Calag Archive

Dutch elm disease (DED) has devastated elm populations throughout large portions of the eastern and midwestern United States. This disease has gradually spread westward since its accidental introduction from Europe into North America in 1930. First discovered in California in Sonoma County in August, 1975, DED is a threat to elm populations throughout the state. The California Department of Food and Agriculture is committed to exploring the feasibility of eradicating the disease before it spreads from its initial infection sites.

Damping-off of cotton seedlings in southern California is caused by two fungi, Rhizoctonia solani and Pythium spp. Seed rot and seedling decline are particularly severe during cool, wet weather and when soil temperatures are below 60° F. Several new fungicides were tested against common, standard, commercial fungicides.

Yield potential of a crop is dependent upon genetic and environmental factors. The environmental factors can be manipulated to exploit the maximum yield potential of a variety. As new varieties are developed or introduced into an area, new and efficient cultural practices must be developed. This study at Tulelake was conducted under irrigation to determine the effects of planting dates and seeding rates on the yield and other agronomic characteristics of wheat, barley and triticale.

The Department of Entomological Sciences at the University of California in Berkeley offers the only diagnostic service in the United States with equipment and experienced personnel for formal laboratory diagnosis of insect diseases. The Diagnostic Service, started in Berkeley by Edward A. Steinhaus in 1944 as an aid to university entomologists, rapidly grew into a worldwide service. The Service was run by Professor Steinhaus and Gordon A. Marsh until 1964, and has been run by the present authors since then (fig. 1).

California commercial fertilizer sales have grown dramatically since 1955. Total sales of nitrogen (N) and potash (K) tripled while phosphate (P) sales more than doubled. Total fertilizer sales of 830,000 tons for the year ending June 30,1976 were distributed approximately 71 percent nitrogen, 22 percent phosphates, and 7 percent potash. The highly diversified and intensive cropping patterns characteristic of California agriculture will continue to require large amounts of fertilizer to maintain present levels of production.

Rauschkolb and Mikkelsen (“Survey of Fertilizer Use in California- 1973,” UC Division of Agricultural Sciences bulletin, forthcoming) estimated common fertilizer application rates and percentages of land fertilized by area for individual crops in 1973. We derived weighted statewide application rates from these estimates. Thus, our estimates of application rates are based on the cropping pattern existing in 1973. A significant change in the location of crop production in California could produce a substantial change in fertilizer use without any change in fertilizer prices or planted acreage.

The sunflower moth (Homoeosoma electellum Hulst.) will probably never be put on the endangered species list, but many California farmers would iike to see it as extinct as the dinosaurs because of the damage it does to the sunflower crop. This pest has also caused extensive damage to sunflower in Georgia, Kansas, Louisiana, Missouri, Nebraska, Texas, Minnesota, North Dakota, and in parts of Canada