Browsing by Author "Mozingo, R. Walton"

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    Incidence and Management of Seed Transmission of Cylindrocladium Black Rot of Peanut in Virginia
    Glenn, Deborah Lea (Virginia Tech, 2001-03-01)
    Seed transmission of Cylindrocladium parasiticum was investigated as a possible explanation for the higher-than-expected incidence of Cylindrocladium black rot (CBR) of peanut in fields fumigated with metam sodium. Sixty-three commercial seed lots from Virginia production fields were examined for the presence of seed with speckled testae, a symptom of seed infection by C. parasiticum. Speckled seed was present in conditioned seed lots in 1998, 1999, and 2000 at an average rate of 1%. Soon after pods were harvested, the fungus was recovered from speckled seed at high frequencies. During winter seed storage, pathogen survival remained high in seed stored at -13 and 4 C, but declined in some seed stored at 15 C and ambient temperatures. Speckled and normal seed with and without fungicide treatment was planted in steam-treated soil in the greenhouse and metam-treated field plots in 1999 and 2000. Speckled seed treated with captan + pentachloronitrobenzene (pcnb) + carboxin transmitted the pathogen to emerging plants in the greenhouse and field. Transmission levels depended on the amount of viable inoculum present in seed at the time of planting. In the field, yield losses were significant when 20% or more of the seed planted was speckled. The low incidence of speckled seed in commercial seed lots would not result in a loss of yield for growers, but may contribute to disease spread. Testing of additional seed treatment fungicides indicated that fludioxonil, tebuconazole, and thiram may offer the best protection against disease spread from seed transmission of C. parasiticum.
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    The Role of Host, Environment, and Fungicide Use Patterns in Algorithms for Improving Control of Sclerotinia Blight of Peanut
    Langston, David B. (Virginia Tech, 1998-04-09)
    An algorithm was developed for assessing disease risk and improving fungicide timing for control of Sclerotinia blight of peanut, caused by Sclerotinia minor. A 5-day index (FDI) of disease risk was calculated daily by multiplying indices of moisture, soil temperature, vine growth and canopy density and summing the values for the previous 5 days. Spray thresholds of FDI 16, 24, 32, 40, 48 were compared to a 60, 90, 120 DAP (days after planting) schedule and the standard demand program. Field trials in 1994 indicated that fluazinam (0.58 kg a.i./ha) applied at an FDI of 32 performed similarly to the demand program and was more efficient than the DAP schedule. However, the original FDI 32 algorithm triggered sprays 13 days subsequent to disease onset in 1995, indicating the need for improved vine growth and temperature parameters as well as DAP-dependent FDI thresholds. Results from 1996 and 1997 demonstrated that algorithms with new vine growth and temperature parameters coupled with DAP-dependent thresholds performed as well or better than the original FDI 32 algorithm, demand program, or DAP schedule. Protection intervals of 7 and 14 days improved the performance of iprodione (1.12 kg a.i./ha) while fluazinam provided protection for up to 21 days when applied according to the original FDI 32 algorithm. Planting date was evaluated for its effect on disease and fungicide use patterns. Late planting (20-28 May) delayed disease onset and reduced early season disease incidence three of the four years tested. When averaged across planting dates, the original FDI 32 algorithm performed as well or better than the demand program in 1994 and 1995, as did algorithms utilizing new vine growth and temperature parameters with DAP-dependent thresholds in 1996 and 1997. Chemicals for altering plant architecture were compared to defoliation by corn earworm and leaf spot for suppression of Sclerotinia blight. Chlorimuron (8.8 g a.i./ha) and withholding fungicide for leaf spot control demonstrated the most significant disease suppression and yield improvement. Results show the importance of fungicide timing and plant growth and canopy architecture modification for control of Sclerotinia blight of peanut.
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    VA-C 92R : a new high-yielding peanut variety
    Mozingo, R. Walton; Wynne, Johnny C.; Porter, D. Morris; Coffelt, T. A.; Isleib, Thomas G. (Virginia Agricultural Experiment Station, 1993-01)
    V A-C 92R is a new, high-yielding, large-seeded, virginia-type peanut (Arachis hypogaea L.) variety released in 1992 jointly by the Virginia Agricultural Experiment Station, the North Carolina Agricultural Research Service, and the Agricultural Research Service, United States Department of Agriculture. It was tested experimentally as VNC 851 in the Virginia-North Carolina Peanut Variety and Quality Evaluation Program (PVQE) from 1986 through 1991...
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    The Virginia 81 bunch peanut (VA 81B)
    Coffelt, T. A.; Mozingo, R. Walton; Porter, D. Morris; Allison, Allen H. (Virginia Agricultural Experiment Station, 1984)
    Peanuts are an important cash crop in Virginia, generally ranking fourth behind tobacco, corn and soybeans. However, production is limited to southeast Virginia where peanut is the number one cash crop. The gross farm value of the peanut crop reached a record high $91,239,000 in 1981. Peanut yields increased about 15 percent every five years until 1976. Since 1976, yields have remained steady, except for 1980 when severe drought reduced yields by two-thirds. Since 1976, the major limiting factor for yield has been diseases, the most important of which is Sclerotinia blight caused by Sclerotinia minor Jagger. This disease accounted for an estimated loss of 10.6 million dollars in farm income in 1981. Sclerotinia blight is found in about 50 percent of the peanut fields in Virginia and is also a problem in other U.S. peanut-producing states (North Carolina, Oklahoma and Texas), as well as other parts of the world. Virginia 81 Bunch (VA 81 B) is an early-maturing virginia-type peanut variety released in 1982 jointly by the U.S. Department of Agriculture, Agriculture Research Service and the Virginia Agricultural Experiment Station because of its resistance to Sclerotinia minor, earliness, and favorable agronomic traits. While not immune to this soilborne pathogen, VA 81 B should provide increased yields over currently grown varieties when planted in infested fields.