All Issues

Evidence of the effect of potassium-supplying fertilizers on citrus fruit size in the long-term experimental orchard at Riverside was obtained by determining the concentrations of this and other elements in the leaves.

The sugar beet crown borer—Hulstia undulatella—a relatively unknown lepi-dopterous pest of sugar beets caused severe damage to seedling and half-grown sugar beets in Yolo, Yuba, and Solano counties during 1949. Although it probably causes some damage annually it apparently has not been reported in the scientific literature as a California pest since 1905 when damage was reported at Chino, Huntington Beach, Oxnard, Spreckels, and in the Santa Ana Valley.

Wax sprays applied to trees of the sweet cherry varieties Black Tartarian, Lambert, and Bing did not increase the size of the individual fruits, in experimental work at Davis in 1946 and in San Joaquin County in 1949.

Natural enemies of the walnut aphid-one of the most destructive insects attacking walnuts in northern California—serve to keep the aphid population in check.

Populations of the alfalfa caterpillar can be reduced successfully by airplane application of the polyhedra virus, spreading an epidemic of wilt disease— polyhedrosis—among the pest.

Cantaloupe mosaic—a virus disease-has cut the production of early-summer melons in the desert valleys of southern California, particularly in the Imperial Valley.

Plant spacing trials for canning tomatoes were initiated in Yolo County in 1946. Since the introduction of the field seeded method plant spacing has become of special interest to tomato growers. In this method, the cost of establishing the field is the same regardless of the spacing, while in transplanted fields the cost will increase with closer spacings.

Excellent control of tomato insects with DDT and DDD was achieved during the three-year period, 1946-1949. DDT and DDD were used safely on canning tomatoes and, when properly applied, gave excellent control without creating an objectionable residue problem.

Under California conditions it is doubful whether a saving of labor by field snapping would offset the decrease in yield in the field, and the loss of usable asparagus by trimming in the cannery.

Housing in California might well require more lumber annually in the next two decades than was used in the peak of the 1920's.