Effect Of Fungicide Treatment Research Articles

Emergence and Yield of Fungicide‐Treated Soybean Seed Differing in Quality1

AbstractCurrent recommendations that soybean (Glycine max L. Merr.) seeds be treated with fungicides if they are of poor quality or to be planted in cool, wet soils, are too vague for the grower to be sure when treatment is warranted in the upper Midwest. This paper evaluates the effects of fungicide treatments on seeds with different quality characteristics under more precisely‐defined soil conditions than in previously reported studies. Seedlots of ‘Cumberland’, ‘Wells’, and ‘Williams’ with inferior quality due to age, damage, small size, or infection by Phomopsis spp. were treated with captan {N(trichloromethyl)‐thio]‐4 cyclohexene‐1,2‐dicarboximide}, carboxin‐thiram (5,6‐dihydro‐2‐methyl‐1, 4 oxathiin‐3‐carboxanilide, 17%; tetramethylthiuram disulfide, 17%), metalaxylN‐(2,6‐dimethylphenyl)‐N‐(methoxyacetyl) alanine methyl ester) or untreated. These were tested for emergence and yield in the field on two soil types [a poorly drained Webster silty clay loam (fine‐loamy, mixed, mesic, Typic Haplaquolls), and a well drained Clarion loam (fine‐loamy, mixed, mesic, Typic Hapludolls)] at three different planting times in both 1980 and 1981. Captan and carboxin‐thiram seed treatments were equally effective in increasing emergence in the laboratory and field of soybean seedlots with more than 15% Phomopsis spp. infection, but metalaxyl did not. No seed treatment consistently improved field emergence of seeds with reduced quality because of mechanical damage, age, or size. There were no obvious differences in fungicide performance in relation to planting dates or soil types. Increased yield in response to fungicide seed treatment was detected only in the 50% Phomopsis‐infected seedlot. We conclude that fungicide seed treatment cannot be justified on seeds of low quality for reasons other than disease under most of the soil conditions likely to occur in the upper Midwest. These results suggest that performance of seedlots with Phomopsis spp. infection exceeding 15% will be improved by fungicide seed treatment.

Effect of fungicide treatment on yield of winter wheat and spring barley cultivars

Analyses of the results of 21 winter wheat and 32 spring barley trials showed that cultivars differed significantly in their yield response to a standard fungicide treatment. Responses were also strongly influenced by differences between sites and between years. Regression analyses showed that responses were significantly related to reductions in foliar disease, particularly that of mildew, although the proportion of variance accounted for was small. Measurements made on seven winter wheat trials indicated that the percentage of leaf area remaining green after anthesis was increased by the fungicide treatment to a greater extent than could be attributed to reduction in foliar disease alone. In one of these trials, yield response was more closely correlated with the increase in leaf area remaining green than with reduction in foliar disease.

Fungicide Treatments of Blackgram Seeds for the Control of Storage Fungi

Blackgram seeds treated with five fungicides were stored for several months. Up to the initial storage period of three months, the effect of fungicide treatments on the yield potential of the stored seeds was not exhibited. But Thiram and Captan treatments maintained the potential for five months or more, while that of seeds treated with other fungicides or untreated. declined markedly.