider installing biting fly traps to reduce horse, deer and stable fly populations.


  • Check storage areas (bunk silos, etc.) for readiness to accept upcoming wheat harvest
  • Clean in and outside of storage bins and grain handling equipment
  • Keep areas around storage bins and silos clean and mowed
  • Check areas around storage bins and silos for vertebrate tunneling
  • Check temperature of recently baled hay in hay mow


  • Note any repairs needed for recently used equipment: tractors, tillage implements, planters, sprayers, etc. as they are cleaned and serviced.
  • Service hay harvesting equipment as needed.
  • Calibrate manure spreaders - maintain records on amount spread per field


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.

Contact Information

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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