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Weekly Field Crops Pest Report 2010

September 3, 2010            Volume 9 Number 18

1. View from the Field

2. Weather Outlook

3. Alfalfa Snout Beetle in Fall Alfalfa

4. Think Weeds in the Fall!

5. Keeping Pest Records

6. Clipboard Checklist

7. Contact Information

View from the Field

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Last week, I discovered what looked like gray leaf spot in a field of corn at the Cornell Research Farm in Valatie. The infestation is quite severe. Gary Bergstrom and Katie Waxman confirmed that the samples we sent had gray leaf spot and northern corn leaf blight. There were also lesions on the sheath which they state most likely are saprophytic. Many of the ears of corn are showing bird and deer damage. This opens the ear of corn to several pathogens. I had an article in last week’s pest report on corn ear rots.  For more information on corn ear rots please see the Pest Report for August 27, 2010, article Stop! Check for Corn Ear Rot!

Saprophytic lesions on corn

Bird damage to corn 

Weather Outlook, 9-2-10

Jessica Rennells
NOAA Northeast Regional Climate Center, Cornell University

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Last week temperatures ranged from 3 to 6 degrees above normal.  Precipitation ranged from .01 to half an inch for most of the state.

The base 50 Growing Degree Days ranged from less than 100 to 150.  Almost the entire state is ahead of last year by over three weeks.  Compared to normal, most of the state is ahead by over three weeks.

We will have cooler temperatures and chances of rain, but will end the week with sunny skies and warm temperatures.

Today‘s highs will be in the upper 80’s and low 90’s.  Tonight’s temperatures will be in the upper 50’s and 60’s.

Friday will be cooler in the mid 70’s to mid 80’s.  Friday night will be mid 50’s to low 60’s.  Showers and thunderstorms are possible as a cold front passes through.

Saturday’s highs will be in the mid 60’s to low 70s with rain likely.  Sat will also be windy with some gusts likely, are only affects from Hurricane Earl.  Lows will be in the upper 50’s and low 60’s.

Sunday highs will still be in the mid 60’s to low 70’s with continued rain, but most likely for northern NY.  Overnight temperatures will be in the upper 40’s and low 50’s.

Monday will be sunny with highs in the low to mid 70’s.    Lows will be in the upper 40’s and low 50’s.

Tuesday’s temperatures will be in the mid to upper 70’s.  Lows will be in the low to mid 50’s.

Wednesday’s highs will be in the mid to upper 70’s with lows in the upper 50’s and low 60’s.

The five day precipitation amounts will be a tenth to a quarter of an inch.   The 8-14 day outlook is showing above normal temperatures and neither above nor below normal precipitation. 

Alfalfa Snout Beetle in Fall Alfalfa

Keith Waldron

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Short, chlorotic alfalfa? Alfalfa stands showing signs of premature senescence? Do you grow alfalfa in Oswego, Jefferson, Cayuga, Wayne, Lewis, St. Lawrence, Clinton, Essex or Franklin Counties?

If your farm is located in one of the above NY counties where ASB has been confirmed… watch your alfalfa fields this fall for signs of stress as this is when fields can begin to show symptoms of ASB larval feeding damage. Alfalfa snout beetles (ASB) are root-feeding weevils.  The vast majority of ASB impacts come from direct root loss and plant death caused by ASB larval feeding. ASB feeding damage may be suspected if one detects alfalfa fields with short, chlorotic, or otherwise weakened plants or large areas within fields void of any alfalfa.

In North America these insects are only found only in the nine northern New York counties listed above and in portions of southern Ontario, Canada.  The native home of snout beetle is Europe where it can be found from Italy to England and Poland.

Alfalfa snout beetle larvae are legless, white, and ∏ inch long. ASB larvae are found shallow in the soil when very small but move deep in the soil during mid July to late August (18-24 inches). In September the large larvae move back up to the top 8 “ and do most of the tap root severing in September and October.  After development is completed, they then move deep in the soil to overwinter. Larvae move deep in the soil in the fall after feeding (18-24”) and remain there for the next 18 months.  Midway through the summer they pupate but remain deep in the soil until the following spring.

If you grow alfalfa in one of the counties mentioned and suspect ASB injury, dig up a few plants showing symptoms getting as much of the root system as possible. Look for damaged, girdled roots and presence of ASB larvae.

ASB damage in the spring looks similar to winter killed alfalfa with plants failing to “green up”.

Plant breeding and biological control research is underway at Cornell to develop options to mitigate ASB injury. But for now the best option for managing this important pest is a three year crop rotation with a row crop.

Fall stand counts are an indication of the health of your alfalfa crop. There are a number of pests and crop management issues that can reduce a stand count in alfalfa. The following are guidelines for stand counts in NYS:

Crowns per square foot
Harvest Year
Optimum Stand
Adequate Stand
New Spring Seeding
1st hay year
2nd hay year
3rd and older

Fall scouting before the first hard frost can also reveal pest problems. If you find yellow to brown plants it may indicate one of several different disease problems. These could range from disease problems such as verticillum wilt, leaf spots, fusarium wilt, anthracnose and more. An inspection of the root system can also indicate disease problems. Yellow, reddish-brown to black discolored or damaged roots may indicate presence of phytopthora root rot or verticillium wilt. Premature senescence of alfalfa stands may indicate stress damage by alfalfa snout beetle larvae in those counties with confirmed infestations.

More information on current alfalfa snout beetle management projects using nematodes as biological control agents and efforts to develop resistant alfalfa varieties can be found at the Northern New York Agricultural Development website.

Think Weeds in the Fall!

Ken Wise

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In the fall, many weed species are fully-grown and easily identified. Correctly identifying and recording significant weed infestations and their location is helpful for improving weed management decisions. Knowing the weed type and biology (broadleaf, grass, sedge, summer or winter annual, biennial, or perennial) is critical in selecting the right weed control measures. Remember, while herbicides are widely used for weed control other methods like crop rotation, cultivation, proper fertilization, planting dates, banding pre-emergence herbicides, crop spacing, plant populations, cover crops and combinations of these techniques should also be considered as part of an integrated weed control program. Conduct your fall weed surveys from late August through October. Sketch out a map of the field, walk each 1/4 of the field, and record the identity and relative infestation of the significant populations of weeds you observe. While no economic thresholds have been developed for weeds in New York, we recommend using a weed rating scale. The following scale can help you determine the severity of weed infestations in cornfields.

Evaluating Weed Presence- Weed Rating Scale: Determine the intensity of each weed species as follows:

None: No weeds present

Few: Weeds present but very few plants within the field. Enough plants to produce seed but not enough to cause significant economic loss in the current year.

Common: Plants dispersed throughout the field, an average of no more than 1 plant per 3 feet (.91m) of row, or scattered spots of moderate infestation.

Abundant: Fairly uniform concentrations across field. Average concentrations of no more than 1 plant per foot (.30m) of row or scattered spots of severe infestations.

Extreme: More than 1 plant per foot (.30m) of row for broadleaf weeds and 3 plants per foot of row for grasses, or large areas of severe infestations.

So take a few minutes and look at your fields---it will help save on weed control costs and increase crop production. Remember, if you don't look, you will never know what weeds are there.

Keeping Pest Records

Ken Wise

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It is very important to keep records from year to year on certain pest problems that may have occurred. Write down observations that you made over the season. Did potato leafhoppers go over threshold and which field(s)? Were there certain corn diseases present? Did you have corn that had corn rootworm injury? Were there new weeds or weed escapes you did not expect this year? Pick up a pencil and write them down on a field to field basis to better select certain management practices the next season. For example, if you were hit with potato leafhoppers this season and you want to rotate your alfalfa, one management option to consider for the future is use of a potato leafhopper resistant alfalfa variety. Another example might be to select wheat varieties that are resistant to certain diseases. If you had weed escapes you might reconsider your selection of weed control products. Are your pesticide use records up to date? Rates, dates, efficacy, rotational restrictions, etc. It is always important to keep pesticide records up to date.  If you wait too long you may forget what happened in certain fields. So write them down! A sharp pencil beats a dull memory… 

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

Field Corn:

  • Note crop growth stage and condition
  • Check for European corn borer, armyworm, foliar diseases, vertebrate injury (birds / deer), weed escapes, herbicide injury, nutritional deficiencies, etc.
  • Check tasselling / pollinating corn for corn rootworm populations
  • Monitor weed populations noting presence of "who", "how many" and "where"
  • Check herbicide resistant corn fields for herbicide resistant soybean

Alfalfa & Hay:

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


  • Note crop growth stage and condition
  • Evaluate stand for soybean aphid, spider mites, deer, weed assessment, foliar disease incidence
  • Check herbicide resistant soybean fields for herbicide resistant corn

Dairy Cattle: Livestock Barn Fly Management:

  • Monitor animals and facilities for house fly and stable fly populations
  • Check facilities for favorable fly breeding conditions: (organic matter + moisture): leaks in watering systems, roof gutters for leaks and potential overspill, drainage,
  • 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
  • Continue fly monitoring: install "3X5" index card fly speck monitoring cards through out barn
  • Use, replenish, replace fly management materials: sticky fly tapes/ribbons, insecticide baits, natural enemies (parasitoids), fly population monitoring (3 x 5) spot cards
  • Continue release of purchased natural enemies (fly attacking parasitoids)

Dairy Cattle: Pasture Fly Management:

  • Monitor animals for presence of face flies, horn flies and stable flies. Action guidelines: face flies (average 10 per animal face), horn flies (average 50 / dairy, 200 / beef cattle per animal side), stable flies average 10 per animal  (all four legs)
  • Check feed bunk / water source locations for signs of stable fly breeding (moist undisturbed organic matter – spilled feed, round bales, etc.), minimize source of moist organic matter i.e. fly breeding areas in barn and in adjacent animal loafing yard
  • Check paddocks for forage quality / quantity, rotate as appropriate
  • Check paddocks for vegetation poisonous to livestock
  • Consider use of fly traps to help reduce deer, horse and stable fly populations


  • Pre-clean in and around grain storage bins in anticipation of soybean and grain corn harvests.
  • Keep areas around storage bins and silos clean and mowed


  • Note any repairs needed for recently used equipment: tractors, tillage implements, harvesting equipment, etc. as they are cleaned and serviced.
  • 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