All Issues

Squash and related plants of the genus Cucurbita are monoecious, having both male (staminate) and female flowers (pistillate) on the same plant. To insure fertilization under natural conditions, pollen from the male flower must be carried to the stigma of the female flower by insects. Although other insects, including cucumber, scarab, and meloid beetles, flies and moths are also involved, bees are the major pollinators.

Spraying young regrowth shoots of mechanically top-pruned lemon trees with Maleic hydrazide (MH) resulted in a significant inhibition of growth for almost a year after treatment in tests reported in this article. Top growth was retarded Nithout appreciably affecting fruit quality 3r yield through use of a concentration of about 400 ppm of MH.

Crop damage possibilities, only limited responses in cotton yields, and residue problems for subsequent crops, as evaluated in this report of San Joaquin Valley tests, indicate the need for caution in use of preplant herbicides for weed control.

During the past three years, stripe rust has been a serious problem for California wheal growers. Several varieties introduced from Mexico under the continuing University of California cereal variety improvement program have been found to provide some protection from the disease. In California tests these varieties produced excellent yields in the presence of stripe rust and in general have equalled established California varieties in yield and agronomic characteristics when stripe rust was not a problem. Although tests in cooperation with the California milling industry have shown the re. sistant or tolerant Mexican varieties to be somewhat deficient in quality, they can be used when they meet the standards normally required by the milling industry. These deficiencies apparently are no greater than those existing in currently used California varieties. Until more information on their general acceptability is available, production of these varieties probably should be limited to districts with recurrent heavy losses frcm stripe rust. Programs to develop varieties which are resistant to stripe rust and more acceptable in other characteristics are underway.

In contrast to results of previous years, May-planted beets became 44% infected with yellows and did not yield as well as March and April plantings in 1963 tests at Davis. Three sprays, for aphid control, applied to May-planted beets, increased production 9.5 tons of roots per acre, 5.3 more tons of roots per acre than beets planted in March.

Soil mixes have been proposed and are being used by nurseries for various reasons. Evaluations of their properties relating to disease control and fertilization have been well documented. The selection of mixes for favorable physical properties is equally important, but methods for routine evaluations of such properties have not been sufficiently explored. The following data show evaluations of physical properties measured with laboratory techniques and, for comparison, similar measurements on mixes as they are used in gallon cans under nursery conditions.

Experiments in the Imperial Valley con- firmed that flax does not produce blooms and capsules continuously but in distinct, successive cycles. Even in a high-yielding field of flax only a small proportion of mature capsules were found to have the full complement of ten seeds.

Phytophthora root rot has become one of the most important diseases of alfalfa in California. It is particularly a problem on heavy, poorly-drained soils, or on any soil where a layer of free moisture persists for some time after irrigation. Leaves of the diseased plants turn yellow and eventually the plants die. Reddish brown lesions are found on the roots of the infected plants with the woody tissue of the root showing a yellowing above and below the lesion. Improving the drainage is the best control for the disease, but in some soils this may not completely solve the problem.

Future publications and other communications of the University of California will report amounts or percentages of a plant nutrient (whether in the plant, in the soil or in a fertilizer) in terms of the chemical element itself. This policy, aimed at simplification and the use of less confusing terminology, follows a similar official change by the American Society of Agronomy and a growing trend in publications of other states as well as within the fertilizer industry.