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Weekly Field Crops Pest Report 2008

July 21, 2008                 Volume 7 Number 14

1. View from the Field

2. Weather Outlook 7-17-08

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

4. Stable flies affecting animals on pasture

5. European Corn Borer Opens the Door for Anthracnose Stalk Rot

6. Soybean Rust Update

7. Soybean Aphid Update

8. Clipboard Checklist

9. Upcoming Meetings

10. Contact Information

View from the Field

Ken Wise

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Potato leafhopper (PLH) populations were OVER threshold in 18-20 inch alfalfa at the Cornell Research Farm at Valatie. PLH numbers were at 420 PLHs in 3 samples. This field had turned yellow and shows the classic signs of PLH burn. This infestation level is over 5.5 times the economic threshold for that height alfalfa. Most of the PLHs this week were nymphs. Mike Hunter reports PLHs were wide spread throughout the southern part of Jefferson County. Keep a watchful eye on PLH populations this time of year. They can be brought in with weather fronts and once here…, they can increase in numbers very quickly as we continue to have hot weather.

Patricia Westenbroek in Sullivan County reports a very high infestation level of European corn borer in some field corn trial plots. For more information on European corn borer see the article below. Joe Lawrence (Lewis County) and Mike Hunter (Jefferson County) report some local corn fields over threshold for armyworm. These corn fields were sprayed to control this pest. Armyworm was also found in some grass and alfalfa mixed fields that were harvested early and not sprayed.

Weather Outlook 7-17-08

Art DeGaetano
Northeast Regional Climate Center

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Temperatures averaged about normal last week, particularly in western NY, with southeastern parts of the state as much as 3 degrees above normal. Most of the state also saw abundant precipitation, with a swath of 1-2 inch totals across a broad area of central NY. Less than 0.5 inches was observed however along the Lake shores in the Lower Hudson Valley and in the city and Long Island. Evaporative demand was also quite high, exceeding 1 inch across the entire state.

Nearly 150 base 50 GDD accumulated across most of the state. Seasonal totals now run from 1500 in the extreme southern Hudson Valley to 1100 from Albany through Syracuse, Rochester and Buffalo. Parts of the Adirondack, Catskill and Alleghany mountains have seen less than 1000 base 50 GDD. These seasonal totals are as much as a half week behind last year in extreme SW NY and about at last years levels in the east. Compared to normal the state is between 0.5 and 1 week ahead of the typical GDD accumulation.

A warm end to the week with highs in the low 90 and lows in the upper 60s across upstate will become showery as the weekend progresses. A low pressure wave will move along a stationary front stalled across northern Pennsylvania and move across NY Sunday into Tuesday giving us another round of showers and thunderstorms. Temperature will average above normal through Monday with highs in the mid-upper 80s and lows in the low to mid 60s. Temperature will briefly return to near normal on Wednesday and Thursday (low 80s and upper 50s), before climbing back to slightly above normal levels in the week 2 period as a ridge to our west strengthens. This should also keep the area somewhat drier than over the last couple of weeks.

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.

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 see the TAg Educational Materials.

Stable flies affecting animals on pasture

Keith Waldron

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Are your livestock animals stomping their legs to dislodge flies on their lower legs or belly? Are you getting bit around your ankles by an aggressive fly, about the size of a house fly? These biting flies are probably stable flies. The stable fly, Stomoxys calcitrans, is about the size of a house fly but is dark gray. Its abdomen has seven rounded dark spots on the upper surface. Similar in appearance to the common house fly, stable flies have a very prominent “spear-like” biting mouth part that extends forward from under the head. Both male and female stable flies feed on blood several times each day, taking one or two drops at each meal. Stomping of feet is a good indication that stable flies are present, since they normally attack legs and bellies. Production performance declines in infested herds because of the flies’ painful biting activity and animal fatigue from trying to dislodge flies. For more information see Integrated Management of Flies in and around Dairy and Livestock Barns.

Stable fly populations have been on the increase in many areas across the state. Considered a key fly pest of animals in confinement areas, these flies are becoming more of a pest for animals on pasture as well. Stable flies can breed locally in moist organic material such as spilled animal feed, the moist soil with round bale interface, spilled feed around feed bunks, poorly managed compost areas and water weeds washed to lake shorelines. Stable flies can also be transported long distances on weather fronts.

Stable flies are monitored by counting flies on all four legs of about 15 animals in the herd. Treatment is warranted when counts reach an average of 10 flies per animal.

Management requires removal of local conditions that favor fly breeding – i.e. reduce situations that favor accumulation of undisturbed moist organic matter. This option is, of course, not always doable or practical. Efforts are underway to evaluate various fly catching traps to help manage this pest by knocking down populations of locally breeding flies. One trap that has shown to have promise is constructed of clear alsynite (a fiberglass-like material) cylinder. Alsynite is attractive to these biting flies. When outfitted with a clear sticky surface, alsynite traps have been quite effective at capturing stable flies. At least two stable fly traps are available commercially. Two possible sources among others are Olson Products Biting Fly Trap (alsynite) and Farnam's Equine Products (non-alsynite but attracts via another method).

European Corn Borer Opens the Door for Anthracnose Stalk Rot

Ken Wise

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High infestation levels of European corn borer were reported in Sullivan County this week. Typical signs are broken leaf midribs, frass in the whorls, shot holes in leaves and holes in the stalks. European corn borer damage can on occasion cause localized problems for field corn producers. However, while its damage may be conspicuous, it more typically does not cause significant economic losses in NYS. If a field has had a history of ECB problems producers might consider crop rotation or the use of an ECB resistant (Bt) hybrid. In addition to direct feeding damage, the holes bored by ECB larvae can provide a means for the anthracnose fungus to enter the plant. Conditions that favor anthracnose stalk rot are continuous corn, surface corn residue (minimum & no tillage) and wet, humid, warm weather. Anthracnose stalk rot symptoms may appear after tasselling. Look for vertical, tan to reddish brown, water-soaked lesions (streaks) in the rind. Lesions become large, dark brown to shiny black. The best management practices to minimize or avoid anthracnose require action before or at the time of planting, i.e. the use of diseases resistant hybrids and hybrids with a good standability rating. Crop rotation with non-grass crops and plowing under infected residue are also recommended. Fields with high amounts of anthracnose leaf blight should be checked for indications of anthracnose stalk rot. If stalk rot is found you may wish to target that field for early harvest to avoid losses associated with premature lodging. For more information on corn diseases checkout see the TAg Educational Materials.

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. Over the last week, scouting has begun in these and plant growth stages in these plots range from V-1 to R-1. We will continue to provide foliar disease updates on these plots as the growing season progresses.

Recent detections of soybean rust in the Southeastern U.S. include two new counties in Florida and the first report of rust in Georgia in 2008. Since the beginning of 2008, soybean rust has been reported on kudzu in one county in Alabama; one county in Georgia, thirteen 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; one county in Mississippi, and three 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 July 17, 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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No soybean aphid issues have been detected in NY so far this season.

Crop Growth Stage - V-1 to R-1

Variations in planting dates have soybean growth stages ranging from early vegetative (V2-V4 to R1, some fields in western NY just beginning to enter R2 stage). Soybean heights also vary from 12 inches to nearly 30 inches tall.

Observation and Outlook - Insect

Soybean aphids (SBA) were first observed in sentinel sites week of June 26 (V3 stage soybeans in western NY).

Currently (July 18), SBA's are present in many (but not all) locations reporting from across the state, but remain at very low numbers, generally averaging 0 to less than 5 SBA's per plant. Occasional individual plants may have higher numbers. All fields reporting well below threshold. Natural enemy populations, such as lady bird beetles, are present and increasing in many areas.

Scouting and Management - Growers are encouraged to monitor for presence of soybean aphids, other insects and diseases. Fields entering the blooming stages should be monitored closely for SBAs, foliar diseases and white mold.

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, yields, etc.

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

Field Corn:

* Check crop growth stage and condition

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

* Tasselling / Pollinating corn check corn rootworm populations

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

* Check herbicide resistant corn fields for herbicide resistant soybean

* Adjust post emergence weed control actions

Small Grains:

* Evaluate crop for timing grain and straw harvest

* Storage areas cleaned and ready to accept next harvest?

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?


* Check 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

* Order fly management materials: fly tapes, insecticide baits, natural enemies (parasitoids)

* 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.

* 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 bins before adding newly harvested wheat.

* 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

Upcoming Meetings

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Aurora Field Day
Wednesday, July 23, 2008
Robert B. Musgrave Research Farm
Aurora, NY ( Poplar Ridge Road, Connects 90 and 34B)

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