North Carolina Pest News – August 9, 2013 (Field & Forage Crops)

— Written By Amie Newsome and last updated by Nikki Davis

NORTH CAROLINA COOPERATIVE EXTENSION SERVICE
North Carolina State University * College of Agriculture & Life Sciences
Departments of Entomology and Plant Pathology * Raleigh, NC 27695

NORTH CAROLINA PEST NEWS
Volume 28, Number 18, August 9, 2013

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

From: Jack Bacheler, Extension Entomologist

Cotton Insect Update

If calls from consultants, agents and producers were any indication, stink bugs and their damage to cotton bolls continued to be front and center this past week. With our cotton crop looking anywhere from good to mostly fair to poor depending on planting date and seasonal and recent weather patterns, it’s probably easy to overlook stink bug damage. Both plant bugs and especially stink bugs and their damage vary widely across North Carolina, but are generally at much higher levels that we’ve seen during the past few years. On the plus side, though underway in southern North Carolina since late July, the status of our “major” bollworm moth flight in central and northern North Carolina is difficult to pinpoint so far this year due to presently low moth levels in many areas. I expect this flight to pick up during the next few weeks. This flight will likely be prolonged, due in part to the delayed drying down of field corn.

Our main scouting emphasis at this point should be placed on examining the inside walls of 1-inch diameter bolls for warts and/or stained lint (any amount of even subtle damage is scored as a damaged boll). Damaged boll levels are very high in some fields, with a report of more than 60% internal damage in one central North Carolina field this past week. Although we have heard from producers and some consultants reporting boll damage in the single digits to the high teens, boll damage in the 20-plus percent range are being found in other fields.

Be sure to observe the 10% damaged boll threshold level during weeks 3 to 5 of the bloom period and consider extending this protective threshold into week 6 this year for our late crop, perhaps being followed by a 20% threshold during week 7 of bloom. Please refer to our web-based stink bug decision aid app for additional information about stink bug scouting, identification, dam-age and other information (http://ipm.ncsu.edu/cotton/insectcorner/sbapp2/index.html).

Insecticides targeted for stink bugs generally also do a good job with plant bugs. Although Bidrin and Bidrin XP II offer excellent control of stink bugs and plant bugs, be aware of these products’ 6-day reentry interval.

If present in moderate to high levels, stink bug damage can result in significant yield losses. In making spray/no-spray decisions, remember that the cost of the treatment and insecticide typically translates into having to save proximately 10 to 12 pounds of lint.

In driving back from eastern North Carolina Wednesday, August 7, it was easy to spot a number of fields of stunted cotton plants blooming “out the top”, and well into cutout. It seemed odd to realize that these fields were in need of several more timely rainfalls to make even a decent crop. As is so often the case, a few other cotton fields looked like they could be headed toward 2 bales.

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

Soybean Rust Update: August 8, 2013

Asiatic soybean rust was confirmed in South Carolina commercial soybean fields in Orangeburg County, and at the Edisto Research Station near Blackville, South Carolina. Soybean rust has also been identified in Desha County, Arkansas, two new counties in Georgia, four new counties in Alabama and two new counties in Mississippi. This finding puts rust closer yet to all our soybeans in North Carolina except those in the far western part of the state, but still not close enough to warrant a recommendation from us to spray for the disease. The closest confirmed rust on soybeans to our North Carolina soybeans is now approximately 120 miles from Charlotte, 325 miles from Elizabeth City, 155 miles from Fayetteville, 115 miles from Murphy, 205 miles from Raleigh, 260 miles from Washington, 175 miles from Wilmington and 185 miles from Winston-Salem, North Carolina.

Rust has now been confirmed this year on soybeans in 28 counties/parishes in seven states (Arkansas, Alabama, Florida, Georgia, Louisiana, Mississippi and South Carolina).

We have received sentinel plot samples this week in the Plant Disease and Insect Clinic from Bertie, Johnston, Lenoir and Scotland counties, North Carolina. Soybean rust was not detected in any sample.

Rust has progressed at a much faster rate this year than in years past. With a late soybean crop, the odds of needing to apply fungicides are increased. Now is the time to check spray equipment and be sure to have the proper nozzles for applying fungicides. You may also want to locate sources of fungicides.

We do not recommend spraying soybeans that have not started blooming with a fungicide to control Asiatic soybean rust. Once soybeans start blooming, we would recommend spraying if rust has been confirmed within 100 miles of the field, and if the soybeans do not yet have full sized beans in the top four nodes of the plants.

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

Photo of Amie NewsomeAmie NewsomeExtension Agent, Agriculture - Commercial Horticulture (919) 989-5380 (Office) amie_newsome@ncsu.eduJohnston County, North Carolina
Updated on Aug 15, 2013
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