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NY Weekly Field Crop Pest Report, 2005

August 26, 2005 Volume 4 Number 19

1. View from the Field

2. Stop! Check for Corn Ear Rot

3. Think Weeds in the Fall!

4. Keeping Pest Records

5. Soybean Rust Update

6. Growing Degree Days in NYS

7. Clipboard Checklist

8. Contact Information

View from the Field

Western NYS

Julie Stavisky

Eastern NYS

Ken Wise

NYS

Keith Waldron

From the soybean TAg team in Orleans County, Nancy Glazier (NWNY Team) reports that pests are really winding down. Most beans are in the R-6 stage, indicating that maturity is approaching fast and actions for pest management are unlikely to provide an economic benefit. In the very northern areas of Orleans County, fields are still extremely dry and plagued by spider mites. Following up on diseases previously reported on by Nancy, downy mildew is still prevalent, and the Phytophthora outbreak reported on several weeks ago has not progressed to any serious extent. Soybean aphids are generally few and far between, with some of the small white forms of the aphids being observed (“white dwarves”). It is suspected that soybean aphids take on this appearance as nutritional value of the leaves declines during pod fill.

In Wyoming County, potato leafhopper numbers were low in Julie Hansen’s (Cornell Plant Breeding Department) alfalfa variety trial. In Cattaraugus County, Dean Sprague (CCE of Cattaraugus, Allegany, and Chautauqua Counties) and I noticed that grasshoppers were extremely abundant in a grass/clover hay field, but feeding damage was not severe.

This week while in Orange County we were in a field that had many problems. First was that the corn was drought stressed and had not received rain in weeks. The second issue was there was much damage to the corn by birds and deer (See picture).

File written by Adobe Photoshop® 4.0

This allows pathogens to enter the ear of corn and reduce yield and quality of the crop. Here is a picture of what can happen when the ears are opened by a vertebrate pest.

File written by Adobe Photoshop® 4.0

This is a picture of common smut attacking an ear of corn and part of the stalk. For more information on corn ear diseases please refer to the next article.

Two spotted spider (TSM) mite injury evident on many drought stressed soybean fields. First indication of a problem is often the appearance of chlorotic, stunted plants on the field margin. Close inspection of individual plants shows leaves with a stippling of fine yellow dots on the upper surface and presence of small mites with two spots on the underside of leaves. Mites tend to congregate in the leaf vein areas. A webbing under the leaves can accompany higher TSM populations. Field symptoms extend interior from margins into the field in a "V" shaped pattern, the smallest point of the "V" going into the field. From this infestation spider mites use their ability to create a fine web strand as a means to "balloon" into the field riding the prevailing winds. This new infestation develops over time into a circular area of chlorotic, stunted plants. A patchy, spotty chlorotic appearance to fields may warrant inspection for spider mite damage.

Stop! Check for Corn Ear Rot

Ken Wise, NYS IPM

Are you ready with the chopper or combine? STOP; check for corn ear rots first! Some kinds of fungi can create mycotoxins that are toxic to livestock. Taking a few minutes to check a field for certain ear rots can help you determine if you want to feed your field of corn to livestock. Pull back the husks on several plants and look for the presence mold growing on the ear of corn. The following are specific symptoms of certain ear rot diseases that can be found in NYS:

Fusarium Ear Rot appears as a white-to-pink or salmon-colored mold. This mold can begin with bird, deer or insect-damaged kernels. Fusarium ear rot may contain fumonisins which are mycotoxins that can be toxic to livestock.

Gibberella Ear Rot symptoms are pink to reddish colored mold. This disease starts near the tip of the ear and progresses down toward base of the ear. Gibberella can produce vomitoxin and zearalenone which is toxic to many kinds of livestock.

Diplodia Ear Rot symptoms appear as a thick white mold that usually starts near the base of the ear. This disease can also appear on the plant as raised black fruiting bodies on moldy husks or kernels. Diplodia does not produce any known toxins.

Cladosporium Ear and Kernel Rot symptoms appear as greenish black, blotched or streaked kernels scattered over the ear. This disease can also infect kernels that have been damaged by insects, birds, deer, hail, or frost. The disease can progress after the grain is harvested and stored.

Penicillium ear rot or blue eye symptoms range from a powder-like green or blue-green mold that is on and between the kernels and normally on the tip of the ear. If this disease progresses in storage it is referred to as blue eye because the germ is a bluish-green color. Penicillium ear rot can produce a mycotoxin called “ochratoxin”.

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

Resistant Crop Clean Plow

Corn Disease Variety Rotation Down of Residues Fungicides

Ear Rots 2 2 2 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

While there isn't any practical solution for coping with ear rots this late in the current season proper fertilization, timely weed control and reductions in insect pest pressure can help reduce risk of disease. For example: European corn borer (ECB) resistant Bt corn is at lower risk for injury by this insect. Lower risk means fewer ECB tunnels into stalks and less potential for fungi to infect through wounds and cause stalk rot. Also avoid continuous planting of corn under conservation tillage where stalk rot can be prevalent. If you are harvesting corn grain make sure you clean the grain bins. Keeping the proper temperature, moisture content and good aeration in the grain bin can reduce storage molds from developing. It is important to have regular inspections of the stored grain. This is essential to minimize risk of developing insect and mold associated storage problems. Harvest silage at recommended maturity and moisture level, and pack silage tightly and exclude air rapidly. Consider using organic acid preservatives if you can't exclude air or reduce moisture. If you had a lot of stalk rot and were growing for grain consider chopping earlier for silage to minimize lodging and combine losses. There are kits you can purchase to test your corn for different toxins on your own farm. The following are places where you can also test your corn:

Dairy One Forage Lab in Ithaca: For more information, call the lab at 1-800-496-3344 extension 172.

The Cornell College of Veterinary Medicine's Nutritional and Environmental Analytical Services Lab: More information is available on the web (www.vet.cornell.edu/public/neas/) or from lab manager Joe Hillebrandt at 607-257-2345

Think Weeds in the Fall!

Ken Wise, NYS IPM

In the fall, weeds 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 encourage growers to look at their fields---it will help save on weed control costs and increase crop production. Remember, if you don't look, you will never know. For more information on weeds in corn checkout our online publication: Weeds in Field Corn

Keeping Pest Records

Ken Wise, NYS IPM

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, 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…

Soybean Rust Update

Keith Waldron, NYS IPM

From: http://www.ppath.cornell.edu/soybeanrustny/default.htm

2005 Asian Soybean Rust Status

Soybean rust was most recently confirmed in southern South Carolina and central Georgia. This is the first report from South Carolina in 2005. These are currently the most northern reports of soybean rust in the U.S. To date, positive confirmation of soybean rust has been reported in Alabama, Florida, Georgia, Mississippi and South Carolina. Scouting and spore trapping continues throughout the soybean production areas of the U.S. Scouting of sentinel plots in New York State continues this week and to date no soybean rust has been found. The risk of soybean rust infection in New York is currently considered to be low and no fungicide application for soybean rust is advocated at this time. Growth stages in New York State sentinel plots range from R5 to R6. (Last updated 8/17/05)

Growing Degree Days in NYS

March 1 - August 25, 2005

Location

Base 50 F

Batavia

1859*

Chazy

1766

Clifton Park

2420

Geneva

1987

Ithaca

1897

Prattsburg

1823*

*missing data

Source: http://newa.nysaes.cornell.edu/

Clipboard Checklist

Keith Waldron, NYS IPM

General:

• Maintain crop production activity records by field, including harvest date, pesticides used, nutrient inputs including manure, etc.

• Check fall harvest equipment, sharpen chopper knives, check shear clearances, check protective shields on all harvest machinery

• Check bunkers and silos. Prepare for corn silage.

• Mow weeds around barn, grain storage bins, farm buildings, pastures, control weeds, brambles.

Alfalfa & Hay:

• Continue monitoring for potato leafhopper -harvest early or spray on basis of need.

- HALVE PLH thresholds for fields under drought stress…..

• Monitor fields for weeds and diseases: record information on type and location for future cropping decisions.

• Harvest third cutting of alfalfa about 40 days after second harvest.

• Record hay yields by field and quality by storage facility; take samples for forage analysis

Field Corn:

• Monitor corn rootworm adults at silking.

• Observe corn for weeds, stalk rots / lodging, and nutrient and moisture deficiencies

Soybeans:

• Monitor for soybean aphid (SBA), soybean rust, pod, stem and foliar diseases. When checking for SBA, look for winged forms as an indication that the population may soon leave the field.

Livestock:

• Continue manure management and release of biological control agents (parasitic wasps) for house fly and stable fly control.

• Monitor young stock for cattle lice and mange mites

• Check condition of pastures and animals on pastures:

- Evaluate need for face fly, horn fly, and stable fly control measures

Contact Information

Julie Stavisky: IPM Area Educator, Livestock and Field Crops, Western NY
Phone: (315) 331-8415
Fax: (315) 331-8411
Email: js38@cornell.edu

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