Soybean Production as Affected by Tillage in a Corn and Soybean Management System: II. Seed Treatment Response

Abstract

While fungicide seed treatment is needed for crops such as corn (Zea mays L.) and cotton (Gossypium hirsutum L.), its importance is not as well defined in soybean [Glycine max (L.) Merr.]. This study evaluated the effectiveness of seed treatment on eight soybean cultivars grown in a corn-soybean rotation with five tillage systems. Nontreated soybean seed was compared with seed treated with either captan (N-[(trichloromethyl)thio]-4-cyclohexene-1,2-dicarboximide) or metalaxyl (N-(2,6-dimethylphenyl)-N-(methoxyacetyl)alanine methyl ester) in no-till (NT), ridge-till (RT), fall moldboard plow (MP), fall chisel plow (CP), and fall Paraplow (PP) tillage systems at Morris, Lamberton, and Waseca, MN. Tillage did not affect response to seed treatment at any location. Seed treatment affected soybean performance at Waseca only in 1986 where captan and metalaxyl seed treatments significantly enhanced soybean stands and increased soybean yield of ‘Elgin’ and ‘1677’. At Lamberton, both seed treatments improved stand and yield of Elgin in 1986. Poor germinability and seedling vigor of the Elgin seedlot likely resulted in its large response to seed treatment. The cultivar 1677 appeared to be very susceptible to seedling diseases and thus responded to seed treatment in 1986 at Waseca when soil was relatively wet for 6 wk after planting. Based on the results obtained in these studies, seed treatment generally is not necessary to obtain adequate stands and high yields in soybean. Response to seed treatment was related to seed quality and cultivar susceptibility to seedling disease rather than to tillage practices.