Evaluation of Deep-Chiseled Anhydrous Ammonia as a Control for Phymatotrichum Root Rot of Cotton. C. M. Rush, Texas Agricultural Experiment Station, Blackland Research Center, Post Office Box 748, Temple 76503. S. D. Lyda, Department of Plant Sciences, Texas A&M University, College Station 77843. Plant Dis. 68:291-293. Accepted for publication 3 October 1983. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/PD-68-291.

A 5-yr study was conducted to evaluate an anhydrous ammonia (NH₃) fumigation for controlling Phymatotrichum root rot of cotton. NH₃ (112 kg/ha) was chiseled 40 cm deep into the soil with a Big Ox chisel plow. NH₃ distribution studies showed the retention zone to be about 25 cm wide. NH₃ fumigation was compared with deep chiseling without NH₃ and conventional tillage as a means of controlling root rot. Despite the known toxicity of NH₃ to Phymatotrichum omnivorum, the NH₃ treatment was no more effective in controlling Phymatotrichum root rot than deep chiseling alone. The highest amount of disease and lowest yields occurred in the conventional tillage plots.