Update on Seedling Disease Control in No-Till Cotton with Soil Fungicides, 1991-92

Albert Y. Chambers and Tracy D. Bush


 
ABSTRACT

Six fungicide treatments were evaluated each year during 1991 and 1992 for seedling disease control in a split-plot, no-till and conventionally-tilled cotton experiment at the University of Tennessee Milan Agricultural Experiment Station at Milan. Treatments were applied as granular and spray applications to the seed furrow during the planting operation, as a seed-overcoat treatment, or as planter hopper-box treatments. A combination of a seed-overcoat and a granular in-furrow treatment was included in 1991. Temik systemic insecticide granules were included alone and in combination with each of the fungicide treatments. Untreated plots were included in both tillage systems. Granular fungicide and insecticide combinations were applied from partitioned granule hoppers. Acid-delinted, commercially-treated seed were planted April 22, 1991, and April 23, 1992, into a well prepared seedbed in conventional-tillage plantings and into cotton stubble from the previous crop in no-till plantings using the same planter, seeding rate, and cultivar ('Stoneville 4531, 1991; 'Deltapine 501 ' 1992). Fertilization was the same for both plantings; herbicide applications varied as required for the two types of tillage.

Weather conditions were wet and fairly cool in 1991 and resulted in reduced stands in both tillages. Granular treatments of Ridomil PC and Start (Aliette-Rovral), spray application of Ridomil 2E plus Terraclor 4F, a combination of Ridomil PC granules at half-normal rate plus Delta-Coat AD seed-overcoat treatment, and DeltaCoat AD seed-overcoat treatment alone significantly improved stands compared to those in untreated no-till and conventional-tillage plots. Stands were also improved significantly in plots treated with Temik alone. Treatment with Terraclor Super X granules did not increase stands. Skip levels were reduced in both tillages by all treatments except Terraclor Super X in conventional tillage. Plant vigor was significantly improved in both tillages by all fungicide treatments and Temik alone. Yields were significantly higher in conventional plots of Terraclor Super X, Ridomil PC, and start granules, Ridomil PC plus Delta-Coat AD, Delta-Coat AD, and Temik alone. Yields were improved only in no-till plots receiving Start granules. Spray treatment of Ridomil 2E plus Terraclor 4F did not increase yields in either tillage. Yields from no-till plots averaged 124 lb./acre of lint higher than those from conventional plots.

In 1992, weather conditions were cool but dry at the time of planting and for several days thereafter. Granular in-furrow fungicide treatments of Terraclor Super X and Ridomil PC and hopper-box treatments of Apron-Terraclor and Prevail significantly increased stands over those in untreated plots of conventional tillage. Stands in no-till were increased significantly in plots receiving Terraclor Super X, Ridomil PC, and Start granules. Skip levels were reduced significantly only in no-till plots treated with Terraclor Super X, Ridomil PC, and Start infurrow granules. All treatments in both tillages reduced ratings of seedling disease injury to roots and lower stems. Plant vigor was improved in both tillages with all treatments compared to no treatment. Yields were not increased by any treatment in conventional tillage. Terraclor Super X, Ridomil PC, and Start granular infurrow, Delta-Coat AD seed-overcoat, and Apron-Terraclor hopper-box treatments improved yields in no-till plots. Temik alone did not increase yields in either tillage. Yields from no-till plots averaged 177 lb./acre of lint less than those from conventional plots. Yields in both tillages were over two bales/acre.

The difficulty of obtaining an adequate stand of cotton under no-till conditions, especially with early planting, was again confirmed in above research. Treatments of fungicides delivered to the seed furrow by various me thods and combined with a systemic insecticide improved stands, skip levels, plant vigor, and yields and lowered disease injury ratings (in 1992). Yields were higher in no-till than in conventional-tillage plots in 1991 and lower in 1992.



Reprinted from 1993 Proceedings Beltwide Cotton Conferences pg. 224
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998