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Weekly Field Crops Pest Report 2008

August 9, 2008                 Volume 7 Number 17

1. View from the Field

2. Weather Outlook 8.7.08

3. Certified seed and fungicide seed treatment are good insurance for winter wheat

4. Check For Stalk Rots!

5. Soybean Rust Update

6. Soybean aphid update

7. Clipboard Checklist

8. Contact Information

View from the Field

Ken Wise
NYS IPM

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Wet weather seems to be the biggest topic for discussion this week. Periodic thunderstorms and intermittent showers affecting hay harvest and other on-farm tasks. Crop growth in well drained areas, however, has generally been reported to be good.

Flies attacking dairy animals on pasture were the focus for a pasture fly meeting in Columbia County this week. The timing was perfect for in-field observations and a great discussion of the biology, thresholds and management of horn flies, face flies and stable flies on pasture. Both horn flies and face flies were over suggested action guidelines on the Angus herd viewed. Since eggs, larvae and pupal stages of horn flies and face flies live in the dung pats we dissected a few. (Sorry if you were not there to participate in that experience.) We found some fly larvae and pupae along with a lot of dung beetles.  We discussed the importance of dung beetles in breaking down cattle manure in pastures, in the process disrupting the life cycle of those flies by destroying their larval development habitat. Dung beetles compete with other organisms like flies within the cattle pat for resources within the manure, thus limiting pasture fly development. There are three types of dung beetles in a cattle pat:

Rollers (telecoprids): Geotrupes species, form balls of manure which they push from the pat to bury as brood balls

Tunnelers (paracoprids): Onthophagus species are tunnelers that consume the pat and burrow beneath it to bury brood balls. 

Dwellers (endocoprids): Aphodius species, consume the manure as they tunnel within the dung pat and oviposit eggs in the manure or surrounding soil.  Most dung beetles found in NY are dweller types.

Potato leafhopper populations appear to remain at low numbers so far this season. Last Friday while conducting an IPM field meeting in Essex County we viewed the typical yellow v-shaped damage potato leafhopper can do to alfalfa. The population had fallen off but the signs of damage were there. During the same meeting we scouted a corn field for corn rootworm and found that it was over threshold. Most of the beetles in the field were the northern corn rootworm beetles.

Weather Outlook 8.7.08

Art DeGaetano
NOAA Northeast Regional Climate Center, Cornell University

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New York saw a fairly normal week temperature-wise with most stations within a degree (plus or minus) of normal.  Between 125-150 base 50 GDD accumulated across the state except in the higher elevations where the accumulations were as low as 100. Almost 200 GDD accumulated near New York City.  Seasonal GDD totals range from 2200 near New York to 1800 in the Hudson Valley and along the Lakes. Around 1500 GDD characterizes much of Central NY with seasonal totals as low as 1000 in the higher elevations.  These accumulations are slightly ahead of last years and about 3-7 days ahead of the normal.

Much of the state received between 1-2 inches of precipitation last week.  There was a swath of 0.5-1.0 that extended from near Syracuse across the Mohawk Valley and south through the Catskills. The lower Hudson Valley and City generally saw about an inch of rain.

High pressure will give way to yet another upper level low pressure system that will traverse the state on Friday and Saturday. With this system most places will see about 0.5 inches of rain with higher (closer to an inch) amount in the northern part of the state.  The low will weaken and move east late Saturday, bringing a period of dry weather until at least Wednesday or Thursday.  Temperature through the period will average slightly below normal, starting off about 5 degrees below normal but rebounding to a couple of degrees above normal by Wednesday.

Beyond next week a trough  pattern will continue in the east, with temperatures at or slightly below normal and several opportunities for precipitation.

Certified seed and fungicide seed treatment are good insurance for winter wheat

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Soilborne fungal disease occurrence on roots, stems, and crowns of winter wheat are generally not severe when wheat growers rotate with non-cereal crops. However, low levels of soilborne and seedborne fungal diseases can cause problems with stand establishment. A stand that is not well established in the fall will have a harder time making it through the winter, and may not be as quick to green up in the spring.

Seedling disease threats can largely be prevented with the use of fungicide-treated seed. These threats include the smut diseases that may be present on the surface of the seed or deep inside the embryo of the seed. Also, several soil-dwelling disease agents can cause plant roots and/or crowns to rot before the plant becomes established. In addition, seed fungicide treatments can aid in the suppression of early foliar diseases such as powdery mildew in the fall.

Fungicide-treated seed is widely available commercially, or treatments of fungicides can be made on-farm. The most effective treatments combine a systemic fungicide and a protectant fungicide. For specific reference to chemicals, please visit the Cornell Guide for Integrated Field Crop Management.

Another key tactic for good stand establishment is to plant certified seed. Use of certified seed assures a grower that seed meets high state and national standards for purity, identity, and freedom from noxious weed seeds and seedborne diseases.

Check For Stalk Rots!

Ken Wise
NYS IPM

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It is important to monitor your fields for stalk rots as you start thinking of your corn harvest. If you have an infection of stalk rot it can cause the plant to die early losing grain or silage yields. Stalk rots are caused by many different fungi that enter the plant. They occur when the plant is under stress or when it may be injured by insect pests, hail, deer and bird damages, drought or soil saturation, lack of sunlight, extended cool weather, and the lack of fertility. The following are symptoms of specific stalk rots:

Anthracnose stalk rot symptoms may appear after tasselling as vertical, tan to reddish brown, water-soaked lesions (streaks) in the stalk rind. Lesions become large, dark brown to shiny black. Fields with high amounts of anthracnose leaf blight (both diseases have the same causal agent) should be checked for indications of anthracnose stalk rot.

Diplodia stalk rot symptoms may appear as numerous black pycnidia in the lower internodes of the stalk. The black dots are the size of a pinhead or smaller. When conditions are wet a white mold may develop on the stalk surface.

Fusarium stalk rot normally starts just after pollination and symptoms appear later in the season. When you cut open the stalk, the pith appears as a whitish to pink (salmon) color. There are also distinctive brown streaks on the lower internodes.

The first symptom of gibberella stalk rot is the onset of grayish-green color of the leaves. The stalk will turn dark green to tan near the base of the plant. The pith of the stalk becomes soft and will appear as a red to pinkish color.

Pythium stalk rot normally appears as a decay of the first internode above the soil. The pith will become soft, turn brown and appear water-soaked. Many times the stalk can twist and/ or lodge. Even though it may have lodged the plant will stay green for several weeks because the vascular tissue is not destroyed.

If you discover certain stalk rot diseases make notes of the hybrid, tillage methods, rotation history, and planting date. By doing this you be able to avoid the disease occurrence in the future. The following is the effectiveness of specific management practices for stalk rots:

Corn Disease
(Stalk Rots)
Resistant Variety
Crop Rotation
Clean Plow
Down of Residue
Fungicides
Anthracnose
1
1
1
4
All Other
2
3
3
4
1= highly effective, 2= moderately effective, 3=slightly effective, 4= not effective, 5 = not usually economical,
Reference: Purdue University Field Crops Pest Management Manual

As with most diseases that attack corn, if you can reduce stress on the plants you most likely can reduce the occurrence of certain stalk rots. Having a sound fertility program based on soil testing is important for keeping a corn plant healthy. Select a hybrid with resistance to certain diseases and good standability that is adapted to your region. Some of these stalk rots can produce mycotoxins that can be toxic to livestock. You should consider having silage tested for certain mycotoxins if you had fields with stalk rots this season. For more information on corn diseases checkout our online publication, Corn Diseases in New York State.

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 V-2 to R-3. Low to mid-levels of downy mildew and Septoria brown spot were detected in several of the sentinel plots across NYS last week.

The most recent detection of soybean rust in the U.S. was on July 28, 2008 in soybean production fields in Cameron County, Texas.

Since the beginning of 2008, soybean rust has been reported on kudzu in two counties in Alabama; one county in Georgia, sixteen 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 four 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 5, 2008 )

Soybean aphid update

Keith Waldron
NYS IPM

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No soybean aphid issues have been reported in NY so far this season.

Crop Growth Stage - V-10 to R-4
Soybeans are in reproductive growth stages in most areas reporting. Soybean heights vary from 20 inches to 36 plus inches tall.

Observation and Outlook - Insect
Soybean aphid (SBA) populations remain low across areas reporting in NY. SBA's are present in many (but not all) locations reporting from across the state, generally averaging 0 to less than 5 SBA's per plant. Occasionally individual plants may have higher numbers. All fields reporting well below threshold. Natural enemy populations, such as ladybird beetles, are present and increasing in many areas. Field monitoring continues to be hampered by frequent storms.

The national soybean aphid commentary (7.28.08) mentions southern Minnesota fields are nearing or over threshold. The production and emigration of winged migrants from this area is likely. Possible impacts, if any, on soybean aphid populations in NY remains to be seen.

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.

While localized soybean aphid problems have occurred in recent years, the low numbers of aphids being reported across NY so far this season continues to support close inspection of fields as a source of objective information on which to base potential insecticide use decisions. There is no data to suggest that very low aphid populations hurt yield. Judicious treatments based on field monitoring optimize net profit, protect natural enemies from unnecessary insecticide use, and lessen risks that the soybean aphids would develop a resistance to insecticides.   If an insecticide is used, growers are advised to leave an untreated check for side by side treatment comparison.

As soybean fields enter their reproductive phase of development, growers should evaluate the need for the insecticide based on a soybean aphid population assessment. Fortunately, soybean aphid population assessment is fairly easy. The national soybean aphid management recommendations, including the recommended soybean aphid action threshold, follow.

National Soybean Aphid Management Guidelines
(Source: www.sbrusa.net.)

Emergence to Vegetative
During the period when the soybean crop is in the emergence to vegetative (not reproductive, i.e. no flowers) growth stages, current research data has shown that spraying will not result in an economic return. Although uncommon, soybean aphids have reached threshold during the vegetative stage in some regions.

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.
- The data scale chosen also potentially corresponds with input of speed scouting information. For more information on the University of Minnesota speed scouting program visit Soybean Aphid Sampling. The speed scouting protocol differs from the soybean aphid sentinel plot protocol, but collection of this mobile data is also possible.

- Always read, understand, and follow pesticide label recommendations.
- Please follow your state's insecticide guidelines for more information on pesticide use.
- Insecticide applications should only be considered when needed according to the pest population status.
- Tank mixing with fungicides is not recommended unless soybean aphids have reached threshold requirements mentioned above and spraying for soybean rust treatment is also recommended by your state extension plant pathologist.
- Unnecessary pesticide applications may increase pest problems by adversely affecting beneficial insect natural enemy populations.

R6 growth stage
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
During the R7 and R8 growth stages, there is no economic return on insecticidal applications.

(For more information see: Management Toolbox - Guidelines - USA)

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, 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.

* Pollinating corn - check corn rootworm populations, evidence of stalk rot

* 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

* Note any differences between Bt hybrids and non-Bt refuge portions of fields

Small Grains:

* Evaluate standing crop for timing grain and straw harvest, evidence of sprouting (wheat)

* Storage areas cleaned and ready to accept next harvest?

Alfalfa & Hay:

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

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

* Storage areas cleaned and ready to accept next harvest?

Soybeans:

* 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

Storage:

* Pre-clean in and around grain bins before adding newly harvested wheat.

* Keep areas around storage bins and silos clean and mowed

Equipment:

* 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

Contact Information

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Keith Waldron: NYS Livestock and Field Crops IPM Coordinator
Phone: (315) 787 - 2432
Fax: (315) 787-2360
Email: jkw5@cornell.edu

Ken Wise: Eastern NYS IPM Area Educator: Field Crops and Livestock
Phone: (518) 434-1690
Fax: (518) 426-3316
Email: klw24@cornell.edu