TURF and WEED CONTROL

R field experiments with one of the synthetic plant hormones of growth regulators, conducted by the USGA Green Section in collaboration with the Bureau of Plant Industry of the Dept. of Agriculture, have shown striking promise for the effectiveness of this group of chemicals in the control of clover and some of our more serious turf weeds. The application of aqueous sprays containing a spreader and 2, 4-dichlorophenoxyacetic acid, one of the growths regulat ing compounds, in preliminary exploratory tests on Kentucky bluegrass have given excellent control of clover without any apparent injury to the bluegrass. Although these preliminary experiments have been limited to tests with only one of the so-called plant hormones, other related compounds may in the fu tu re prove to be even more selective and effective in their herbicidal action. Pure 2, 4-dichlorophenoxyacetic acid is a white crystalline powder only very slightly soluble in water . In order to apply it in water solution a t the necessary concentration, a carrying agent or binder must be used in the preparation of the spray mixture. For this purpose a proprietary compound sold under the t rade name Carbowax No. 1500 was found to be ideally suited, since the hormones are readily soluble in it. It is an organic compound (a polyethylene glycol) which at room temperature is of the consistency of vaseline. Carbowax readily goes into solution in warm water. When used a t a concentration of 0.5%, tests have shown that it has no effect on creeping bent turf cut at putting green height.