Toxic Action of Aqueous Sodium Chlorate on Nitella1
TOXIC ACTION OF AQUEOUS SODIUM CHLORATE ON NITELLA1 By H. R. OFFORD, Agent, and R. P. D'URBAL, Assistant Chemist, Division of Blister Rust Control, Bureau of Plant Industry, United States Department of Agriculture INTRODUCTION The experiments herein reported on the toxic action of aqueous sodium chlorate on Nitella were conducted as part of an investigative program ^ to devise economic methods for the chemical suppression of wild currant and gooseberry plants. These plants, members of the family Grossulariaceae and commonly referred to as Ribes, are the alternate hosts of the blister-rust disease of white pines, which is caused by the fungus Cronartium ribicola Fisch. Blister rust may be effectively controlled by hand eradication of currants and goose- berries within 900 feet of the white-pine stand delimited for protection, though in the case of certain highly susceptible species of Ribes this distance necessarily must be increased. Hand pulling is an effective eradication practice, but a cheaper method, such as chemical treat- ment, is needed where the plants occur in great profusion. High toxicity, low cost, and adaptability to field use are important requi- sites of a chemical for general use in plant-eradication work. In field experiments more than a hundred chemicals were tested as plant poisons during the summers of 1925, 1926, and 1927 (P).^ The results of these experiments showed that sodium chlorate is by far the best killing agent and in addition lends itself suitably to general field application. Sodium chlorate, fully effective on Ribes petiolare Dougk, is but moderately successful on other Ribes. Field experiments performed during three successive years established this difference in susceptibility very definitely and suggested that, in the mechanism of killing, specific reactions between the chlorate and the several Ribes species are involved.
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