All Issues

Results of test plot research, along with commercial application experience, indicate that the use of oil sprays to control Pacific mite on grapes is promising. However, more information is needed on the causes and conditions resulting in plant injury before the use of oil sprays on grapevines can be recommended.

Studies to evaluate the practice of irrigating alternate furrows in cotton were conducted for two years on a sandy laom soil at the U. S. Cotton Research Station, Shafter. With an alternate-furrow irrigation system, soil moisture used by the plant before irrigating is replenished on only one side of the row at the time of irrigation. This system provides a more sensitive means of regulating plant water stress, which can be of help in controlling the vegetative growth rate of the plant. However, since the entire soil zone is not all used for water storage, care must be exercised to avoid excessive water stress. Total lint yields for alternate-furrow test plots were as good or better than yields for regular furrow irrigation, and with considerable less water used.

Sweet cherry trees in many commercial California orchards have been allowed to grow excessively tall. This practice tends to elevate the bearing area with subsequent loss of much of the lower fruiting wood. Cultural and harvesting operations then become more inefficient and expensive. Height of young bearing trees can be controlled and maintained by pruning. A reduction in yield often results from pruning bearing trees and is generally proportionate to the severity of pruning. However, this reduction in yield may be partially offset by somewhat larger fruit size, more efficient cultural and harvesting operations, and slightly increased tree vigor.

A Wide Variety of annual weeds in commercial vineyards have been controlled in recent years with chemical herbicides. Although very effective on these annuals, the use of such herbicides has actually increased difficulties with perennial weeds in many plantings. An active research program has been under way at the University to develop means of controlling these persistent pests. A number of foliar-contact and hormone-type herbicides have been recommended for use against them. However, there remains an urgent need for an effective soil-residual herbicide that would be effective against perennial weeds.

Of the many herbicides tested recently in California cole crops, FW-925 (TOK-E–25) —applied pre-emergence without incorporation—had the largest and most consistent margin of safety for direct-seeded cole crops. Such herbicides as DCPA, Glenbar, and bensulide also gave adequate control of certain weed species, along with an excellent margin of safety. Herbicides with less safety but with a wider weed control spectrum included trifluralin and CIPC. CDEC was effective on some important weed species, but had a somewhat narrower margin of safety. Combinations of herbicides—including trifluralin and FW-925 are being tested this year in uniform trials on cole crops throughout California. This is a progress report of research with new herbicides and is not to be considered a recommendation of the University of California. Many of the materials used in these tests are not registered for use in cole crops.

Visual sizing of cantaloupes for commercial marketing results in considerable variation among melons within packed shipping containers. This situation causes losses to retail grocers, who must pay for the additional labor needed to differentially price the various sized melons—and to sustain losses from the sale of undersized melons within packs. Attempts to measure cantaloupe volumes by diameters have not proved satisfactory. Results of this study of cantaloupe volume: weight relationships conducted during 1965–67 indicated that fruit weights could serve as an accurate measure of volume. This correlation was determined in a series of volume: weight relationship studies during the 1965, '66, and '67 seasons for PMR-45, the most commonly grown variety in California; for several commercial varieties grown under comparable conditions in a variety test plot at the University of California's West Side Field Station, and for Top Mark, a recently introduced commercial variety grown in the Imperial and San Joaquin valleys.

Sequoia, a new University of California strawberry variety, has been named and released for propagation and distribution—and has been further designated the Centennial strawberry variety in recognition of the University's anniversary this year. Fruit growers should direct requests for plants to California strawberry nurserymen. Some plants should be available in October for the 1968 winter planting season.