Integrated Pest and Crop Management Newsletter Vol. 16, No. 19 November 17, 2006 Final Update on Soybean Rust in Missouri for 2006 By Laura Sweets Missouri did participate in the Soybean Rust Sentinel Plot Program during the 2006 season. Twentyfour sentinel plots were distributed throughout the soybean production areas of the state. Samples of 100 terminal leaflets were submitted on a regular basis throughout the growing season to the lab at the University of Missouri. The leaflets were microscopically examined for the presence of soybean rust pustules. Until quite late in the season all of the samples submitted from the 24 sentinel plots were negative for soybean rust. By early October many of the original sentinel plots were either mature or the fields had been harvested. Sentinel plot scouts tried to locate adjacent fields that still had green leaves on plants to continue submitting samples from their counties. In early October, soybean rust was confirmed in several counties in western Kentucky. Sentinel plot scouts were asked to make one last survey of their areas to sample any fields which still had either green plants or green leaves on scattered plants in fields. As a result of this end of the season survey soybean rust was found in five Missouri counties, Pemiscot, New Madrid, Scott, Stoddard and Mississippi counties. The hypothesis is that the front, which moved up from the southeastern US over September 21-23, may have deposited soybean rust spores in the southeastern area of Missouri as well as western Kentucky and Tennessee and other states along the Ohio River Valley. For Missouri these soybean rust detections were so late in the season that soybean rust had no impact on yield. Most of the samples submitted that were positive had only one or two infected leaflets in the 100 leaflet sample and the number of pustules per leaflet was also quite low. Across the United States for the 2006 season, soybean rust was confirmed on soybeans in 230 different counties in 15 states and (see USDA Public PIPE Website at www.sbrusa.net; figure below) for exact locations by state. When reports of soybean rust on kudzu are combined with the reports from soybean, soybean rust was confirmed in a total of 262 counties in 15 states during the 2006 season. Rust levels may have been severe enough to have impacted yield in some of the southern states. And research results from fungicide trials, yield loss trials, spore trap studies should be available in the near future from some southern states. For most states in the Midwest, the rust infections came in late enough in the season that yield was not affected and research trials will not have meaningful results related directly to soybean rust. Laura Sweets 573-884-7307 ********************* Herbicide Options for Weed Management in Winter Wheat By Kevin Bradley Henbit, wild garlic, cheat, downy brome, shepherd’spurse, field pennycress, wild garlic and a variety of mustard species are some of the most common winter annual weeds encountered in wheat production in Missouri. Some of these species are not very competitive with wheat, and may only justify treatment when present at fairly high densities. For example, research conducted in Missouri has revealed that it takes as many as 82 henbit plants per square meter before even minor yield reductions are incurred in wheat. Other researchers have found that it researchers have found that it takes even higher henbit densities before wheat yield losses will occur. Based on our observations, it seems likely that shepherd’s-purse and some of the mustard species also fall into this category of weeds that are not very competitive with wheat. On the other hand, common chickweed, cheat and downy brome are some of the winter annual weeds that will cause yield reductions and the presence of these species almost always justifies treatment. Research indicates that common chickweed can cause significant yield losses at densities of at least 30 plants per square meter while 80 cheat plants per square meter have resulted in yield losses as high as 50 percent. Another species that must also be controlled is wild garlic, not necessarily because it will cause wheat yield reductions, but because the aerial bulblets of this weed will contaminate the wheat grain at harvest and can cause significant dockage at the grain bin. One of the most common (and effective) herbicides utilized for weed control in wheat is Harmony Extra. Harmony Extra controls most of the broadleaf weeds that we encounter in wheat including henbit, field pennycress, shepherd’s-purse, common chickweed and several mustard species. Additionally, Harmony Extra will provide suppression of wild garlic to the point that the aerial bulblets of this weed will not be produced. Perhaps the most significant weakness of Harmony Extra is that it does not have any grass activity and therefore does not control cheat and downy brome, two of our most troublesome winter annual grasses. Harmony Extra can be applied from the two-leaf up to the flag leaf stage of wheat. Another herbicide that is commonly utilized for broadleaf weed control in wheat is 2, 4-D. This is one of our cheapest options for broadleaf weed control in wheat, but like Harmony Extra, this herbicide has no activity on grasses. It is very important for applications of 2, 4-D and all other growthregulating herbicides (Banvel, Clarity, MCPA) to be made after tillering, but before the jointing stage of wheat or severe crop injury can occur. Jointing is a wheat stage that precedes stem elongation and can be determined by feeling the plant for the presence of a ‘joint’ just above the soil surface. You can do this by pinching the existing wheat stem and sliding your fingers upwards from the base of the plant. If a hard bump is felt about an inch or so above the soil surface, slicing into this area will more than likely reveal the presence of a joint, or node, and 2, 4-D applications at this time should be avoided. Research conducted in Missouri has revealed that yield losses as high as 6 bushels per acre can occur if 2, 4-D applications are made to wheat that is in the jointing stage of growth. Both amine and ester formulations of 2, 4-D are available, but the ester formulation of 2, 4-D is usually more effective at breaking through the cuticle of tough weeds like wild garlic. In addition to Harmony Extra and the growth-regulator herbicides, Sencor is another option that is perhaps less-often utilized for weed control in wheat, most likely due to the sensitivity of many wheat varieties to this herbicide. Sencor has historically been one of the few options that we had for downy brome and cheat control in Missouri. Sencor may be applied during tillering but before jointing occurs. In addition to cheat and downy brome, Sencor also provides good control of many of our common winter annual broadleaf weeds like common chickweed, field pennycress and henbit. Prior to making a Sencor application, you should always check the label and/or contact your Bayer representative regarding the sensitivity of your wheat variety to this herbicide. Several growers have contacted me recently regarding some of the newer wheat herbicides that have been registered over the past couple of years in Missouri. Some of these include Olympus, Olympus Flex and Osprey. All are products from Bayer CropScience and are ALS-inhibiting herbicides. Olympus was one of the first products of the three from Bayer to be introduced and has good activity on several winter annual grasses including cheat and downy brome, and also on some winter annual broadleaf weeds like shepherd’s-purse, field pennycress and certain mustards. Although Olympus will provide good control of downy brome and cheat, the crop rotational restrictions may limit the use of this product for growers who wish to double-crop soybeans following wheat or even for growers who wish to rotate to corn the next season. For example, corn may not be planted for 18 months after an Olympus application while conventional or Roundup Ready® soybeans may not be planted for 12 months after Olympus applications. STS soybeans, however, may be planted four months after an Olympus application, which allows wheat growers to make a fall application and plant double-crop STS soybeans after wheat harvest. In order to resolve the issue of crop rotational flexibility, Bayer developed a new product called Olympus Flex, which contains the active ingredient in Olympus along with the active ingredient in Osprey. Olympus Flex can be applied from wheat emergence up to jointing and provides relatively good control of many of the Bromus spp., as well as Italian or annual ryegrass and several key winter annual broadleaf weeds like shepherd’spurse, field pennycress, and certain mustards. Soybeans may be planted five months after an Olympus Flex application while the rotational interval for corn following an Olympus Flex application is 12 months. Osprey is another relatively new herbicide from Bayer CropScience that may be applied to wheat up to the jointing stage of growth. Osprey provides excellent control of Italian or annual ryegrass, which appears to be a problem for some producers in the southern portion of Missouri, but is not yet a state-wide problem in wheat as it is in many other portions of the U.S. As Osprey is an ALS-inhibiting herbicide, it is particularly effective in controlling Hoelon-resistant Italian ryegrass populations that have developed in these other areas. Osprey also provides some suppression of downy brome and cheat, but generally less control of these species than what is considered “commercially acceptable” and less than that provided by Olympus Flex. Soybeans may be planted three months after an Osprey application while the rotational interval for corn following an Osprey application is 12 months. Kevin Bradley 573-882-4039 ********************* New Aeration Tool on Horizon Uses Air Conditions By Bill Casady There’s a new tool available to help plan when to run the fan for drying and cooling grain for long-term storage. The tool predicts air temperature and relative humidity and includes the corresponding equilibrium moisture content for corn or soybeans for the predicted air conditions. Equilibrium moisture content is the moisture content that would be reached if the grain was exposed to the given temperature and humidity for a long period of time. To find the new tool, go to the AgEbb website at http://agebb.missouri.edu, click on ‘Missouri Agricultural Weather’ then on ‘Horizon Point’ or go directly to http://agebb.missouri.edu/horizonpoint/. Horizon Point provides a wealth of weatherrelated information, providing both historical and predicted precipitation and temperature data, a wind forecast, estimated rainfall that might cause runoff based on your soil type, cattle and poultry stress indices, seasonal items such as spring planting soil temperature charts, weed scouting aids, and links to other information. The information available via Horizon Point will only continue to grow as new tools are developed. November and December are often an excellent time to plan your last cooling period for grain stored for the long-term. For example, the average temperature in a recent Horizon Point e-mail report for my location is somewhere between 28 and 43 degrees. Add a couple of degrees for the natural rise in temperature of the air from the fan motor and grain aerated during this period will reach an average temperature of maybe 37 or 38 degrees F. We always recommend that the last cooling cycle should bring the temperature of the grain down to about 35 degrees. As I scan the report, I also note that equilibrium moisture contents for corn throughout the day are 16.5, 17.8, 18.5, 17.3, 14.7, 13.5, 16.8 and 17.4 percent. I can rest assured that little or no drying of corn will occur since the average equilibrium moisture content for corn for the current report is well above 15.5 percent. If I know the grain is already plenty dry, I’m probably going to run the fan now to do some cooling. No significant re-wetting is likely to occur. If moisture content is still above 15.5 percent and I want to dry the grain a little more, I may wait for a day when those equilibrium moisture contents are below 15.5 percent on the average or I may run the fan intermittently, probably during the afternoons, when the air is typically drier. I’ll just keep watching my e-mail reports for the day that suits my needs best. More information about the significance of the properties of ambient air in drying or cooling grain is available at http://ag3.agebb.missouri.edu/horizonpoint/examplereports/report_m_mor e.asp. Your first Horizon Point reports may take a couple of weeks to arrive, but then will reach you regularly at the intervals you specify, so sign up now for your Horizon Point e-mail reports. Then when spring planting is on the horizon, Horizon Point will also provide you with soil temperature information and weed scouting aids. My final note is to ask you to stay safe when inspecting grain bins and moving grain. If you have any questions about the safety of a particular situation, call me and talk it over before dealing with a bin that may have spoiled grain. Bill Casady 573 882-4370 ********************* Weather data for the Week Ending November 14, 2006 By Pat Guinan -------------------------------------------------------------------------------- | Monthly | Growing Weekly Temperature (deg. F) |Precip (in.)|Degree Days^ -----------------------------|------------|------------ Ext- Ext- Depart| Depart|Accum Depart Avg.Avg. reme reme from |Nov 1 from |since from Station County Max.Min. High Low Mean avg. |Nov 14 avg |Apr 1 avg. ------------------------------------------------------|------------|------------ Corning Atchison 58 36 81 21 47 +6 | 0.12 -1.07 | 3880 +552 St. Joseph Buchanan 57 37 79 26 47 +5 | 0.06 -0.87 | 3803 +389 Brunswick Chariton 58 34 77 27 47 +3 | 0.18 -1.20 | 3795 +313 Albany Gentry 57 35 79 24 45 +4 | 0.08 -1.11 | 3577 +185 Auxvasse Audrain 59 36 76 26 47 +3 | 0.77 -0.94 | 3768 +263 Columbia Boone 59 38 76 27 48 +3 | 0.59 -0.78 | 3903 +234 Sanborn Field Boone 59 38 76 28 49 +3 | 0.44 -0.94 | 4159 +403 Williamsburg Callaway 60 36 78 25 48 +4 | 0.60 -1.11 | * * Novelty Knox 54 35 74 26 44 +1 | 0.62 -0.98 | 3493 +71 Linneus Linn 58 35 76 24 46 +4 | 0.15 -1.17 | 3562 +239 Monroe City Monroe 57 34 74 25 45 +2 | 0.63 -0.94 | 3630 +137 Versailles Morgon 62 40 81 29 50 +3 | 0.34 -1.19 | 4213 +456 Green Ridge Pettis 61 37 78 27 49 +5 | 0.47 -1.12 | 4057 +607 Lamar Barton 64 38 83 28 51 +4 | 0.34 -1.41 | 4226 +275 Cook Station Crawford 64 33 86 20 49 +2 | 1.88 -0.03 | 3699 -102 Alley Spring Shannon 64 33 83 19 47 +1 | 1.83 +0.00 | 3544 -58 Round Spring Shannon 64 33 83 20 47 +1 | 1.42 -0.41 | 3552 -50 Delta Cape | | Girardeau 60 37 77 28 49 +1 | 1.88 +0.12 | 3934 -237 Cardwell Dunklin 61 40 76 30 52 +2 | 2.29 +0.85 | 4508 -26 Clarkton Dunklin 61 39 78 29 51 +2 | 2.13 +0.42 | 4403 -73 Glennonville Dunklin 61 41 79 29 52 +3 | 1.92 +0.19 | 4369 -79 Charleston Mississippi 60 39 76 33 50 +2 | 1.25 -0.16 | 4244 +128 Portageville- | | Delta Center Pemiscot 61 42 77 31 52 +3 | 1.87 +0.26 | 4575 +125 Portageville- | | Lee Farm Pemiscot 62 41 79 32 52 +3 | 1.91 +0.34 | 4586 +168 Steele Pemiscot 62 42 77 32 53 +3 | 2.62 +1.15 | 4692 +280 -------------------------------------------------------------------------------- * Complete data not available for report ^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