INSECTS AND WEEDS IN FOCUS

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1 INSECTS AND WEEDS IN FOCUS Web site: VOL. XXXII NO. 5 ENTO/SCS May 24, 2007 GENERAL CROP CONDITIONS FLEAHOPPERS & OTHER INSECT PESTS IN COTTON SPIDER MITES IN CORN HIGH POTENTIAL FOR SORGHUM CHARCOAL ROT IN LATE PLANTINGS COASTAL BEND COUNTY AGRICULTURAL TOUR SCHEDULE INTERESTING INSECTS GENERAL CROP CONDITIONS Crops are currently in good condition, but the situation could change rapidly over the next week. W e need rain now! to maintain a good crop yield for corn and sorghum; possibly by the time this newsletter is received that rain would have occurred. Arthropods to watch for in cotton include fleahopper, bollworm, and mites; in sorghum rice stink bug, headworms, sorghum webworm, and sorghum midge; and in corn banks grass mite, fall armyworm, and to the northeast, sugarcane borer. FLEAHOPPERS & OTHER INSECT PESTS IN COTTON The cotton fleahopper seems to be the most widespread insect pest in cotton in the Lower Gulf Coast. Two and sometimes 3 treatments have been applied to protect the developing crop in areas where numbers are the greatest. We have a fleahopper timing experiment which should reveal excellent information as to the best time to apply insecticide in relation to their numbers. We do plan to obtain plant mapping and yield information from the study. W e have observed higher rates of square retention where fleahopper treatments have been applied. I still suspect some fruit loss very early in the fruiting of the crop will actually improve the overall yield potential due to a better plant structure for crop production. It appears to be shaping up that way in our field experiment; there may be some surprises in that study, however. SPIDER MITES IN CORN Banks grass mites were found in spots in a corn field in San Patricio County this week. They had developed to fairly large numbers in a spot that was noticed from the nearby road. These mites first appear on the lower leaves, but may move upward until all the leaves are affected and killed. Heavy infestations cause extensive webbing on the leaves and may be associated with stalk rot and lodging. Historically, mites on corn in our region have not been a problem. I do not expect widespread infestation, but the situation should at least be noted and fields watched for mite population development. W e also see the mite destroyer (small black lady beetle and the grayish larva) feeding on these mites. Another good predator on the mites is a straw colored thrips with three spots (spotted thrips). A good rain would also help to correct the situation. Outbreaks are favored by hot, dry weather, use of foliar insecticide to control other pests, and high fertilizer use. Detailed information is available in Texas Cooperative Extension Publication E-400 dated May 2006 titled Managing Insect and Mite Pests of Texas Corn. The publication is available at s/e_400_corn_guide_2006.pdf Mite damage is any light-colored (chlorotic) areas on the plant that result from mite feeding. Remember to look at all leaves on the plant to estimate how much of the total leaf area is damaged by mite feeding. Do not base the damage estimate on infested leaves only, or the damage rating will be overestimated. Dead leaves equal 100 percent damage for that leaf. Now, calculate the average percentage of the leaf area damaged. If both the percentage of the leaves infested and the percentage of the leaf area damaged equal or exceed the values for the crop on the table below, it is time to spray. Miticide suggestions are provided in the following table. Adequate control has not been found possible below 5 gallons total volume per acre. In addition to miticides listed in the table corn growers in other regions of Texas often use a combination of dimethoate 4EC (1.0 pints/acre) + bifenthrin 2EC at 0.06 to 0.08 lb active ingredient per acre. It should be noted that the lower rate of bifenthrin is below the lowest rate shown on the label. The banks grass mites in our region should be easier to control than other areas of Texas. 1

2 application can be made per year. Do not plant small grains in rotation within 82 days after application. Spiromesifen: Do not use more than 8.5 oz in any 14-day interval, and do not apply more than 17.0 oz per season or make more than two applications per season. The preharvest interval (PHI) is 5 days for green forage and 30 days for grain or stover. Use a minimum application volume of 10.0 GPA if applied by ground and 5.0 GPA if applied by air. Follow label instructions for chemigation. Sulfur: This is the only material that has been partially effective in the Trans-Pecos area of Texas. Thorough plant coverage is required. HIGH POTENTIAL FOR SORGHUM CHARCOAL ROT IN LATE PLANTINGS Some sorghum plantings made after March 31 seem to be in trouble on the Lower Gulf Coast with no significant measurable rain received in the past 60 days. Most of the rain events have not been significant (less than ½ inches at a time). The exception was March when 1.8 inches was received. Added to that, our February was the driest February on-record at Corpus Christi, with only 0.05 inches. Therefore, sorghum st planted after April 1 is getting into trouble keeping up with water demands for plant structure and yield. Collectively, the past 120 days have been very dry. Remarks Bifenthrin: Research results have indicated that spider mites in some areas of Texas are resistant to Bifenthrin, especially in the High Plains. Bifenthrin will not control resistant populations. ULV applications are prohibited. Bifenthrin is often used in combination with dimethoate. Carbofuran: Do not make more than two foliar applications per season or more than one foliar application if Furadan 4F was used as a soil application. Do not use Furadan as a foliar treatment on seed corn. Do not enter treated fields within 14 days of application unless full protective equipment is worn. Dimethoate: It is not labeled for Trans-Pecos area of Texas. This product has often been used in combination with pyrethroids for control of mites. There is no demonstrated advantage to mixing dimethoate with Propargite. Heavy infestations may require an alternate chemical. Propargite: Ground application must use a minimum of 20 gallons of water per acre. A minimum of 5 gallons of water per acre are required for aerial application. Only one Earlier planted sorghum looks fair to good around Corpus Christi, but two good showers in May would have produced 5000-pound grain instead of the pound grain we will probably have. There are several tillers in sorghum where the stands were not as full. For those thinking about pre-harvest conditioning with glyphosate, take a good look at the sorghum before treating it to ensure that charcoal rot is not starting to develop. Sorghum hybrids not having a great degree of stay green bred into their plant characteristics, will usually sacrifice carbohydrates in the stalks to fill out the grain that is being developed. Stay-green plants will remain green 3-5 days longer than other sorghum hybrids, allowing these plants to not shut-down as fast. As carbohydrates are removed from the stalks, nonstay-green plants tend to dry-down more rapidly. Lodging becomes more prevalent when a certain soilborne fungi, Macrophomina phaseolina (see Fig.1), colonizes the stressed and dying tissues and charcoal rot develops. If there is a lot of weight in the panicles, the plant may collapse or go down with the first big wind. 2

3 Some fields of sorghum may require pre-harvest conditioning for a cleaner, more efficient harvest. The use of Roundup Ultra Max, Weather Max or counterpart products at less than 30% grain moisture can help reduce weed problems, accelerate drydown, increase harvest speed or help to grab grain that didn't fully exert. Additionally, it is the first step in stopping stubble re-growth, eliminates the shredding operation and immediately stops further use of soilstored moisture. Using W eather Max at 22 oz/ac will allow harvest in just 7-10 days. Best results are obtained with 17 pounds of dry ammonium sulfate per 100 gallons of spray solution and using 5-10 GPA (ground application), and 3-5 GPA (by air). Of course this practice is not recommended if there are visible signs of charcoal rot appearing. In marginal situations, don't treat any more sorghum acreage than you are able to promptly harvest. If weeds are heavy, you may want to increase the Roundup Ultra Max or Weather Max to oz/ac. If using generic glyphosate, you will need a full quart of the 4-lb material. The elimination of green weeds and plant material maximizes clean, dry grain and the early harvest could be a good way to beat the weather. Every year sunflowers, pigweed, Texas panicum and johnsongrass make grain moisture higher than it should be. Grain on tillers may be substantially wetter than main stalk panicles. Seed in the bottom of the panicle is the last to mature and dry down. Sorghum grain that has a black layer (black spot on the bottom of the seed where it was connected to the plant) is fully mature and will not continue to increase in weight (see Fig. 2). Where there are wide swings in maturity, judge maturity by the majority of the plants that you would like to take to harvest. Pre-harvest conditioning has a chance of accelerating lodging if there is a lot of charcoal rot developing in the fields. Prompt harvest is recommended, but the 7 day minimum is necessary for the glyphosate to fully kill and dry-down the plant. A pre-harvest treatment makes it easy to obtain grain that has stabilized to a safe moisture storage level. This will help prevent discounts for high moisture grain. Many of these fields over the Lower Texas Gulf Coast may require pre-harvest conditioning for a cleaner, more efficient harvest. SDL COASTAL BEND COUNTY AGRICULTURAL TOUR SCHEDULE Listing of dates for agricultural tours in the region are provided below along with telephone numbers to check on details and to see if any changes have been made in dates. Most of the tours are to row crop locations, others are range and pasture in nature, and several include both row crops along with range and pasture SDL COUNTY DATE Bee 361/ June 1- AM Karnes 830/ June 1 - PM Jim Wells 361/ June 5- PM San Patricio 361/ June 6- PM Nueces 361/ June 8- AM&PM Jackson 361/ June 11- PM Goliad 361/ June 12 - AM Kleberg 361/ June 12 - AM DeWitt 361/ June 12 - PM Refugio 361/ June 13-AM&PM Lavaca 361/ June 14 - PM Live Oak 361/ , ext. 115 June 15 - PM Wilson 830/ June 19 - AM Calhoun 361/ June 19 - PM Fort Bend 281/ June 20 - AM Colorado 979/ June 20 - PM Matagorda 979/ Wharton 979/ June 21 - AM Victoria 361/ June 21 - PM Luling Foundation 830/ June 22 - AM Fayette 979/ June 27 - PM 3

4 Canola Seed Yields Good for 2007 Oilseed yields were similar for canola hybrid performance tests on the Ring Brothers Farm in San Patricio County and the tests conducted on the Texas A&M Research and Extension Center at Corpus Christi, Canola has been planted in a number of performance tests these last six years, looking for the development of an alternate crop for region that could be planted in November and harvested in April. Since our interest in edible oils was tied to the price paid for canola (FOB) and to US and Canadian production demands, things have changed with the development of bio-diesel production facilities and alternative energy sources. These two test locations show that yields between 1500 and 2000 lbs/a are possible even when conditions are fairly dry. As oil seed prices move from cents/lb to as much as cents/lb, new looks at many oilseed crops may occur in 2007 and Variety Table 1. Canola seed yields observed at the Texas A & M Research & Extension Center, Corpus Christi, Nueces County, AVG moisture Avg pop/a Avg yld (lb/ac) Cargill 06H Cargill 06H Cargill 06H Cargill 03H Cargill 03H Hyola 357mag IS Dekalb Dekalb Average Table 2. Comparison of bloom date, percent moisture, and yield per acre from machine harvest, Ring Farm, Sinton, Texas, May 15, Variety Bloom Date (% ) Moisture Yield 1 (lbs./acre) DKL (108,832 seed/lb) 3/ ,466 IMC 209RR (119,265 seed/lb) 3/ ,527 Cargill 03H252 (89,937 seed/lb) 3/ ,557 Cargill 06H990 (77,043 seed/lb) 3/ ,619 DKL (32-inch rows) 3/ ,680 Hyola 357 Magnum (81,676 seed/lb) 2/ ,727 DKL (123,590 seed/lb) 3/ ,727 Cargill 06H991 (66,919 seed/lb) 3/ ,744 Cargill 03H631 (90,891 seed/lb) 3/ ,806 IS 7145RR (143,493 seed/lb) 3/ ,850 Cargill 06H992 (77,588 seed/lb) 3/ ,868 Average 7.0 1,688 1 Yield is adjusted to 10% moisture. 4

5 For more information contact: Roy D. Parker Extension Entomologist Stephen D. Livingston Extension Agronomist Agnes, Corpus Christi, TX (361) , Fax (361) View our newsletter earlier on the internet at Also pest management information is available at ************************************************************************************************************************************************************************************************ ********************** Educational programs conducted by Texas Cooperative Extension serve people of all ages regardless of socioeconomic level, race, color, sex, religion, handicap or national origin. The information given herein is for educational purposes only. References to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Texas Cooperative Extension is implied. The Texas A&M University System, U.S. Department of Agriculture, and the Commissioners Courts of Texas Cooperating 5