Integrated Pest & Crop Management Newsletter University of Missouri-Columbia Vol. 16, No. 1 January 20, 2006 Soybean Rust Update By Laura Sweets During the 2005 season soybean rust was not detected on soybean, kudzu or any other host plant in Missouri. Soybean rust was reported from nine states during the 2005 season primarily on either soybean or kudzu. A summary of the positive reports is as follows: State Number of counties with positive reports of soybean rust Alabama 33 Florida 23 Georgia 35 Louisiana 2 Mississippi 2 North Carolina 18 South Carolina 23 Texas 1 Kentucky 1 The Texas and Kentucky reports came in late in the season and were both on kudzu. A brief comparison between the falls of 2004 and 2005 may help explain why soybean rust was found late in the season on plants in fields in Pemiscot and New Madrid Counties in Missouri in 2004 but was not found in 2005. Fall Conditions: 2004 vs 2005 Fall 2004 Fall 2005 Unusually wet Unusually dry Mild, <28 degrees F by Dec. 14 Cold earlier than normal, <28 degrees F by Nov. 17 (14 degrees F in Columbia on Nov.17) Nov. 6, 2004 ~ 67 percent Nov. 6, 2005 ~91 percent soybean crop harvested soybean crop harvested The positive reports in Missouri in 2004 were from scattered green plants in fields that had not been harvested due to wet conditions. By early to mid- November 2005, most soybean fields in the state had been harvested and surveys to detect any late season infections of soybean rust were unsuccessful. Drs. Robert Kemerait, Philip Jost and Layla Sconyers of the University of Georgia, had an excellent article entitled "Looking Back at Soybean Rust in the 2005 Season" in their Soybean Newsletter dated December 7, 2005. A summary of main points from that article would be that the initial find of soybean rust on volunteer soybeans in Seminole County in late April did not have any real impact on the 2005 soybean crop. The major, sustained outbreak of soybean rust was first detected in southwest Georgia in mid- July. This outbreak continued to spread across the state and by the end of the season was found in counties bordering Florida, Alabama, South Carolina and Tennessee. The movement of the disease within the state was relatively slow. An estimate of the rate of movement from the Tift County site to Oconee County was approximately 60 miles per day. The number of days between first observation of initial rust pustules on leaves using a microscope to examine the leaves and symptoms in the field that would be apparent from typical scouting and examination of leaves with a hand lens was a number of weeks. Fungicide trials did show benefits from properly timed applications of triazoles, strobilurins and triazole-strobilurin mixes. The question now is how well will the soybean rust pathogen overwinter on hosts such as kudzu, how far north will it overwinter and what can we expect in 2006? The fungus that causes soybean rust, Phakopsora pachyrhizi, is an obligate parasite so survives on living plant tissue. The period of December 2004 through January 2005 was unusually cold in the southeastern United States. The accompanying maps show the 28 degrees or moderate frost line for the Gulf Coast states during that time period. The unusually low temperatures may have reduced the overwintering level of soybean rust by killing back perennial hosts such as kudzu to a greater extent than normal. Unfortunately parts of the southeastern United States have not experienced these moderate frost levels this winter. See accompanying maps below. Folks in the southern United States have not taken a break from soybean rust scouting. Scouting primarily of kudzu but also of volunteer soybeans has continued through December and into January. Results so far from southern states include: Texas December 22, 2005: rust-infected kudzu patch near (Dr. Tom Dayton, TX was scouted. Patch had died back ~90% but Isakeit) still had a few green leaves loaded with rust pustules. Alabama December 20 and 21, 2005: Green, rust-infected kudzu (Dr. Ed near Evergreen, AL; two rust-infected patches that were Sikora) barely hanging on in Baldwin County, AL; and a sizeable semi-green, rust-infected patch of kudzu in Clark County, AL. January 12, 2006: Soybean rust detected on two kudzu patches in the city of Montgomery, AL. Most of the two patches were dormant, but the remaining green foliage was infected with soybean rust. Georgia January 11, 2006: Fourteen county survey found kudzu (Dr. Layla 99-100% dead although at a few locations new buds were Sconyers) beginning to form on some vines. Florida January 10, 2006: Kudzu in a culvert facing south located (Drs. Jim near Quincy, FL was developing new leaves and one Marois, Glen rust-infected leaf was found. Hartman and Scott Isard) January 11-13, 2006: A survey of all kudzu patches that were reported positive for soybean rust in 2005 (that could be located again) found seven of thirteen sites positive for rust in 2006. One additional rust-infected kudzu site was also found. Most sites had appreciable dieback but a few sites in the south had little dieback. Active soybean rust pustules are being found on kudzu in scattered locations in the southeastern UnitedStates. Current levels seem quite low but it will be important to see how this develops over the next few months. The bottom line still remains that in order for soybean rust to develop and cause significant damage to soybeans in Missouri, the pathogen must overwinter in the south, that inoculum must be moved or transported up to the Midwest and weather conditions in Missouris during the growing season must be favorable for disease development. For 2006 it is important for soybean producers in Missouri to be aware of disease development and weather patterns in the southern United States; to scout fields and be aware of results from the sentinel plot system in southern states, states close to Missouri and in Missouri; and to be prepared to take prompt action if a risk of soybean rust develops. Laura Sweets Ag Ext-Plant Sciences 573-884-7307 ******** Soybean Seed Treatment Fungicides By Laura Sweets Soybean seed treatment fungicides can be effective in preventing or reducing damage from pathogens that may be carried on the seed or pathogens present in the soil that cause seed decay, seedling blights and root rots of soybean. Soybean seed treatment fungicides are recommended if there is a concern about seed-borne diseases (ex. Phomopsis seed decay), if the field has a history of a specific early-season soybean disease (ex. field has a history of Phytophthora root rot) or conditions at planting are not favorable for rapid germination and emergence thus favoring early-season soybean diseases (ex. cold and wet soils might favor Pythium seed decay and seedling blight). Soybean seed treatment fungicides will not improve the germination of seed that has a poor germination rate because of physical cracks in the seed coat, weathering during the seed production year and other physiological factors. A number of products are labeled for use on soybean seed. Basically these products can be divided into fungicides that are effective against the water mold fungi Pythium and Phytophthora or those effective against fungi other than Pythium and Phytophthora, i.e. Rhizoctonia, Fusarium, Macrophomina and other soil or seed-borne fungi. Metalaxyl and mefenoxam are labeled for use against Pythium and Phytophthora. These active ingredients are available alone or in combination with other soybean seed treatment fungicides. Azoxystrobin, captan, carboxin, fludioxonil, PCNB, TBZ (thiabendazole) and thiram are labeled for use against fungi other than Pythium and Phytophthora. These active ingredients are available alone, in combinations or in combination with products effective against Pythium and Phytophthora. The following tables lists soybean seed treatment fungicides by active ingredients and is divided into products effective against water mold fungi, products effective against fungi other than water molds and products that contain both types of soybean seed treatment fungicides. As with many agricultural businesses, the fungicide seed treatment industries have gone through several mergers and acquisitions. I have tried to make this list as comprehensive and current as possible; however, label registrations and products can change at any time. Before using any agricultural pesticide, read and follow directions on the label accompanying that product. Product names have been used for clarity. Reference to specific trade names does not imply endorsement of these products by the University of Missouri; discrimination is not intended against similar products not listed. Federal Law requires that bags containing treated seeds shall be labeled with the following information: "This seed has been treated with (common chemical names of active ingredients) fungicide(s). Do not use treated seed for food, feed or oil purposes." Soybean Seed Treatment Fungicides Effective Against Pythium and Phytophthora ________________________________________________________________________________ Active Ingredient Examples of Product Trade Names (Company) metalaxyl Allegiance Dry (Trace Chemicals LLC) Allegiance-FL (Gustafson LLC) Allegiance-LS (Gustafson LLC) mefenoxam Apron XL LS (Syngenta) ________________________________________________________________________________ ________________________________________________________________________________ Soybean Seed Treatment Fungicides Effective Against Fungi Other Than Pythium and Phytophthora Active Ingredient Examples of Product Trade Names (Company) azoxystrobin Protege FL (Gustafson LLC) captan Bean Guard (Trace Chemicals LLC.) Captan 30-DD (Gustafson LLC) Captan 400 (Gustafson LLC) Captan 400 C (Gustafson LLC) Enhance (Trace Chemicals LLC) HiMoly/Captan-D (Trace Chemicals LLC) Rival Flowable (Gustafson LLC) Vitavax M DC (Helena) carboxin Bean Guard (Trace Chemicals LLC) Enhance (Trace Chemicals LLC) Kernel Guard Supreme (Trace Chemicals LLC) RTU-Vitavax-Thiram (Gustafson LLC) Vitaflo-280 (Gustafson LLC) Vitavax CT (Helena) Vitavax M DC (Helena) Vitavax M (Helena) Vitavax-PCNB (Gustafson LLC) Vitavax T-L (Trace Chemicals LLC) Vitavax-200 (Gustafson LLC) Vitavax-34 (Gustafson LLC) fludioxonil Maxim 4FS (Syngenta) PCNB Rival Flowable (Gustafson LLC) RTU-PCNB (Gustafson LLC) Vitavax-PCNB (Gustafson LLC) TBZ (thiabendazole) LSP (Gustafson LLC) Rival Flowable (Gustafson LLC) RTU Flowable (Gustafson LLC) thiram Protector-D (Trace Chemicals LLC) Protector-L (Trace Chemicals LLC) RTU Flowable (Gustafson LLC) RTU-Vitavax-Thiram (Gustafson LLC) Triple Noctin L (Trace Chemicals LLC) 42-S Thiram (Gustafson LLC) Vitaflo-280 (Gustafson LLC) Vitavax CT (Helena) Vitavax M (Helena) Vitavax T-L (Trace Chemicals LLC) Vitavax-200 (Gustafson LLC) _________________________________________________________________________ _________________________________________________________________________ Active Ingredient Examples of Product Trade Names (Company) azoxystrobin SoyGard (Gustafson LLC) + metalaxyl captan + carboxin Bean Guard Allegiance (Trace Chemicals LLC) + metalaxyl captan + PCNB Rival Pak (Gustafson LLC) + thiabendazole + metalaxyl carboxin + PCNB Prevail (Trace Chemicals LLC) + metalaxyl carboxin + thiram Stiletto (Trace Chemicals LLC) + metalaxyl Stiletto Pak (Trace Chemicals LLC) chloroneb + mefenoxam Catapult XL (Agriliance, LLC) Delta Coat XL (Agriliance, LLC) chloroneb + metalaxyl Catapult (Agriliance, LLC) Delta-Coat AD (Agriliance) fludioxonil Maxim 4FS (Syngenta) mefenoxam ApronMAXX RFC (Syngenta) + fludioxonil ApronMAXX RTA (Syngenta) ApronMAXX RTA + moly (Syngenta) Maxim XL (Syngenta) Warden RTA (Agriliance) thiram + metalaxyl Protector-L-Allegiance (Trace Chemicals LLC) _______________________________________________________________________ Laura Sweets Ag Ext-Plant Sciences 573-884-7307 ******** Fed hay can be an import fertilizer for pastures By John Lory High fertilizer costs make it imperative that cattle producers maximize the benefits of all fertilizer sources on their farm. Often farmers overlook the fertilizer value of fed hay. A ton of fescue hay contains approximately 40 pounds of nitrogen, 15 pounds phosphate and 40 pounds potash. Many of those nutrients pass through the cattle; non-lactating cows return the equivalent of almost all fed nutrients back to pasture. Some of the nitrogen is lost so ultimately approximately 25% of the fed nitrogen and all the fed phosphate and potash have fertilizer value. The nutrients in a ton of hay are enough to match the phosphate and potash nutrient removal rates for one acre of pasture. Fertilizer value of nutrients in a ton of hay is about $15 assuming $0.40 for nitrogen, $0.30 for phosphate and $0.20 for potash. This source of fertilizer only has value if your manure spreader, the cow, does a good job of distributing its manure around a field. Cattle naturally tend to deposit most of their manure near feeders and water sources in a pasture. The following practices help improve the distribution of manure in pastures: *Spread the wealth! Frequently move feeders and feeding areas around the pasture. *Increase the stocking density of animals but move animals from area to area more frequently to prevent over use of areas in the pasture. *Do not use the same pastures for supplemental feeding every year but move winter feeding areas each year to distribute the nutrient benefits around the farm. To protect water quality, maintain a setback area between winter feeding areas and streams and lakes. Frozen and saturated soil promotes the movement of manure nutrients in runoff. Nutrient losses in runoff will have little impact on the fertilizer value of manure but can have a big impact on stream and lake water quality. John Lory Commercial Agriculture Program and Division of Plant Science ******** National Alfalfa Alliance presents Alfalfa Intensive Training Seminar March 7-9, 2006 Hilton St. Louis Airport For more information go to www.alfalfa.org or call 509-585-6798 ******** Planting Soybean Resistant to Soybean Cyst Nematode is a Widespread Practice: Should Producers Still Send in Soil Samples? By Robert Heinz, Coordinator, MU Extension Nematology Lab, Dr. Laura Sweets, Soybean Extension Pathologist, and Dr. Melissa G. Mitchum, Nematologist Over the course of the past 10 years there has been a steady increase in the use of soybean cyst nematode (SCN) resistant cultivars by Missouri soybean producers to manage SCN. The availability and use of SCN resistant lines has led many soybean producers to believe that SCN is no longer a major cause of yield loss. As a result, this has led to a significant decline in the number of farmers who regularly monitor their fields for SCN. SCN, however, continues to be the number one pathogen on soybean and contributes to nearly $1 billion in soybean yield losses in the US annually. The reality is that over 90% of the SCN resistant soybean lines grown in Missouri derive their resistance from one source, Plant Introduction (PI) 88788. Continuous cropping of soybean lines with SCN resistance derived from the same genetic source has the potential for losing effectiveness when combined with genetically variable SCN field populations. This type of management practice decreases the durability of current sources of resistance by selecting for nematode populations that increase well on resistant soybean lines. To maintain the durability of existing sources of resistance for effective long-term management of SCN, an integrated approach incorporating crop rotation (through the use of resistant soybean and non-host crops) and regular monitoring of SCN field populations by producers is absolutely necessary. In this study, collaborating MU Extension Agronomists located across Missouri soybean producing regions requested soil samples from soybean producers that met one or more of the following criteria: 1) producers who are not using SCN resistant varieties 2) producers who are continuously cropping SCN resistant soybean 3) producers who when asked, do not believe that they have a SCN problem in their field 4) producers who have noticed a decline in yield over the past few years 5) producers who have never submitted a soil sample for SCN testing. A total of 122 soil samples were collected from 47 soybean producing counties in Missouri. Producers submitting samples were also asked to answer 3 short survey questions: 1) When was the last time you submitted soil samples for SCN testing? Never; Less than 5 years ago; More than 5 years ago 2) How many years have you been growing SCN resistant soybean lines? Never; 0-5 years; 6-10 years; over 10 years. 3) Do you think that you have suffered yield loss as a result of SCN during the last three years? No; Yes: 3-5 b/a, 5-10 b/a, more than 10 b/a. All 122 soil samples were processed for an SCN egg count. Twenty samples were chosen with >5000 eggs/cup for HG Type tests (which includes the old race designation). From the 122 samples collected and processed for an egg count: 26 percent had "0" eggs/cup soil, 13 percent had a low rating (1-500 eggs/cup soil), 42 percent had a medium rating (501-10,000 eggs/cup soil), 19 percent had a high rating (>10,000 eggs/cup soil) (Figure 1). When producers were surveyed about whether they thought they had any yield loss over the last three years because of SCN: 62 percent said no loss of yield, 16 percent said 3-5 bushels/acre, 12 percent said 5-10 bushels/acre, 2 percent said more than 10 bushels/acre, 8 percent said they don’t know (Figure 2). Astonishingly, 61 percent of the producers had egg counts above the damage threshold, yet 62 percent of them did not believe they had any yield loss due to SCN. The survey indicated that only 8 percent of soybean producers have never grown SCN-resistant soybeans, and 7 percent were not sure. This means that between 85 - 92 percent of the farmers are currently planting SCN-resistant soybeans. Most of these producers have been planting SCN-resistant soybeans from five to 15 years (Figure 3). In fact, some bootheel farmers have been growing SCN-resistant lines for 20 to 30 years. Based on the survey responses and results of the egg count assays, it appears that soybean producers are assuming that any yield loss suffered is due to factors other than SCN because they are planting SCN-resistant soybean cultivars. When soybean producers were asked when they last sent in a soil sample to monitor for SCN, 64 percent indicated that they have never sent in a sample. Of the 36 percent who had sent in soil samples to test for SCN, only 6 percent of the producers had sent in a sample for SCN within the last 5 years, however, 25 percent had sent in samples 5 or more years ago (Figure 4). This seems to indicate that SCN was considered a problem in the past, but is not seen as a "yield-reducer" today. This is likely because many producers today are under the false assumption that SCN-resistant soybean lines have eliminated the SCN problem. The data from the 20 HG Type tests conducted in this project also seemed to confirm the fact that 90% of the resistant lines grown in Missouri derive from PI 88788 (complete test results at http://soilplantlab. missouri.edu/nematode/scnreport05.htm). Our study indicates that this source of resistance is not holding up well against existing SCN field populations. Of the 20 tests, 85 percent showed an increase of greater than 10 percent on PI 88788. Sixty percent of the tests showed an increase greater than 25 percent on PI 88788. The highest test increased on PI 88788 by 80 percent (the lowest, 4 percent). The average of all 20 tests showed an increase of 33 percent on PI 88788. Although one must be careful in generalizing from only 20 tests, this study clearly indicates that it would be wise for soybean producers in Missouri to monitor their fields for SCN by sending in a soil sample to the MU Extension Nematology Lab (instructions at http://soilplantlab.missouri.edu/nematode/) for an egg count every 2 to 3 years. If the egg count is above the damage threshold of 500 eggs/cup, but below 10,000 eggs/cup, consider planting and rotating SCN-resistant soybeans. When the egg count exceeds 10,000 eggs/cup, producers should consider rotation with a nonhost crop (e.g., corn) and/or have an HG Type (Race Test) run on a soil sample to determine which HG Type or race of SCN exists in their field. The results of this test will help the producer determine what sources of resistance would be good to manage the SCN population in their field. Resistant soybean lines should be sought that have varied sources of resistance. This is not an easy task because most varieties sold in Missouri derive resistance from PI 88788. Soybean producers should be aware of the source of SCN resistance in the soybean they are planting. Soil samples may be sent to the Extension Nematology Lab, Mumford Hall, Rm 23, Columbia, MO 65211. For questions, contact Bob Heinz at 573-884-9118. Robert Heinz, Coordinator, MU Extension Nematology Lab, Dr. Laura Sweets, Soybean Extension Pathologist, and Dr. Melissa G. Mitchum, Nematologist ******** Weather Data for the Week Ending January 17, 2006 By Pat Guinan -------------------------------------------------------------------------------- | Monthly | Growing Weekly Temperature (deg. F) |Precip (in.)|Degree Days^ -----------------------------|------------|------------ Ext- Ext- Depart| Depart|Accum Deprt Avg.Avg. reme reme from |Jan 1- from |since from Station County Max.Min. High Low Mean avg. |Jan 17 avg. |Apr 1 avg ------------------------------------------------------|------------|------------ Corning Atchison 51 26 63 18 39 +15 | 0.00 -0.52| * * St. Joseph Buchanan 49 29 62 22 39 +13 | 0.00 -0.33| * * Brunswick Chariton 50 26 64 16 38 +12 | 0.30 -0.34| * * Albany Gentry 47 24 61 17 36 +11 | 0.45 -0.06| * * Auxvasse Audrain 52 30 61 21 39 +13 | 0.88 +0.10| * * Columbia Boone 52 30 62 22 40 +12 | 0.96 +0.19| * * Sanborn Field Boone 53 32 63 25 41 +13 | 0.81 +0.03| * * Novelty Knox 48 28 61 21 37 +12 | 0.72 +0.14| * * Linneus Linn 48 28 61 17 37 +12 | 0.77 +0.33| * * Monroe City Monroe 50 30 60 20 39 +13 | 0.49 -0.14| * * Versailles Morgan 55 31 66 23 42 +12 | 0.50 -0.29| * * Green Ridge Pettis 53 29 65 19 41 +13 | 0.15 -0.55| * * Lamar Barton 55 31 66 21 43 +12 | 0.37 -0.48| * * Cook Station Crawford 55 31 64 23 42 +10 | 0.89 -0.27| * * Alley Spring Shannon 55 25 62 19 39 +7 | 1.37 +0.21| * * Round Spring Shannon 55 26 63 20 39 +7 | 1.48 +0.32| * * Delta Cape | | Girardeau 52 32 57 29 41 +10 | 2.69 +1.34| * * Cardwell Dunklin 54 34 60 30 43 +9 | 2.35 +0.72| * * Clarkton Dunklin 54 33 58 28 42 +9 | 2.49 +0.96| * * Glennonville Dunklin 55 34 61 29 43 +10 | 1.84 +0.33| * * Charleston Mississippi 53 32 60 28 42 +11 | 2.71 +1.12| * * Portageville- | | Delta Center Pemiscot 54 35 59 31 43 +10 | 3.14 +1.46| * * Portageville- | | Lee Farm Pemiscot 55 35 60 31 44 +11 | 3.48 +1.82| * * Steele Pemiscot 54 35 60 31 43 +9 | 2.33 +0.79| * * -------------------------------------------------------------------------------- * 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