Calag Archive

Panicle blanking, or the occurrence of “empty” kernels” on the rice panicle, may have caused yield losses of up to 12.5 per cent in 40 rice fields grown for certification in 1971. Although varieties differ in susceptibility to blanking, causes other than resistance appear to be responsible for the range in panicle blanking from 3.81 to 25.46% in different fields. Low night temperatures during pollen formation are believed to be the major cause of blanking. Pollen formation occurs during a 5-day period about 10 to 16 days before heading. Further studies aimed at finding solutions to this problem are in progress.

Mechanical thinning does not reduce the need for annual dormant pruning. Pruning reduces the potential crop, but more importantly it is essential for the renewal of fruit wood and in maintaining the general shape and vigor of the tree. However, this study showed that in a heavy set situation, mechanical thinning is a tool that can be used to increase average fruit size, decrease the percentage of under-size fruit, and reduce tree breakage from overcropping.

Lead found in and on crops in these highway proximity tests was caused principally by aerial deposition. Substantial amounts of Pb were removed from exposed plant tissues by distilled water washing. Amounts of Pb in and on crops were influenced by distance from the highway, extent of plant surface exposed, external plant characteristics, duration of plant exposure, motor vehicle traffic density, and direction of prevailing winds. In soils and suspended air particulates, concentration of Pb was influenced by distance from highways, and the direction of prevailing winds.

Tests have been conducted for several years with the support of the table grape, raisin, and wine industries, on pest management practices for spider mites and associated pests in the southern San Joaquin Valley. A major part of this effort has emphasized the correction of a spider mite imbalance in vineyards. Willamette mite (Eotetranychus willamettei Ewing) and Pacific mite (Tetranychus pacificus McGregor) had become difficult and expensive to control, and over-emphasis on chemical control programs was making the situation worse. Grape growers in Fresno County alone had been spending approximately one million dollars annually for spider mite control, and considerable vineyard damage still occurred. Moreover, it was observed that vineyards with histories of little or no pesticide use had few, if any, spider mite problems.

The Ranchita Range Study in San Luis Obispo County demonstrated that the complete conversion of California brushland to grass and legumes using mechanical clearing methods can be economical, improve wildlife habitat, lower fire hazards, and increase aesthetic values. By concentrating on the more productive sites, annual beef production amounted to 60 to 160 lbs per acre, and investment costs were recovered in five to 10 years.