CONFERENCE CONNECTION

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1 Schedule for the Bulletin At least a couple of people have asked me why the Bulletin on the web is not current. And for those of you who receive the Bulletin by mail, you may be wondering why you didn t receive your issue last week. The answer is simple, but I owe you an explanation. There is usually one week in August during which the Bulletin is not published. Last week was the week. However, we didn t inform anyone. Consequently, except for the issue you now hold in your hands or stare at on your computer screen, the most recently published issue of the Bulletin was issue no. 21, August 14, As the summer draws to a close, we change from publishing the Bulletin weekly to publishing it monthly. Therefore, the next three issues you receive will be prepared and mailed in early October, November, and December. FOR IMMEDIATE RELEASE No. 22/August 28, 1998 Thanks to all of you who diligently supplied us with field reports all summer. And thanks especially to all subscribers who continue to support our efforts. Without you, we d have no need to write these words. On behalf of all of the authors in the Department of Crop Sciences, I thank you. Kevin Steffey (ksteffey@uiuc.edu), Extension Entomology, (217) Executive editor: Kevin Steffey, Extension Entomologist Web subscriptions available: For subscription information, phone , or acesnews@uiuc.edu In This Issue Schedule for the Bulletin, 199 Dates, New Name for the Agricultural Pesticides Conference, 199 Developing & Commercializing Resistance Management Strategies, 200 Herbicides as Harvest Aids, 200 Flurry of European Corn Borer Activity; Bt-Corn for 99? 200 Wheat Growers Should Not Forget Hessian Flies, 202 CONFERENCE CONNECTION In this new section entitled Conference Connection, we will keep you informed about conferences, workshops, seminars, and other meetings in which you might be interested. Meetings sponsored by the University of Illinois and by other organizations will be provided intermittently throughout the year. We ll also provide mailing addresses, phone numbers, and e- mail addresses that will allow you to get more information about specific meetings. We hope this service is useful to you. Dates & New Name for the Agricultural Pesticides Conference Dates for the Crop Protection Technology Conference (formerly known as the Agricultural Pesticides Conference, the old Spray School ) have been set for January 6 and 7, Please mark your calendars. Kevin Steffey and I rotate the chairmanship for this conference, and I m at the plate this season. The 1999 program is already beginning to take shape. Our keynote session on January 6 will feature speakers who will address several themes revolving around biotechnology and agriculture. On the first day, presenters will discuss many of the issues concerning drift and its potential implications. Other speakers the first day will describe some of the latest research efforts in the entomology and weed science areas. 199

2 Starting bright and early on January 7, the second day of the conference will begin with presentations focusing on plant pathology issues. Other sessions during the second day include discussions on precision agriculture, on-farm research, fertility and water quality issues, and the Food Quality and Protection Act. The conference will conclude with many presentations on the newest developments from industry. Participants will be exposed to two full days of the latest crop protection technology research from the public and private sector. Please plan to attend! If you have any questions or comments about the 1999 program, please give me a call. More details for the conference will be provided in our October issue of the Bulletin. Mike Gray (m-gray4@uiuc.edu), Extension Entomology, (217) Developing & Commercializing Resistance Management Strategies Subscribers to this Bulletin may be interested to know that Global Business Research, Ltd., is sponsoring an important educational opportunity November 19 20, 1998, in New Orleans. Developing & Commercializing Resistance Management Strategies will look at herbicide-resistant weeds, resistance management programs for Bt crops, novel developments in biotechnology, and many other topics of specific interest to chemical dealers, educators, researchers, and producers. Speakers from notable corporations and universities, including DowAgroSciences, Monsanto, Pioneer, and North Carolina State University, will deliver presentations and panel discussions. For more information on registering for this important conference, call (800) , send an to webmaster@ globalbusinessresearch.com, or visit the Web site at conference98/rm_cover.html. Kevin Steffey (ksteffey@uiuc.edu), Extension Entomology, (217) WEEDS Herbicides as Harvest Aids As crops across Illinois reach maturity and harvest approaches, weeds remaining in fields could potentially present harvest difficulties. Only a few herbicides can be used as harvest aids, helping dry down existing weed vegetation before harvest. We are often asked if any of these harvest-aid herbicides cause nightshade plants to drop their berries, especially in soybean fields. While both Gramoxone Extra and Roundup can cause the leaves of the plants to dry and drop, neither of these herbicides will cause the berries to drop from the plant. Preharvest applications of translocated herbicides may also help suppress weed seed production, but caution must be used because application of these herbicides too soon (with respect to crop developmental stage) may allow some herbicide to move into the developing seeds. Translocated herbicides may also provide some suppression of perennial weed species if enough leaf surface is available for herbicide absorption. Preharvest herbicides for corn. Some formulations of 2,4-D may be applied as preharvest treatments. Applications, generally 1 to 2 pints per acre, should be made after the harddough stage; some formulations are labeled for aerial application. 2,4-D controls only certain broadleaf species and provides no control of grass species. Be cautious about off-target movement of 2,4-D, especially if sensitive plants are growing nearby. Roundup Ultra (glyphosate) may be used as a preharvest treatment in corn. Application rates range from a maximum of 1 quart per acre for aerial applications to 3 quarts per acre for ground applications. Grain moisture should be at 35 percent or less, and plants should be physiologically mature (black layer fully formed). Allow 200 at least 7 days between application and harvest. Applications to seed production fields are not recommended. Preharvest herbicides for soybeans. Gramoxone Extra (paraquat) may be applied as a preharvest treatment at 12.5 fluid ounces per acre. Include 1 quart of NIS per 100 gallons of spray solution. Applications should be made after 65 percent of soybean pods have turned brown or when seed moisture is 30 percent or less. Allow at least 15 days between application and soybean harvest. Roundup Ultra may be used as a preharvest treatment in Roundup Ready and conventional (nonresistant) soybeans. For Roundup Ready soybeans, apply up to 1 quart per acre after loss of green color in soybean pods until 14 days prior to harvest. The combined total of in-crop and preharvest Roundup Ultra applications cannot exceed 3 quarts per acre. Preharvest applications to nonresistant soybeans may be made after pods have set and lost all green color and at least 7 days prior to harvest. Rates range from 1 to 6 quarts per acre, but do not apply more than 1 quart per acre for aerial applications. Do not apply to soybeans grown for seed because a reduction in germination or vigor may occur. Aaron Hager (hagera@idea.ag.uiuc.edu) and Marshal McGlamery (mmcglame@ uiuc.edu), Crop Sciences, (217) INSECTS A Flurry of European Corn Borer Activity, and Bt-Corn for 99? As I have stated previously, European corn borers have been conspicuous by their absence this summer. I recently returned from a series of seminars for dealers in Illinois, Ohio, Michigan, Iowa, and Missouri, and the story is the same throughout most of the Corn Belt. However, we recently received a handful of reports of increases in num-

3 bers of corn borer moths either captured in traps or observed flying at night. Rick Weinzierl, Extension entomologist in the Department of Crop Sciences, informed us that a light trap in northeastern Mason County captured 123, 342, 191, and 207 corn borer moths on four consecutive nights during the latter part of the week of August 17. John Shaw, senior research specialist with the Illinois Natural History Survey, also reported an increase in moth captures in his light trap here in Champaign County during that same week. Some folks in attendance at the field day held at the Northwestern Agricultural Research and Demonstration Center near Monmouth (Warren County) told me that they have seen many moths flying around at night. And Randy McElroy with DeKalb Genetics told me on August 26 that he, too, had been observing large numbers of corn borer moths flying at night in counties south of I-70. We are not certain what these late moth flights mean, but they are worth noting. In southern Illinois, flights of European corn borer adults at this time of year usually represent the beginning of a third generation. However, third generations of corn borers in central and northwestern Illinois are not common. Are we witnessing a later-thannormal moth flight this year? We can only speculate an answer to that question, and only time will tell whether corn borers complete their development before declining temperatures and light:dark ratios trigger diapause. Remember, corn borer larvae must reach maturity (fifth instar) to enter diapause and survive the winter. If the moths that are flying now lay eggs, some of the larvae in some areas of Illinois likely will not reach maturity and, thus, will not survive the winter. corn borers are subeconomic, as they were in Consequently, some people may decide that Bt-corn for management of corn borers in 1999 is not necessary. However, we try to impress upon growers that using Btcorn for management of corn borers should be a long-term investment, not a short-sighted tactic used or not used one year based upon what happened or didn t happen the year before. The correlation between densities of corn borers one year and densities the next year usually is not good. Figure 1 shows the average number of corn borer larvae per stalk assessed during annual fall surveys of corn fields from 1987 through During this 10- year period, average densities of second-generation corn borer larvae ranged from 0.3 per stalk (1992) to 3.48 per stalk (1989). On more than one occasion, years when densities of corn borer larvae were large (e.g., 1989, 1991) were followed by years when densities were relatively low (e.g., 1990, 1992). The reverse was also true: some years when densities of corn borer larvae were low (e.g., 1988) were followed by years when densities were very large (e.g., 1989). Considering this information, one must ask the question Will corn borer densities be small or large in 1999? Obviously we will not know the answer to the question for many months. The point I am making is that the decision to use or not use Bt-corn to manage European corn borers cannot be based upon short-term population fluctuations. In areas where economic infestations of corn borers are relatively frequent (e.g., 7 or 8 years out of 10), Bt-corn is wise investment for management of corn borers. In areas where economic infestations of corn borers are relatively infrequent (e.g., 2 or 3 years out of 10), growers should really question whether purchasing and planting Bt-corn is a wise investment. A final note: Growers who purchase Bt-corn and will plant it in 1999 should consider how they will implement their resistance management plan, primarily the extent and placement of non-bt-corn refuge. As Btcorn gets planted on more and more acres, concern about the development of corn borers resistant to the Bt endotoxin increases. We ll offer more details in a future issue of the Bulletin, but we want to plant the seed (pardon the pun) of resistance management now so growers will begin thinking about it seriously. Kevin Steffey (ksteffey@uiuc.edu), Extension Entomology, (217) A comment about Bt-corn would be appropriate at this time. Many growers who purchased and planted Bt-corn this year will wonder whether the investment was worth it. After all, growers get no return on their investment for Bt-corn when densities of Figure 1. Densities of European corn borer larvae (ECB/stalk) assessed during fall surveys of corn fields in Illinois,

4 Wheat Growers Should Not Forget About Hessian Flies While glancing at the fall 1998 (vol. 4, no. 4) issue of the Illinois Wheat Association Newsletter, I came across an article about Hessian flies written by Roger Ratcliffe, research entomologist, USDA-ARS, West Lafayette. Roger is a recognized expert on Hessian flies and resistant wheat varieties, and he has been monitoring Hessian fly populations in southern Illinois for many years. I think his observations are important, so I ll excerpt some of them from the article. One of the main reasons Roger and his associates monitor Hessian fly populations is to assess the specific biotypes of the insects collected. Biotypes of the Hessian fly become prevalent in the field in response to exposure to resistant wheat varieties. Over a period of 6 to 8 years of continual exposure to wheat varieties carrying specific genes for resistance, fly populations change so that new virulence genes become prevalent and render the resistance ineffective. All Hessian fly populations collected from southwestern Illinois during this period ( ) were largely biotype L (84 to 100 percent), with a low frequency of biotypes D and G. Illinois counties represented in these collections were Alexander, Franklin, and Randolph; however, it is likely that Hessian fly populations throughout the soft winter wheat area of Illinois would be very similar in composition. Hessian fly populations in the southernmost Illinois counties may still contain low frequencies of biotype D, but this would have little influence on the effectiveness of resistance genes currently available in wheat varieties adapted to the area. Resistance gene H5 is effective against biotype D, but the percentage of D is so low in field populations that wheat varieties carrying H5 resistance would be largely ineffective. Roger s findings of a predominance of biotype L in Illinois populations of Hessian flies are quite important. Biotype L has the ability to infest and injure wheat varieties that carry one or more of the four resistance genes that presently are available in soft winter wheat varieties. Thus, the resistant wheat varieties presently available to Illinois wheat growers are largely ineffective in controlling the Hessian fly. Fortunately, fly populations have remained low enough that little injury occurs in most fields, but the potential for more severe injury is present. This makes it very important for growers to utilize cultural practices that help reduce exposure of wheat to high fly populations. Two cultural control methods that are effective are seeding wheat after the peak emergence period of the fly in the fall (fly-free date) and destruction of volunteer wheat that serves as an over-summering site for flies that develop to the pupal or flaxseed stage in the spring and emerge as adults in the fall. Roger and his colleagues have developed a new soft red winter wheat variety that is resistant to Hessian fly biotype L. However, it probably won t be available for planting until the fall of Therefore, it is important that wheat growers seriously consider the cultural tactics of keeping densities of Hessian flies low. We encourage all wheat growers to plant wheat in 1998 after the fly-free dates that are provided in Table 1 for all counties of Illinois. Implementation of this cultural practice in 1998 could prevent economic losses in Kevin Steffey (ksteffey@uiuc.edu), Extension Entomology, (217)

5 Table 1. Average date of seeding wheat for the highest yield. Average date of Average date of seeding wheat for seeding wheat for County the highest yield County the highest yield Adams Sept. 30 Oct. 1 Lee Sept Alexander Oct. 12 Livingston Sept Bond Oct. 7 9 Logan Sept. 29 Oct. 3 Boone Sept Macon Oct. 1 3 Brown Sept. 30 Oct. 2 Macoupin Oct. 4 7 Bureau Sept Madison Oct. 7 9 Calhoun Oct. 4 8 Marion Oct Carroll Sept Marshall Putnam Sept Cass Sept. 30 Oct. 2 Mason Sept. 29 Oct. 1 Champaign Sept. 29 Oct. 2 Massac Oct Christian Oct. 2 4 McDonough Sept. 29 Oct. 1 Clark Oct. 4 6 McHenry Sept Clay Oct McLean Sept. 27 Oct. 1 Clinton Oct Menard Sept. 30 Oct. 2 Coles Oct. 3 5 Mercer Sept Cook Sept Monroe Oct Crawford Oct. 6 8 Montgomery Oct. 4 7 Cumberland Oct. 4 5 Morgan Oct. 2 4 DeKalb Sept Moultrie Oct. 2 4 DeWitt Sept. 29 Oct. 1 Ogle Sept Douglas Oct. 2 3 Peoria Sept DuPage Sept Perry Oct Edgar Oct. 2 4 Piatt Sept. 29 Oct. 2 Edwards Oct Pike Oct. 2 4 Effingham Oct. 5 8 Pope Oct Fayette Oct. 4 8 Pulaski Oct Ford Sept Randolph Oct Franklin Oct Richland Oct Fulton Sept Rock Island Sept Gallatin Oct St. Clair Oct Greene Oct. 4 7 Saline Oct Grundy Sept Sangamon Oct. 1 5 Hamilton Oct Schuyler Sept. 29 Oct. 1 Hancock Sept Scott Oct. 2 4 Hardin Oct Shelby Oct. 3 5 Henderson Sept Stark Sept Henry Sept Stephenson Sept Iroquois Sept Tazewell Sept. 27 Oct. 1 Jackson Oct Union Oct Jasper Oct. 6 8 Vermilion Sept. 28 Oct. 2 Jefferson Oct Wabash Oct Jersey Oct. 6 8 Warren Sept JoDaviess Sept Washington Oct Johnson Oct Wayne Oct Kane Sept White Oct Kankakee Sept Whiteside Sept Kendall Sept Will Sept Knox Sept Williamson Oct Lake Sept Winnebago Sept LaSalle Sept Woodford Sept Lawrence Oct

6 CES Newsletter Service University of Illinois at Urbana-Champaign 69 Mumford Hall 1301 West Gregory Drive Urbana, IL Presorted First Class Mail U.S. Postage Paid Permit No. 75 Champaign, IL Return Service Requested The Pest Management & Crop Development Bulletin is brought to you by the Cooperative Extension Service and Information Technology and Communication Services, College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana-Champaign; and the Natural History Survey, Urbana, IL. This newsletter is edited by Mary Overmier and formatted by Oneda VanDyke, ACES/ITCS. Helping You Put Knowledge to Work State County Local Groups U.S. Department of Agriculture Cooperating The Cooperative Extension Service provides equal opportunities in programs and employment. 204