STUDIES ON SEED DORMANCY, PLANT DEVELOPMENT, AND CHEMICAL CONTROL OF TARTARY BUCKWHEAT (FAGOPYRUM TATARICUM (L.) GAERTN.): III. CHEMICAL CONTROL AND EFFECTS OF COMPETITION

Abstract

The effects on Tartary buckwheat and barley of various chemical treatments, applied at different stages of plant development, were compared in field plots. For control of Tartary buckwheat there was no advantage in using two applications of 2,4-D (2,4-dichlorophenoxyacetic acid, ethyl ester) or of MCPA (methylchlorophenoxyacetic acid, butyl ester), 12 days apart, rather than a single application at a correspondingly higher rate. At comparable rates a low volatile ester (butoxyethanol ester) was more effective than regular 2,4-D ester (ethyl ester), especially at the later growth stages, and both were much superior to MCPA.In competition between Tartary buckwheat plants, total production of vegetative matter and seed increased somewhat with increasing number of plants per square yard, but, as expected, the single-plant yields decreased sharply. In barley plots infested with Tartary buckwheat sprayed with LV 2,4-D when the plants had 2–3 leaves, up to 50 buckwheat plants per square yard had not yet, during the time before spraying, affected the ultimate yield of grain. On sprayed plots there was a balancing effect between herbicidal injury to the grain and decreased weed competition. The effect of the interaction between these two factors was manifested in the yield of grain.