Category Archives: Insect

Resistance management of corn earworm

The attached 4-page pdf contains information on this year’s corn earworm moth vial tests, resistance management suggestions, links to Dr. Herbert’s corn earworm threshold calculator and his soybean chapter in the 2012 Virginia Cooperative Extension Pest Management Guide, a list of insecticides registered for use in soybean, and the results of Dr. Herbert’s 2011 corn earworm efficacy trials in soybean. Please click “More” to view this document. Additional information: resistance-mgmt-advisory-pdf

Brown marmorated stink bug black light trap averages for week ending Aug. 9, 2012

BMSB trap catches were low in most locations, except Petersburg (13.9/night) and Warsaw (2.8/night). Mark Kraemer, Entomologist at Virginia State University, reported that he was seeing BMSB adults and second instars in Asian Long Beans, and mentioned that a co-worker found some adults on vegetable soybean along a field edge next to the woodline. Prince George-Disputanta had been getting zero’s this season, but this week averaged 0.9 per night. Isle of Wight had a suspected BMSB captured in its trap; we are in the process of confirming the species. Please see the table (attached pdf file) for more details. Additional information: bmsb-blacklight-table-12-pdf

Corn earworm moth black light trap captures for the week ending Aug. 9, 2012

We are fortunate to have added several new black light traps in the past few weeks, including ones in Surry County (Glenn Slade), Isle of Wight (Janet Spencer), and Virginia Beach-West Neck (Roy Flanagan). Moth counts averaged from 3 to 26 per night this past week; please see the attached table (pdf file) for more details. Additional information: blacklight-table-12-pdf

Kudzu bug and brown marmorated stink bug distribution map–Aug. 9, 2012

Dr. Herbert mentioned these items in his Aug. 8 advisory; here is the distribution map for kudzu bug (host crops = kudzu and/or soybean) and BMSB (host crop = soybean), attached as a pdf file. Thanks to the following scouts for their efforts: Ed Seymore, Jamie Hogue, Tami Carlow, and the Entomology Crew at the Tidewater AREC. Additional information: va-bmsb-kudzu-bug-2012-pdf

Corn earworm resistance monitoring update for Aug. 9, 2012

Resistance monitoring results for this week in Suffolk (based on 222 vials tested) indicated 30.1% of corn earworm moths surviving the 24-hour exposure period to cypermethrin. This brings the seasonal average to 38.2% survival (1,586 vials tested). The 2011 and 2012 line graphs are attached as a pdf. Additional information: cew-cypermethrin-2yr-pdf

Corn earworm, stink bug and kudzu bug update

The pyrethroid vial tests are still showing high levels of corn earworm survivorship. Thursday, Sean Malone will post the line graph including this week’s vial test totals, but as of now, we are still getting about 45% survivors. This is important to consider when selecting insecticides for ‘worm’ control in soybean fields. We are now beginning to see corn earworms feeding on young pods in some fields. In others, we are not finding any, or just a few. Each field is a separate case and each should be sampled to determine if earworms are present in numbers that warrant treatment. You can find earworms in many peanut fields, but as stated earlier—if you want to treat them, consider it to be recreational, not economic.

We have been sampling sorghum heads for worms this week in four different locations and all but one have levels worm levels that exceed the 1 worm/head threshold. Some samples reached 30-55 per 10 heads, way over threshold. Products labeled for worm control in sorghum are limited (at least all we could find) to Baythroid, Karate/Warrior, Lannate, Mustang Max or Blackhawk (the new Tracer). Of those, Lannate will give the quickest kill but has essentially no residual activity. But, residual activity should not be an issue. If worms are killed, heads will be matured beyond attractiveness before any additional worm infestations would occur. The pyrethroids should also do pretty well, unless pyrethroid resistance becomes an issue in sorghum and we are not sure about that. If spraying sorghum, only the heads need to be treated, not the foliage, so use a sprayer configuration/gallons/pressure that directs as much spray as possible to the heads. That is where the ‘action’ is.

Brown marmorated stink bug populations are still very slow to develop across the state, at least as best we can determine. Since last week, we have added three new counties where low numbers have been found in soybeans: Essex, Appomattox, and Louisa Counties. We are tracking these to see if treatments may be needed. Like last year, we are going to recommend and strongly encourage field edge treatments.

Kudzu bug encounters have slowed and we have added only one of two new counties, Suffolk for one. We are still only finding low numbers of adults and no eggs or nymphs. Hopefully we will not experience any outbreaks.