Growth Regulators on Beans

Field experiments designed to study the possible uses of plant growth regulators on several different varieties of beans grown under the diverse conditions of southern California had three general objectives: I, to investigate the possibility of increasing yield of green or dry lima beans, bush or pole snap beans by the application of sprays of plant hormones; 2, to delay the maturity of lima beans grown for the freezing process by spray applications 10 days to two weeks before the expected maturity of the plants; and, 3, prevent the shedding of pods from the early sets of fruit as a result of adverse weather conditions. Test plots were established, beginning in 1949, in the bean growing regions of Ventura, Orange and San Diego counties during all seasons of the year where beans were grown in commercial quantities. Treatments of 2,4-D-2,4-dichlorophenoxyacetic acid-were included in most of the experiments. At various times other compounds-including NAAnaphthaleneacetic acid-ortho-chlorophenoxyacetic acid 2,4,5-TP-2,4,5trichlorophenoxypropionic acid-rhodanine acetic acid and N-metatolylphthalamic acid were tested for their effectiveness. Results soon demonstrated that it was not possible to bring about a significant delay in the maturity of green Concentrated Fordhook lima beans by application of sublethal concentrations of 2,4-D at any time less than one month before the expected maturity of the crop. Because the main purpose of delaying maturity in beans intended for freezing would be to spread harvesting operations over a longer period when otherwise adverse weather tends to hasten the maturation of all beans-regardless of different planting dates-and weather conditions could not be anticipated that long in advance of harvest, this aspect of the problem was discontinued. Applications of 2,4-D and some other compounds two to four weeks after seedlings emerged gave some initially promising results, particularly in Ventura County. The results of one experiment in the Oxnard area are summarized in the accompanying table. The application of either 10 ppm-parts per million-or 20 ppm-acid equivalent-of 2,4-D in Influence of Treatment with 2.4-D on Yield of Shelled, Green Concentrated Fordhook Beans