The importance of fungicide seed treatments on cotton was examined using a series of standardized fungicide trials from 1993 to 2004. Fungicide seed treatments increased stands over those from seed not treated with fungicides in 119 of 211 trials. Metalaxyl increased stands compared to nontreated seed in 40 of 119 trials having significant fungicide responses, demonstrating the importance of Pythium spp. on stand establishment. Similarly, PCNB seed treatment increased stands compared to nontreated seed for 44 of 119 trials with a significant response, indicating the importance of Rhizoctonia solani in stand losses. Benefits from the use of newer seed treatment chemistries, azoxystrobin and triazoles, were demonstrated by comparison with a historic standard seed treatment, carboxin + PCNB + metalaxyl. Little to no stand improvement was found when minimal soil temperatures averaged 25°C the first 3 days after planting. Stand losses due to seedling pathogens increased dramatically as minimal soil temperatures decreased to 12°C and rainfall increased. The importance of Pythium increased dramatically as minimal soil temperature decreased and rainfall increased, while the importance of R. solani was not affected greatly by planting environment. These multi-year data support the widespread use of seed treatment fungicides for the control of the seedling disease complex on cotton.

Cotton and snap bean were selected for a multi-year, multi-state regional (south-eastern USA) research project to evaluate the efficacy of both commercial and experimental bacterial and fungal biological control agents for the management of damping-off diseases. The goal for this portion of the project was to determine the viability and stability of biological agents after application to seed. The biological seed treatments used included: (1) Bacillaceae bacteria, (2) non-Bacillaceae bacteria, (3) the fungus Trichoderma and (4) the fungus Beauveria bassiana. Seed assays were conducted to evaluate the following application factors: short-term (< or = 3 months) stability after seed treatment; quality (i.e. isolate purity); compatibility with chemical pesticides and other biocontrol agents; application uniformity between years and plant species. For the bacterial treatments, the Bacillaceae genera (Bacillus and Paenibacillus) maintained the greatest population of bacteria per seed, the best viability over time and the best application uniformity across years and seed type. The non-Bacillaceae genera Burkholderia and Pseudomonas had the least viability and uniformity. Although Beauveria bassiana was only evaluated one year, the seed fungal populations were high and uniform. The seed fungal populations and uniformity for the Trichoderma isolates were more variable, except for the commercial product T-22. However, this product was contaminated with a Streptomyces isolate in both the years that it was evaluated. The study demonstrated that Bacillaceae can be mixed with Trichoderma isolates or with numerous pesticides to provide an integrated pest control/growth enhancement package.

Thirteen bacterial, four fungal, and four chemical fungicide seed treatments were evaluated one or more years in multiple field locations across the southern United States. Snap bean seed was treated in bulk with fungicides and most biocontrol agents, shipped to individual locations, and stored until planting or treated on site immediately before planting. Populations of biocontrol agents on seeds were assayed after seed treatment and planting. Analysis of variance of percent plant stand at 28 days after sowing revealed highly significant (P<0.01) effects of location and treatment in 1996, 1997 and 1998. A treatment by location interaction also occurred in 1996 and 1997. When treatments tested in two or three years were analyzed together, no biological seed treatments significantly affected percent stand. Carboxin significantly increased percent stand compared with nontreated seed in data sets combined from 1997 and 1998 and 1996 to 1998; captan and carboxin plus metalaxyl also increased stand in 1997 and 1998. Improvements in efficacy and consistency of biological seed treatments are necessary before they can be recommended for use in snap bean production.

The purpose of this study was to assess the biocontrol efficacy of the fungus Trichoderma virens in combination with fungicides against cotton (Gossypium hirsutum) seedling disease pathogens in the field under different soil and ambient environmental conditions. Cotton seed treated with fungicides and/or coated with a latex sticker and air-dried granules of T. virens was planted in field plots with a history of seedling disease in California (CA), Oklahoma (OK), Arkansas (AR), Louisiana (LA), Mississippi (MS) and Indiana (IN), and surviving seedlings counted. Seedling stands in CA from T. virens plus metalaxyl-treated seed plots were greater than the untreated control and most of the plots in which seed was treated only with fungicide. In AR and MS, T. virens plus metalaxyl treatments produced significantly better stands than the untreated controls. In some cases, this combination produced stands equal to those in fungicide-tre ated controls. In LA, OK, and IN, T. virens plus metalaxyltreated seed resulted in stands equal to those in untreated controls, but less than those in the fungicidetreated controls. The addition of triademenol or fludioxonil to the seed treatment combinations did not improve stands above T. virens plus metalaxyl alone. The treatment of cotton seed with T. virens plus metalaxyl generally resulted in greater seedling stands than those in untreated controls and equal to those of the fungicide control, except where disease pressure is very heavy (IN) or light (LA and OK).

WETZEL, M., and W. E. BATSON. 1980. Influence of polyethylene oxide seed tape on growth of Rhizoctoniasolani and Pythium aphanidermatum and on damping-off of tomato. Phytopathology 70:558-559. Seedling emergence from soil artificially infested with Rhizoctonia solani reduced on media amended with polyethylene oxide tape. No significant or Pythium aphanidermatum was greater when untreated tomato seed were differences were found in fresh or dry weights of seedlings, root-hypocotyl, placed in polyethylene oxide tape as compared to direct seeding. Radial or cotyledon fractions from tomato seed germinated in solutions containing growth of mycelium of R. solani and P. aphanidermatum was significantly various levels of polyethylene oxide. Conventional methods of direct seeding small-seeded vegetable cm, in polyox tape. crops involve the use of a bulk-metering system and subsequent Seedling disease experiments were conducted in the greenhouse hand or machine thinning of the emerging plant stand to the desired in artificially infested soil in bench beds. Four beds, each 1.6 m X 1.3 plant density. Due to increased production costs, growers are m, were filled to a depth of 15 cm with a mixture of sand and interested in precision planting techniques which eliminate the need Marietta silty clay loam (1:1, v/v) and planed to a uniform level. for thinning (2). Two beds were infested with R. solani and two with P. Chancellor (1) described a technique of precision planting aphanidermatum. Inoculum for infesting beds was prepared by whereby the desired number of seed, with desired spacing, were blending a 3-day-old PDA culture of R. solani or P. placed on a water-soluble paper tape. However, seedling emergence aphanidermatum with 100 ml of water in a Waring Blendor. in field plots was less than acceptable. Recently, a polyethylene Twenty milliliters of the resulting suspension was placed on 400 cm 3 oxide (Polyox) tape (4) was developed as a seed carrier (Creative of a Perlite/cornmeal/Czapek's medium (10:1:2, v/v) in a 75 X100Agricultural Systems, Union Carbide Corp., Salinas, CA 93901). mm storage dish and incubated at 28 C for 14 days. Inoculum was This tape (trade-named EVENSEED) dissolves in 1.0-1.5 min removed from a dish, broken into individual particles, and when placed in soil with adequate moisture for seed germination, scattered uniformly on the soil surface of a bench bed. Inoculum The placement of seed on tape appears to be the most accurate of all was mixed into the upper 5 cm of soil and the soil planed to a methods for precision planting of small-seeded vegetable crops (3). uniform level. Treatments were thiram-treated seed, nontreated Uniformity of seedling emergence and increased plant stands seed, thiram-treated seed in polyox tape, and nontreated seed in obtained from polyox-taped seed are thought to be primarily due to polyox tape. Nontaped treatments were planted by hand-dropping spacing accuracy. However, differences in the incidence of 21 seeds in clumps of three seed every 23 cm within the row. Taped damping-off, within tomato plantings comparing taped and treatments were planted by placing 1.5 m of the polyox tape nontaped seed, suggests that other factors may be involved containing seven clumps of seed on the bed surface. Rows were 1.5 (authors, personal observation). m long and 15 cm apart. Soil was added to the bed surface and This study was conducted to determine the effects of polyox tape gently planed so that all seed were at a depth of approximately 1.9 on: emergence of tomato seedlings from soil artificially infested cm. There were two replications for each treatment in each bed with Rhizoctonia solani KiIhn or Pythium aphanidermatum resulting in four replications for each treatment for each (Edson) Fitzp.; growth of R. solani and P. aphanidermatum in organism. The experiment was repeated once. Emergence and culture; and seed germination and subsequent seedling growth of postemergence damping-off were recorded daily. tomato. The effect of polyox tape on the mycelial growth of R. solani and P. aphanidermatum was studied on water agar (1.5%, w/v) MATERIALS AND METHODS amended prior to autoclaving with 0, 1,200, 2,500, 5,000, 10,000, Soil from two fields in which tomatoes were grown the previous and 20,000 Mg! ml of polyox tape. Mycelial plugs, 5 mm in diameter, year was placed in flats in the greenhouse and planted with nontreated seed of tomato (Lycopersicon esculentum Mill., 'Tamu Chico III'). All seedlings were harvested and diseased tissue plated TABLE 1. Effect of polyox tape on emergence of tomato seed in soil on Difco potato dextrose agar (PDA). Organisms most commonly infested with Rhizoctonia solani or Pythium aphanidermatumy isolated were R. solani and P. aphanidermatum. Emergence (%) Two lots of Tamu Chico III seed (Ferry Morse Seed Co., Mountain View, CA 94040), one treated with thiram Treatments R. solani P. aphanidermatum (tetramethythiuram disulfide, 170 g per 45.4 kg of seed), the other Thiram-treated seed 68.8 az 67.8 a nontreated, were subsequently utilized in this study. A portion of Thiram-treated seed in polyox tape 59.4 a 68.5 a each seed lot was forwarded to Creative Agricultural Systems Nontreated seed in polyox tape 51.9 a 47.0 a where each lot of seed was placed, in clumps of three seed every 23 Nontreated seed 18.1 b 5.9 b 'Average of two tests. 0031-949X/80/06055802/$03.00/0 ZMeans followed by the same letter within a column are not significantly @1980 The American Phytopathological Society different (P = 0.05) according to Duncan's new multiple range test.

Carvajal is a graduate student in the MSU Department of Plant and Soil Sciences. For more information, contact Dr. Batson at (662) 325-2585; e-mail, bbatson@plantpath.msstate.edu. This research report was published by the Office of Agricultural Communications, a unit of the MSU Division of Agriculture, Forestry, and Veterinary Medicine. It was edited and designed by Robert A. Hearn, publications editor. Vol. 22, No. 10 Research Report March 2000