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Crop selection and soil management practices can be based on accurate estimates of evapotranspiration—water loss from the soil by direct evaporation and by plant transpiration—derived from climatic analysis. Growth of crop plants is dependent on the three major factors of soil, climate and management. Soil and management have been studied more thoroughly and are better understood than the factor of climate.

The sorghum midge—Contarinia sor-ghicola (Coquillet)—the most important pest of grain sorghums in the Southern states—was found in Tulare county on October 6, 1960. This apparently is the first record of this midge west of New Mexico. Surveys at the time of the initial discovery indicate that it is firmly established in Tulare County and is also present in Madera, Fresno, Kings, and Kern counties.

Head smut—Sphacelotheca reiliana—a soil-borne fungus disease, which can not be controlled by chemical seed treatment, is one of the most destructive enemies of corn, sorghum, and sudan-grass. It has become established in central California and appears to be increasing in severity and spreading in area.

The majority of soils in California are alkaline or, at least, not sufficiently acid to need lime. However, there are areas in the state where soils are naturally acid and other areas where continued use of ammonium fertilizers has produced acid conditions. The acidity of some of the soils is sufficient—pH values less than 5—to indicate that many crops should give higher yields when limed.

A nitrogen fertilization program for oranges can affect fruit production, fruit quality, fruit size, and consequently the pack-out.

Plum rusty blotch, a graft-transmissible disease of Japanese-type plums, has been observed on several commercial varieties throughout the plum-growing areas of California. During 1960 trees showing symptoms of plum rusty blotch were found in Fresno, Kern, Madera, Merced, Placer, Riverside, San Bernardino, San Joaquin, Santa Clara, Santa Cruz, Solano, Stanislaus Sutter, Tulare, and Yuba counties. The disease has been noted on the varieties Elephant Heart, Howard's Miracle, Kelsey, Laroda, Late Santa Rosa, Redroy, and Santa Rosa. The transmitting agent is not known.