Calag Archive

Seed treatment of lima beans with fungicides—effective protection against seed decay caused by soil-borne fungi— does not protect against the attacks of wireworms, seed maggots, and spring-tails. Wireworms bore into the parts of the germinating seeds and into the roots, causing stunting, disfigurement, or death of the plants.

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: 1, 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.

Seasonal average increases of 12% to 18% in fruit yield have resulted from experimental application of growth regulator sprays on blackberries. The experiments were conducted on the Boysen, Olallie and Thornless Logan varieties at Torrey Pines in 1955. Preliminary experiments completed a year earlier on the Olallie and Boysen varieties in Santa Cruz and Stanislaus counties had given some evidence that growth regulator sprays were effective in this respect.

Fruit size was not increased uniformly in all of the 1955 trials in which mature French prune trees were sprayed with 2,4,5-T. The increase in the fresh weight of sprayed prunes varied from none up to 23%.

A single spray of 2,4,5-T—2,4,5-trichlorophenoxyacetic acid—applied to apricot trees at the beginning of pit hardening increased fruit size as much as 47%, hastened maturity, practically eliminated preharvest fruit drop, and, under certain conditions, gave a red blush to the fruit.

Natural enemies—native insect predators and fungus diseases—helped to hold the spotted alfalfa aphid in check during the 1955 season. In some fields an epizootic—corresponding to an epidemic among humans—of a fungus disease prevented damage by the aphid.

Frosted scaleon walnuts—held in check by natural enemies—was almost an unknown problem in northern California until after DDT was used to control the codling moth.

About 5,000 young citrus trees—less than six years old—in the major citrus areas of California have been ruined or killed by 2,4-D within the past 10 years. Most of the injured trees were lemons, but extensive damage to young orange and grapefruit trees has been observed. Severe damage has been found on only a few trees more than six years old.