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Weekly Field Crops Pest Report 2008

August 28, 2008                 Volume 7 Number 19

1. View from the Field

2. Weather Outlook 8.28.08

3. Alfalfa Snout Beetle in Fall Alfalfa

4. Soybean Rust Update

5. Soybean Aphid Update

6. Clipboard Checklist

7. Contact Information

View from the Field

Ken Wise

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Field crop extension personnel across NY have seen corn rootworm adults in the corn fields, fortunately, most observed fields have been below threshold. Japanese beetles have also been reported feeding on corn in fields across NY.  Brain Aldrich (Cayuga County) reports white mold in several soybeans fields. Ken Wise reports European corn borer damage in non-BT corn in a variety trial in Sullivan County. At a recent grower meeting in Sullivan county, Ken also learned of houseflies reaching high infestation levels in many dairy barns. This time of year livestock barns can have increased fly presence as flies seek warmer conditions to avoid cooler evening temperatures.

Weather Outlook 8.28.08

Art Degaetano
Climate Center, Cornell University

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Temperatures ran about 3 degrees below normal across the state, with the extreme western area running very close to normal.  Conditions were dry for a change last week with less than 0.5 inches of rain at almost all NY stations and many locations seeing no rain.  An additional 100-125 base 50 growing degree days accumulated over most of the state.  The extreme lower Hudson Valley and Long Island saw as many as 150 GDD.  Seasonal totals are now between 1800 and 2000 across all but the highest elevations of upstate NY.  Between 2200 and 2400 GDD cover the Lower Hudson Valley and Long Island.  These totals are running about a week behind last year’s accumulation in the west and about a half week ahead of last year in the Albany area.  Over much of the state the 2008 GDD accumulations are very close to the long term normal.

Some of the moisture from ex-tropical storm Fay and a cold front will bring a slight chance of showers across New York through early Saturday with the best chance for rain Friday night.  Amounts should be less than 0.25 inches.  High pressure will dominate the weather from Saturday through Wednesday with very little chance of precipitation. Temperatures will be a few degrees above normal with highs in the upper 70 to low 80s and overnight temperatures in the mid 50s to low 60s.  Beyond next Wednesday warmer than normal weather should persist as a ridge establishes itself just to our west.  Precipitation during this period is a tough call. It is unclear when and if the remnants of soon-to-be hurricane Gustov and another tropical system now in the Atlantic will affect NY.

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 ½ 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.

Soybean Rust Update

Gary Bergstrom
Plant Pathology, Cornell University

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Sentinel plots in New York State have been established in the following counties: Cayuga, Chautauqua, Chemung, Columbia, Cortland, Jefferson, Lewis, Madison, Niagara, Oneida, Ontario, Schoharie, Seneca, Steuben, Wayne and Yates. Plant growth stages in these plots range from R-2 to R-6. Mid to high levels of Septoria brown spot and downy mildew were detected in several of the sentinel plots across NYS last week.

Soybean rust has been detected in two new states over the past week. On August 22nd, soybean rust was detected on soybean in a research plot in Decatur, Georgia. On August 24th, soybean rust was reported in a commercial field at the R8 growth stage in Willacy County, Texas.

Since the beginning of 2008, soybean rust has been reported on kudzu in two counties in Alabama; four counties in Georgia, eighteen counties in Florida (two of these counties had reports on coral bean and snap bean and one had a report on soybean); three counties in Louisiana; three counties in Mississippi, and five counties in Texas. Reported infected kudzu sites in many counties have been destroyed. Rust was also reported in three states (5 municipalities) in Mexico on yam bean and soybean. These too have been destroyed or are no longer active. (Updated August 26, 2008 )

NY State Soybean Rust Hotline: 607-255-7850

NYS Soybean Rust Website

USDA Soybean Rust Website

Soybean Aphid Update

Keith Waldron

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Soybean aphid (SBA) populations remained low again this week across areas reporting in NY. Fields monitored are generally averaging 0 to less than 5 SBA's per plant at this time. All fields reporting were well below threshold. Natural enemy populations, such as ladybird beetles, are present in most areas.

Crop Growth Stage –

Soybeans generally in mid to later reproductive stages. Soybean heights vary from 16 inches to 30 plus inches tall.

Soybean aphid scouting and management – the low numbers of aphids being reported across NY continue to support close inspection of fields as a source of objective information on which to base potential insecticide use decisions. Risk of SBA damage to yields decreases as plants mature.

Nationally soybean aphid populations are currently of concern in Wisconsin, Minnesota, North Dakota, South Dakota, N. E. Nebraska, northern Iowa and Illinois. In some areas fields have received two treatments. By contrast soybean aphid numbers remain low in New York, Ohio, Indiana, much of Michigan and the southern half of Illinois.

Growers are encouraged to monitor for presence of soybean aphids, other insects and diseases. Fields in reproductive stages should be monitored closely for SBAs, foliar diseases and white mold.

Growers should evaluate need for soybean aphid management based on a field visit and SBA population assessment. The national soybean aphid management recommendations, including the recommended soybean aphid action threshold for R1 (beginning bloom) through R8  (full maturity) reproductive stage soybeans are:

R1 to R5 growth stages

- During the period when the soybean crop is reproductive (i.e. flowering) in the R1 to R5 growth stages, an insecticide application may be necessary when 250 or more aphids occur per plant and approximately 80% of the field is infested and populations are increasing. Sequential scouting in the same field is necessary in order to determine if populations are increasing. Comparing SBA counts over a week or more is necessary.

R6 growth stage (full seed size in top 4 nodes)

A higher threshold is required for economic return during the R6 growth stage, but no threshold data is available at this time. If treatment options are considered, ensure pre-harvest intervals of the insecticidal product chosen are met prior to application.

R7 growth stage and later (beginning maturity to full maturity).

During the R7 and R8 growth stages, there is no economic return on insecticidal applications.

For more information see: USDA Public PIPE Website: Management Toolbox - Guidelines - USA

Clipboard Checklist

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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, yields, etc.

* Watch for weed escapes, any patches of herbicide resistant weeds?

* Prepare bunkers, silos for incoming silage. * Mow around storage bins, barn and farm facilities

Alfalfa & Hay:

* Monitor alfalfa seedings for weeds, for potato leafhopper & diseases.

* Check established alfalfa stands for potato leafhopper, weed encroachment and disease problems.

* Storage areas cleaned and ready to accept next harvest?

Small Grains:

Check grain storage bins for temp, moisture, air flow, drying conditions.

* Prepare for planting winter wheat after Hessian Fly-free date

Field Corn:

* Note crop growth stage and condition

* Check for European corn borer, armyworm, foliar and stalk rot diseases, vertebrate injury (birds / deer), weed escapes, herbicide injury, nutritional deficiencies, etc.

* Check corn for grain fill issues – mold, insects, vertebrate damage

* Monitor weed populations noting presence of "who", "how many" and "where"

* Harvest corn silage at 65 to 68% moisture and high moisture shelled at 25 to 30% grain, and high moisture ground-ear at 30 to 35% moisture.

* Record corn silage yields by field and quality by storage area, take samples for forage analysis

* Take Soil Samples for fertility analysis

* Take Fall Weed Survey following harvest.


* Note crop growth stage and condition

* Evaluate stand for soybean aphid, spider mites, deer, weed assessment, foliar disease incidence

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


* Provide annual maintenance to manure, fertilizer, and pesticide application equipment * Prepare combines for corn, soybeans * Sharpen chopper knives. Check shear clearances, protective shields * Note any repairs to harvesting equipment as they are cleaned and lubricated.

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