Integrated Pest & Crop Management Newsletter University of Missouri-Columbia Vol. 16, No. 11 Article 1 of 5 June 9, 2006 Bean Leaf Beetle Problems Build in Slow-growing Soybean By Wayne Bailey Numbers of bean leaf beetle adults continue to increase in northern and central Missouri counties. Slow soybean germination and growth due to drought conditions allow for increased damage by beetles migrating into soybean fields by overwintering adults. The economic threshold of 5 beetles per foot of row and 30 percent defoliation is a starting point, but drought conditions and mortality of soybean seedlings also must be considered. If an insecticide application is necessary to reduce adult BLB numbers, use one of the recommended insecticides listed in the following table. This table contains a correction from an earlier version of the table published in the newsletter. FMC has a label change for Mustang Max use on bean leaf beetle in soybean which reduces the rate to the levels listed in this table. Be sure to follow all label directions, precautions, and restrictions when using insecticides. Chemical Name Product Name Rates: Amount of Product /acre (unless otherwise noted) permethrin *Ambush 3.2 to 6.4 fl oz esfenvalerate *Asana XL 5.8 to 9.6 fl oz cyfluthrin *Baythroid 2 0.8 to 1.6 fl oz dimethoate Dimethoate; Dimatesee see specific label methomyl *Lannate LV 0.75 to 1.5 pts methomyl *Lannate SP 0.25 to 0.5 lb thiodicarb *Larvin 3.2EC 18 to 30 fl oz chlorpyrifos *Lorsban 4E 1 to 2 pts zeta-cypermethrin *Mustang Max 2.0 to 2.8 fl oz chlorpyrifos *Nufos 4E 1 to 2 pts methyl parathion *Penncap-M 2 to 3 pts permethrin *Pounce 3.2EC 2 to 4 fl oz gamma-cyhalothrin *Proaxis 1.92 to 3.2 fl oz carbaryl Sevin XLR Plus 1 to 2 pts lambda-cyhalothrin *Warrior 1.92 to 3.2 fl oz * indicates Restricted Use Wayne Bailey Entomology 573-864-9905 cell ********************************************************************* Article 2 of 5 June 9, 2006 Field Crop Disease Observations -- June 5, 2006 By Laura Sweets Wheat There hasn’t been much change in the wheat disease situation over the last week. Barley yellow dwarf has been the most widespread and serious disease problem throughout the state this season. Foliage diseases such as Septoria leaf blotch, leaf rust and stripe rust have not been widespread or severe. In most cases they have come in late enough in the season that impact on yield should be minimal. Loose smut has been severe in some fields. This disease is best controlled through the use of disease-free seed or systemic fungicide seed treatments. Scab has been developing in some fields but does not appear to be a major problem statewide. Corn Unfavorable weather conditions are probably the main cause of corn problems thus far this season. Yellowing and stunting of plants has been reported from several areas of the state. In some cases these plants have poor root systems, especially very shallow root systems that run out almost parallel to the soil surface. Dry soils, compaction and other such factors could be causing this poor root system development. Some of these plants are also showing crown discoloration and/or crown decay. Very low levels of Stewart’s bacterial wilt and anthracnose have been reported. Soybeans Thus far, there have been few calls or questions on soybeans. Early season soybean diseases are usually evident during June so be on the lookout for symptoms of Pythium seed decay, Phytophthora seedling blight, Rhizoctonia root rot and Fusarium root rot. Septoria brown spot can develop early in the season but we have seen very little of this foliage disease yet this year. Laura Sweets Ag. Ext.-Plant Sciences 573-884-7307 ********************************************************************* Article 3 of 5 June 9, 2006 WeedSOFT Yield Loss and Tank Mix Calculators Now Available on the Web By Kevin Bradley The WeedSOFT yield loss and tank mix calculators are now available on the web free of charge at the following site: http://weedsoft.unl.edu/weedsoftApps.htm. These calculators are the same tools offered as components of the WeedSOFT software which typically costs users $50 to purchase. If you are not familiar with WeedSOFT, this program is a decision support system (DSS) designed to assist growers, consultants, and extension agents in making both proactive and reactive weed management decisions. WeedSOFT provides you with the treatment information you need according to your specific field conditions while factoring in economic and environmental principles. The software also contains other management tools such as the yield loss and tank mix calculators. The yield loss calculator is a tool that enables you to estimate the season-long yield loss, as well as the yield loss that has already occurred, for corn and soybeans that are at a particular growth stage. It will also estimate the additional yield loss that may occur if you delay treatment. The tank mix calculator is a tool that enables you to calculate the amount of herbicide needed for a field and the amounts to add per tank load. More information on the WeedSOFT software can be found at http://weedsoft.unl.edu/. Kevin Bradley 573-882-4039 ********************************************************************* Article 4 of 5 June 9, 2006 Corn Color Predicts Nitrogen Needs By Duane Dailey The green color of corn leaves offers a quick check on the most economical level of nitrogen fertilizer to apply to a growing crop, a University of Missouri soil scientist said. "Leaf color measurements are more closely related to the most profitable nitrogen fertilizer rates than any soil test," said Peter Scharf, who cooperated in a fertility study with scientists in seven Corn Belt states. Results of the leaf color study are in the current issue of Agronomy Journal, a major scientific publication. The scientists report on 66 nitrogen experiments on corn. "Traditionally corn producers have applied generous rates of nitrogen fertilizer because it was relatively inexpensive," Scharf said. "Corn is so responsive to nitrogen that being caught short can be a disaster." Sharp increases in the price of nitrogen fertilizer are causing corn producers to re-think this strategy. The soil scientists measured yields at each nitrogen rate, which allowed them to calculate the most profitable rate of fertilizer in each of the 66 fields. They used a wide range of soil nitrogen tests in each field, along with the in-season corn-leaf color measurements. The scientists used a Minolta chlorophyll meter to measure leaf color. They found readings from this meter were more closely related to the most profitable rate than any of the traditional soil tests. "This suggests that corn color may be one of the best ways to predict how much nitrogen fertilizer to apply," Scharf said. Good predictions were achieved at the seven-leaf stage of corn growth, and as early as the five-leaf stage. Both the most profitable nitrogen rate and the likely yield response to nitrogen could be predicted from the meter readings. "Predictions were best if they were based on comparison to a ‘standard’ reading taken from plants that received a high rate of nitrogen. "Management decisions tailored to a specific field can increase the profitability, and the efficiency, of the fertilizer input," Scharf said. Most corn producers in the North Central states do not apply in-season nitrogen. That may be changing. "The potential to fine-tune nitrogen rates and save fertilizer without shaving yields may lead some farmers to consider this practice. Corn producers in southeastern states, where earlyseason nitrogen loss potential is higher, often sidedress corn," Scharf said. "Meter-assisted decisions could be adopted fairly easily in that region." Hand-held meters were used in the experiments. "That may be too labor intensive for managing large corn fields," Scharf said. "However, the next generation of vehicle-mounted corn-color sensors, or aerial imagery, promise easier nitrogenmanagement decisions." Related research suggests that diagnosing and precisely meeting crop nitrogen needs will benefit water quality, as well as improve economic response. The field experiments were conducted in Illinois, Kansas, Michigan, Minnesota, Missouri, Nebraska and Wisconsin. Source: Peter Scharf (573) 882-0777. Scharf is a member of the MU Extension plant sciences group. Duane Dailey Senior Writer Extension & Ag Information University of Missouri (573) 882-9181 daileyd@missouri.edu ********************************************************************* Article 5 of 5 June 9, 2006 Weather data for the Week Ending June 5, 2006 By Pat Guinan Weather Data for the Weekly Period May 16, 2006 - May 22, 2006 -------------------------------------------------------------------------------- | Monthly | Growing Weekly Temperature (deg. F) |Precip (in.)|Degree Days^ -----------------------------|------------|------------ Ext- Ext- Depart| Depart|Accum Depart Avg.Avg. reme reme from |May 1 from |since from Station County Max.Min. High Low Mean avg. |May 31 avg. |Apr 1 avg. ------------------------------------------------------|------------|------------ Corning Atchison 84 64 89 60 74 +7 | 1.95 -2.49 | 898 +336 St. Joseph Buchanan 83 63 88 61 73 +6 | 1.66 -3.21 | 851 +249 Brunswick Chariton 82 62 88 57 72 +4 | 5.37 +0.10 | 886 +259 Albany Gentry 84 60 88 54 72 +5 | 1.07 -3.65 | 782 +200 Auxvasse Audrain 82 61 86 57 71 +3 | 2.92 -2.03 | 860 +237 Columbia Boone 82 62 85 57 71 +3 | 2.46 -2.54 | 879 +207 Sanborn Field Boone 82 63 86 60 72 +3 | 2.47 -2.59 | 965 +271 Novelty Knox 81 61 87 57 70 +3 | 2.57 -2.3 | 759 +160 Linneus Linn 82 60 88 56 71 +4 | 2.46 -2.54 | 783 +208 Monroe City Monroe 81 61 86 56 71 +3 | 1.30 -3.69 | 802 +171 Versailles Morgon 82 62 87 58 72 +4 | 2.67 -2.52 | 952 +223 Green Ridge Pettis 82 61 87 57 71 +4 | 0.74 -4.84 | 905 +309 Lamar Barton 83 61 86 55 71 +2 | 5.49 -0.23 | 1004 +254 Cook Station Crawford 83 58 85 51 69 +0 | 4.52 -0.32 | 862 +104 Alley Spring Shannon 83 59 87 51 69 +1 | 8.99 +4.05 | 866 +168 Round Spring Shannon 84 59 88 51 69 +1 | 6.88 +1.94 | 870 +172 Delta Cape | | Girardeau 85 62 88 55 73 +1 | 5.32 +0.43 | 969 + 84 Cardwell Dunklin 87 67 89 62 75 +1 | 2.72 -2.5 | 1228 +218 Clarkton Dunklin 87 65 89 57 75 +1 | 4.46 +0.1 | 1132 +144 Glennonville Dunklin 87 65 89 59 75 +1 | 3.41 -0.78 | 1137 +152 Charleston Mississippi 84 64 89 58 74 +2 | 6.72 +2.03 | 1053 +194 Portageville- | | Delta Center Pemiscot 86 67 90 63 76 +3 | 4.87 +0.16 | 1189 +210 Portageville- | | Lee Farm Pemiscot 87 67 90 62 76 +3 | 5.44 +0.69 | 1196 +229 Steele Pemiscot 87 68 89 63 76 +2 | 5.00 -0.19 | 1266 +282 -------------------------------------------------------------------------------- ^Growing degree days are calculated by subtracting a 50 degree (Fahrenheit) base temperature from the average daily temperature. Thus, if the average temperature for the day is 75 degrees, then 25 growing degree days will have been accumulated. -------------------------------------------------------------------------------- Pat Guinan, Commercial Agriculture Program (573) 882-5908