All Issues

A severe plant water deficit imposed for nine days during the peak flowering period of cotton reduced yield more than stress periods of comparable length imposed either early or late in the flowering period. Water stress occurring early in the flowering period reduced yields by increasing shedding of squares before they flowered. Stress late in the flowering period reduced flowering rates and boll retention.

Corporate farms tend to be larger, both in terms of acres of land operated and gross farm sales. California's farming corporations tend to concentrate in the intensive high-risk-capital enterprises. The rate of incorporation appears to have slowed considerably in the past three years. In the future, it is likely that existing corporations will expand the size of their present operations, along with some consolidation of smaller corporqtions through purchase by, or merger with, large diversified corporations. Also, as farms achieve a larger size, they will tend to adopt the corporate form of business organization.

Exposure of plants to ethylene gas has brought about various responses, including flower induction, change in direction of growth, accelerated fruit ripening, leaf and fruit abscission, and hastened seed germination. Research in 1967 revealed that fig fruits were stimulated to grow rapidly and mature early when exposed to an atmosphere containing 5 ppm of ethylene. The cost and inconvenience of confining a gas such as ethylene to fig trees makes impractical its application to induce early fruit maturity. On the other hand, application of a spray that produces effects similar to those of ethylene would be of great value to the fig grower. When applied as a water spray, the proprietary compound Ethrel (2-chloroethylphosphonic acid) penetrates the leaves and other plant organs and then decomposes to form ethylene, chloride, and phosphate. The results of experimentation during 1968 and 1969, described in this report, show clearly that the effects of Ethrel on fig fruit growth and maturation are like those of ethylene.

ZINC DEFICIENCY is one of the most serious nutritional problems of walnut production in California, and has been very difficult to correct. The most common treatment in past years has been the use of zinc-coated sheet metal strips driven into the sapwood of the tree. This method has been laborious and expensive and has required periodic treatments (every three to four years) to maintain deficiency-free trees. In some soils, trees have responded well to soil applications of zinc, while in other soils they have responded poorly. Soil applications of zinc at levels sufficient to achieve correction have often been very expensive.

Cotton research personnel and growers have often observed that some insect pests are more abundant in parts of a cotton field or in, entire fields where plant growth is rank and succulent. The research reported here was initiated to test this observation. Three different regimes of irrigation water and nitrogen, tested in factorial combinations brought about distinct differences in growth patterns between various plots. Throughout the course of the study the lygus bug, Lygus hesperus Knight, was found significantly more abundant in plots with high irrigation and nitrogen levels, than in plots receiving minimum applications of either variable. A complex relationship was found to exist between cotton lint production, vegetative plant growth, insect numbers, and water and nutritional management. The implication of these tests is that cotton growers may reduce the threat from insect pests through management of their irrigation and fertilization practices.

Two promising, early maturing cherry varieties, Early Burlat and Moreau, were recently introduced in California. Adequate pollination data for these varieties were not available at the time of introduction, so a study was conducted to develop this information. Early Burlat was found to be successfully pollinated by a number of commercially grown varieties. However, no satisfactory pollenizer for Moreau has been found.