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Influence of Nutrition on Stalk Rot Development of Zea mays. T. S. Abney, Former Research Associate, Department of Botany and Plant Pathology, Iowa State University, Ames 50010, Present address of senior author: Crops Research Division, ARS, USDA, Lafayette, Indiana 47907; D. C. Foley, Associate Professor, Department of Botany and Plant Pathology, Iowa State University, Ames 50010. Phytopathology 61:1125-1129. Accepted for publication 23 April 1971. DOI: 10.1094/Phyto-61-1125.

Breaking strength at 10 days after mid-silk was used as an estimate of inherent stalk strength, which was highest for plants of resistant and susceptible hybrids grown on plots receiving potassium. The hybrid of intermediate resistance to stalk rot had a higher inherent stalk strength in plots receiving nitrogen. Stalk strength decreased late in the growing season. Symptoms of stalk rot became evident 60 days past mid-silk. Incidence of stalk rot was negatively correlated with stalk strength, and was positively correlated with pith condition ratings. The frequency of rotting was high for the hybrids on all fertilizer treatments on the final observation date. The difference in rotting of stalks grown on nitrogen and no-nitrogen treatments was not significant. Nitrogen consistently increased the pith condition ratings, and potassium consistently decreased the pith condition ratings 10 days after mid-silk. Both fertilizer treatments reduced the pith condition ratings after frost. Stalk rot development in plants grown on potassium treatments was reduced at 60 days past mid-silk, but all hybrids were severely rotted by 10 days after the first killing frost. Measurements of stalk strength, pith condition, and natural rotting indicated that stalk rot was delayed in plants grown on potassium-treated plots.

Additional keywords: Fusarium moniliforme, Gibberella zeae.