Southeast Missouri Pest Bulletin No. 2, May 25, 2004

This year I'm trying to include relevant photos in the newsletter to provide additional information on breaking pest situations. But, I realize for some of you who are on a modem, you may not be able to download the newsletter; therefore, each week the newsletter will be posted on the following MU Delta Center webpage http://aes.missouri.edu/delta/news/semopest/index.stm with the corresponding photos. Last week's newsletter has now been posted, and I apologize if you didn't receive the first issue. Again, anyone wishing to receive this and other MU newsletters electronically, I ask that you send me (boydm@missouri.edu) your e-mail address. THANKS! (MLB)

INSECTS & OTHER PESTS
It has been relatively quiet week on the insect front. Thus far, I've only received a few reports about crop pests (ex. thrips in cotton; nematodes, Southwestern corn borer, and stink bugs in corn) infesting fields in the Bootheel. We've also been establishing new moth traps and switching others over to monitor several different insect species. The latest moth trap captures for several crop pests are reported in Table 1. For anybody who may wish to run your own pheromone-baited traps in Missouri, I'm willing to provide you with the lures in exchange for your trap counts.

CORN
Nematodes: I recently received a report from Brian Selle that stubby-root nematodes may be causing damage in Mississippi County corn fields. This nematode species feeds exclusively at the root tips resulting in stunted, stubby roots. Soil populations of this nematode can both increase and decrease with equal abruptness. I spoke with Dr. Allen Wrather, MU State Extension Plant Pathology Specialist, and he said the best means of reducing nematode damage in corn is with an at-planting treatment (ex. Counter). Hopefully, we'll have more information on this pest in next week's issue.

Southwestern corn borer: I've received a couple of reports of southwestern corn borer (SWCB) moth flights, especially around the Parma and Sikeston areas. Any non-Bt corn fields should be closely monitored at this time for SWCB egg masses and hatching larvae. Early detection is the key to timing insecticide applications and minimizing corn borer damage. Once the larvae bore into the plant they are impossible to kill. The recommended MU action threshold for SWCB is 25% of the plants infested with egg masses and small larvae.

For more information on scouting procedures for both the European and southwestern corn borers, obtain a copy of MU guidesheets G7111 (SWCB) and G7113 (European corn borer) at your local MU extension office, here at the MU Delta Center, or from MU Extension Publications.

Stink Bugs: Last week I received a report from Mississippi County of stink bugs feeding in whorl-stage plants. These insects are only sporadic pests in corn, but the risk of stink bug damage increases where wheat is planted as a cover crop and corn is planted without tillage. Stink bug damage is always evident, and symptoms are varied (ex. tiny holes surrounded by dead tissue, twisted leaves or stalks, stunting, wilting).

COTTON
Thrips: I've only received a few calls this past week regarding thrips infestations in cotton fields. As I mentioned last week, the recent heavy rains will likely increase leaching of in-furrow and seed treatments and put young plants at greater risk to thrips feeding damage. I'd also point out with wheat fields rapidly maturing, adult thrips will be migrating to actively growing plants like cotton. The presence of numerous wingless thrips or those with only partially developed wings is a key indicator that at-planting treatments are no longer providing adequate control. This is when a foliar application of recommended insecticide (ex. acephate, Bidrin, dimethoate, Monitor) can be tank-mixed with your glyphosate overspray. The MU recommended action threshold of 1 thrips per plant.

SOYBEAN
Bean leaf beetle: As I said last week I'd closely monitor any early-planted fields near the beetle's prime overwintering sites (ex. woodlots and woody fencerows). The recommended MU action threshold during the seedling stage is 5 or more adults or one damaged plant per row foot. Adults are easily caught with sweep nets, but they frequently drop to the ground when the plants are disturbed. Recommended insecticides for bean leaf beetle control include: carbaryl, chlorpyrifos, methyl parathion, several pyrethroids, and thiodicarb.

PUBLICATIONS
A new MU guidesheet on Missouri's armyworm pests (G7115) should be able very soon at your local extension office and from MU Extension Publications (800-292-0969). This guidesheet includes information on managing beet, fall, true, and yellowstriped armyworms across several cropping systems.

DISCLAIMER STATEMENT
The University of Missouri does not warrant products mentioned in this publication. The use of a trade name does not constitute recommendation of one product over other (generic) products of a similar chemistry.