Southeast Missouri Pest Bulletin No. 15, August 26, 2004

ACKNOWLEDGEMENTS
This is the last, regular issue of the 2004 Southeast Missouri Pest Bulletin, but we will stay in touch if there is any breaking news on pest related issues. On behalf of my co-author Dr. Bobby Phipps and myself we wish to acknowledge the various students for their assistance this summer with the 2004 newsletter. I'd also want to acknowledge the MU regional extension specialists (Tate Castillo, David Guethle, Jeff House, Mike Milam, and Anthony Ohmes) and consultants (Phil Gurley and Victor Roth) for their weekly moth trapping reports this year. I also appreciate all the field reports that I received this year from various agribusiness personnel, consultants, and growers. Your information was very valuable and helpful in putting together this newsletter. (MLB)

MEETING ANNOUNCEMENTS
MU DELTA CENTER HERBICIDE & WEED CLINIC - SEPTEMBER 9th: The MU Delta Center will be offering a herbicide symptom and weed ID clinic on September 9th at the Delta Center's Lee Farm, 8 miles southeast of Portageville, MO at the intersection of county highways T and TT. This clinic targets professional crop advisors including agronomists, consultants, scouts, and retail and manufacturing representatives. Six total continuing education units (CEU) should be available for Certified Crop Advisors (3 CEU's per session). The herbicide symptomology clinic runs from 9:00 AM until noon, and weed identification runs from 1-4:00 PM. A $25.00 registration fee includes either or both clinics as well as lunch. Persons planning to attend are asked to preregister by contacting the Delta Center at 573-379-5431 or Andy Kendig (kendigj@missouri.edu). For more information search out the MU Delta Center website or go directly to: http://www.psu.missouri.edu/deltaweeds. (AK)

MU COTTON TOUR - September 14th: The University of Missouri annual varietial cotton tour will be held at the MU Delta Center Rone Hall on September 14th beginning at 9:00 AM.

ON-FARM RICE STORAGE MANAGEMENT WORKSHOP - OCTOBER 26th: The University of Missouri will be sponsoring a workshop on management of farm-stored rice on October 26th at the Dexter Eagle's Club from 8:30 AM to 3:00 PM. Specialists from the University of Arkansas, Texas A&M University, and USDA-ARS in Manhattan, Kansas will be sharing the latest information on managing stored rice to prevent loss of grain quality from insect feeding damage and other factors. The registration fee for the workshop has been waived, and a free lunch will be provided to those who attend the workshop. I would ask that you pre-register by October 8th so I can get a head count for handouts and the meal. You can contact me by phone (573-379-5431) or e-mail (boydm@missouri.edu). (MLB)

SCOUTING SCHOOL - February 2005: The 2005 MU Delta Center Scouting School will be held nightly (6-9 PM) in February 7-25, 2005. This 3-week course is primarily devoted to learning about crop insect pests and how to scout for them in the field; however, additional classes will focus on plant disease recognition, weed identification and herbicide injury diagnosis, nutrient deficiency diagnosis, and crop growth management. Enrollment is limited to 20 new students, but former students are always welcomed to attend parts or all of the school as a refresher course. The deadline for registering is December 17th. If you are interested in attending the 2005 Delta Center Scouting School and would like to register for it, you can contact me by phone or e-mail.

INSECTS & OTHER PESTS
Insect activity has remained steady over the past week in southeast Missouri. I have received reports about the following crop pests (ex. aphids, armyworms, bollworms / budworms, and plant bugs in cotton; Dectes stem borer in soybean) being active in the Bootheel. The latest moth trap counts are listed in Table 1. (MLB)

COTTON
Crop / Insects: Phil Gurley reports that he has observed a few open bolls this past week. From reports that I've received and observations we've made in the field indicate we are finally seeing a decline in insect counts as the crop cuts out.

Armyworms: I received a report from Phil Gurley that he has treated a couple of fields for beet and fall armyworms. This is the first report that I've received about beet armyworms, and I've usually observed this pest in fields that also had a major pigweed infestation. Beet armyworms (distinctive black dot on either side of the body and above the second pair of true legs) are usually more of a problem as a mid-season, fruit-feeding pest than as a late-season, foliage-feeder. Fall armyworms (smooth-skinned with an inverted "Y" mark on their cream-colored heads) typically infest cotton once nearby corn fields cutout. Since fall armyworms can still damage bolls that are considered safe (NAWF=5 + 350 DD60's) from other pests (ex. bollworms, plant bugs), you should still monitor your crop for this insect. The MU action threshold for this pest is when 4 or more larvae per 100 bolls or blooms are present. Both Bollgard I and conventional cotton fields will remain susceptible to fall armyworm-feeding damage.

Bollworm/Budworm: Moth counts for bollworms were variable again this past week with the counts declining at most locations. Based on reports I received from consultants and observations we've made in the field, we are still seeing an egg lay on lush, green cotton. Hopefully, most of your cotton is beyond the point of spraying for these pests; however, I have received reports of a few fields still being treated. Remember that budworms are more difficult to kill with pyrethroids than bollworms; therefore, it's recommended that you target ¼-inch or smaller budworm larvae with Denim, Steward, or Tracer.

Plant Bugs / Cotton Fleahopper: Nothing new to report on the on-going plant bug situation except that infestations are continuing where the cotton remains lush and green and that a few fields are still being treated.

Root-knot Nematodes: Previously, I've spoken and written about root-knot nematode damage in cotton. As I said before crop-threatening levels of root-knot nematodes are present in some, but not all, cotton fields in southeast Missouri. Typical symptoms of root-knot nematode injury are stunted plants with visible galls (swollen areas) on the roots. (AW)

Be cautious about diagnosing the cause of stunted cotton because other factors such as low soil pH and drought also may cause plants to become stunted. If you have some questions about possible nematode problems in your cotton fields, you should collect soil samples from these fields in late-September to early-October. Samples can then be taken to your local extension office for assistance in processing.

If nematodes are positively identified as causing problems in your fields, you can take precautions next year to prevent this problem from occurring again. Since no cotton varieties are highly resistant to root-knot nematodes, growers should consider using Temik at 3.5-5.0 pounds per acre in-furrow in these fields where nematodes have become a problem. But, the best method for managing the nematode problem is to plant a root-knot nematode resistant soybean variety in the field for one to two years before switching back to cotton. This will cause the nematode population to decline, thus fewer nematodes will be present to damage the subsequent cotton crop.

Following these suggested procedures should give you a better chance of producing higher yields and greater profits. For more information contact Allen Wrather at the University of Missouri Delta Center (Phone: 573-379-5431, e-mail: wratherj@missouri.edu) or check the following Delta Center webpage: aes.missouri.edu/delta

Stink Bugs: Phil Gurley reports that he is still finding a few stink bugs at various locations. Since stink bugs can still damage relatively mature bolls that are generally safe from others pests (ex. bollworms, plant bugs), you still need to continue monitoring your crop for their feeding damage. The recommended action threshold for stink bug infestations is 1 or more stink bug (large nymphs and/or adults) per 6 row feet, OR when 20% of quarter-sized bolls display internal signs of damage and stink bugs are observed in the field. (MLB)

RICE
Rice Stink Bug: Thankfully, stink bugs have not been much of an issue this year based on conversations I had with Amy Beth Dowdy and Wendell Minson at the Rice Farm Field Day. For those of you who are scouting your own fields, I would recommend checking your fields a couple of weeks before harvest for any late stink bug infestations. The issue with these infestations is having too many stink bugs mixed in with the harvested rice, and this 'contamination' can lead to dockage at the elevator.

SOYBEAN
Soybean Aphid: I recently saw a report from southern Illinois of increased soybean aphid activity in double-cropped soybean fields. We still have not observed any economic infestations here in southeast Missouri, but I would suggest checking any late-planted fields for this pest. Soybean aphids are very small, yellowish in coloration, and have distinctive black cornicles or "tailpipes". If you find any colonies of soybean aphids in your fields, please contact your regional extension specialist or myself so we can further document these infestations in Missouri.

Stink Bugs: Nothing new to report on stink bugs infesting soybean fields in the Bootheel, but I would advise monitoring any fields that have developing seeds and are adjacent to corn fields plus the insect's overwintering sites (ex. woodlots). The recommended MU action threshold is 2 or more stink bugs (large nymphs and adults) per 3-row feet as the seeds begin to fill.

STORED GRAIN
With the corn harvest underway, now is the time to prepare your bins so to minimize infestations from stored grain insect pests. Proper stored grain pest control involves several key steps: 1) Sanitation is essential by removing all grain residues from bins, combines, trucks, and augers that are the primary sources of these pest infestations. 2) Maintain proper grain management by keeping grain moisture levels at or below 14% and temperatures within 20 degrees of the outside temperatures. 3) A grain protectant is recommended if the grain is to be stored for three or more weeks at temperatures above 60 degrees F. For more information on insect management recommendations for storing grain on-farm, logon to the following MU AgEBB webpage: http://agebb.missouri.edu/storage/pests/insect.htm

WHEAT
Aphids: I realize wheat planting time is still a few weeks away, but you should start looking at your options for minimizing aphid damage in this year's wheat crop. In the fall, the primary concern about aphids (particularly the bird oat-cherry aphid and greenbug) is their transmission of barley yellow dwarf virus (BYDV) to young seedlings. This virus causes plants to become stunted in the fall and can lead to yield losses the following spring. Shawn Conley, MU Wheat Specialist, has observed a 13-18 percent yield loss caused by the aphid / BYDV complex. Controlling the aphids is the only way of preventing your plants from being infected by this virus.

In the fall of 2003, aphids infested many fields in the Bootheel region and they continued feeding on the plants well into the winter. Certainly, last fall's mild, drier weather was ideal for the aphids, and was a large factor influencing the severity of the aphid and virus problems in our region. Dr. Conley was able to conduct field trials across the state this past field season looking at the impact of different treatment options (including insecticide seed treatments) for managing aphids and virus transmission. Only at the Lamar location did he find a significant yield increase when using just a seed treatment. Dr. Conley thinks the late fall of 2003 allowed the aphid populations to build back up once these seed treatments had "played out". For Bootheel wheat producers, he recommends scouting your fields and using a foliar insecticide spray(s) to control the aphids.

For more information on disease and insect identification in wheat, obtain a copy of MU manual IPM1022 ("Management of Soft Red Winter Wheat") from MU Extension Publications (800-292-0969).