North Carolina Pest News, June 28 2013 (Field & Forage Crops)

NORTH CAROLINA COOPERATIVE EXTENSION SERVICE
North Carolina State University * College of Agriculture & Life Sciences
Dept. of Entomology * Box 7613 * Raleigh, NC 27695 * Ph: (919) 513-8189

NORTH  CAROLINA  PEST  NEWS
Stephen J. Toth, Jr., editor
Volume 28, Number 12, June 28, 2013

CAUTION: The information and recommendations in this newsletter are applicable to North Carolina and may not apply in other areas.

FIELD AND FORAGE CROPS

From: Jack Bacheler, Extension Entomologist

Cotton Aphids and Spider Mites Behaving

So far, cotton aphids and spider mites have not tipped their hands, as we have not received reports of economic levels of either pest through today. A number of folks have reported low levels of spider mites in many cotton fields.

Plant Bugs Arriving?

Out 2013 plant bugs scene could get interesting. We mentioned last week that plant bug levels on weedy host vegetation and on field corn seemed to on the high side for us so far this year. This week, several cotton fields in eastern and east-central North Carolina have or are being treated. A few of these fields had upper square retention rates in the 60% range, as opposed to the 90 to 100% retentions more commonly seen in North Carolina cotton fields at this time of year. If we get a return to hot drier weather and the rapid drying down of plant bug hosts, further movement into cotton in some areas can be expected.

If sweep numbers are just at the threshold of 8 per 100 sweeps or perhaps at or less than 12 per 100, a chloronicotinoid like Centric (4.3 out of 5 rating -

http://ipm.ncsu.edu/cotton/insectcorner/PDF/Insecticide.Performance.Survey.2013.pdf) might be worth considering. The heavy hitters like acephate (4.5 out of 5 rating) and Bidrin (5.0) are slightly more effective than the most active nicotinoid for plant bugs, but also more disruptive, sometimes resulting in the establishment of later cotton aphid or spider mite outbreaks. With Bidrin, be careful of this product’s high mammalian toxicity and its 6-day field reentry interval. If a nicotinoid is used, be sure to come back with another chemical class if a subsequent application is needed (see Dominic Reisig’s blog of last week – http://www.nccrops.com/2013/06/22/insecticides-for-plant-bugs/). In addition to the list of plant bug products listed in the North Carolina Agricultural Chemicals Manual, Transform (4.5) now has a federal label for plant bugs. This product offers plant bug effectiveness in the range of acephate, but should be less disruptive on beneficial insects. The cost of this new product will likely be in the range of $10-11 per acre for most producers.

It’ll be interesting to find out how the plant bug situation develops during the next few weeks.  Remember that stink bugs cannot cause economic damage to pre-blooming cotton.

Cotton and Soybean Insect Scouting Schools Being Scheduled


Dominic Reisig, Extension Entomologist, and I are beginning to schedule our annual soybean/cotton scouting “schools”. Each school will cover both cotton and soybean insect ID, biology, crop damage, scouting procedures and the use of correct thresholds. Preliminary information will be reported on below dates:
July 15: Onslow County area
July 16: Greene County area
July 18: Bertie County area
July 17 or 19: Northampton and Halifax (separate schools)

From: Steve Koenning, Extension Plant Pathologist

Ascochyta Leaf Spot on Cotton

The Plant Disease and Insect Clinic (http://www.cals.ncsu.edu/plantpath/extension/clinic/) at North Carolina State University received a cotton sample on June 27, 2013 thought to have target spot caused by Corynespora. Ascochyta spp. was the only fungus found. This does not warrant fungicide applications. This is a fungus common in wet, relatively cool weather and does not impact cotton yield unless it infects the stem. Stem infection is not likely at this time. More information on wet weather blight (Ascochyta leaf spot) can be found at: http://www.ces.ncsu.edu/depts/pp/notes/Cotton/cdin2/cdin2.htm

From: Barbara Shew, Extension Plant Pathologist

Peanut Disease Advisories Will Start Soon

Peanut growers will begin foliar disease control programs soon. In well rotated fields, the first fungicide spray for leaf spot control should be applied when peanuts reach R3, or when about half the plants in a particular planting have at least one pod starting to develop. In most years, peanuts will reach R3 around July 7. Reapply foliar fungicides every two weeks, or follow the Peanut Leaf Spot Advisory.

The North Carolina Peanut Leaf Spot Advisory is a cooperative effort by the State Climate Office of North Carolina and the Department of Plant Pathology at North Carolina State University. The advisory is a safe way to minimize fungicide applications by spraying only when weather conditions favor disease.

We also provide spray advisories to warn growers when conditions are right for Sclerotinia blight. Sprays for Sclerotinia blight control are necessary only in fields with a history of disease. Growers should start scouting for Sclerotinia blight in early July and follow advisories to determine whether sprays are necessary.

Leaf spot and Sclerotinia advisories are delivered by daily e-mails throughout the summer. Contact Barbara Shew or your county Extension office if you would like to receive peanut disease advisories. Advisories are also available on-line at http://ncsupeanut.blogspot.com/.

For more information about peanut diseases, see 2013 Peanut Information (http://www.peanuts.ncsu.edu/PDFFiles/005279/2013_Peanut_Information_%28NC%29.pdf).

From: Jim Dunphy, Extension Soybean Specialist, and Steve Koenning, Extension Plant Pathologist

Soybean Rust Update

Asiatic soybean rust has now been confirmed in 2013 on soybeans in three states – Avoyelles and Rapides parishes in Louisiana, Gadsden and Jackson counties in Florida, and Baldwin County, Alabama. The closest rust to our North Carolina soybeans is approximately 390 miles from Charlotte, 620 miles from Elizabeth City, 450 miles from Fayetteville, 310 miles from Murphy, 495 miles from Raleigh, 550 miles from Washington, 460 miles from Wilmington, and 455 miles from Winston-Salem, North Carolina.

We do not recommend spraying soybeans with a fungicide to control Asiatic soybean rust at this time. Such pre-bloom applications have seldom improved yields.

The current status of soybean rust in the U.S. can always be found at http://sbr.ipmpipe.org/cgi-bin/sbr/public.cgi.

Written By

Amie NewsomeExtension Agent, Agriculture - Commercial Horticulture (919) 989-5380 (Office) Johnston County

Posted on Jul 1, 2013

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