All Issues

Since about 1776 California has been continually plagued by the inadvertent introduction of foreign plants that spread rapidly and become weeds. Examples include crabgrass (both smooth and hairy), yellow starthistle, oxalis, bermudagrass, and johnsongrass.

Many factors in soil interact to reduce the effectiveness of grapevine roots, compounding the debilitating effects of nematodes on grapevines. Since optimum grape production requires a healthy, vigorous root system, these factors must be considered in vineyard management.

Biological control involves discovering, importing, and using the most effective natural enemies of pest insects or weeds that can be found. More than 10 million natural enemies of many kinds are released each year by the University of California (UC) through its Biological Control divisions at Albany and Riverside.

Fireblight, caused by the bacterium Erwinio amylovora, is an erratic and devastating disease of pear orchards. Native to North America, it was first observed in California in the 1890s after slowly crossing the continent from the east, decimating pear orchards in its path. Fireblight has the potential to destroy an established orchard in one season if uncontrolled. With 37,440 acres of hearing trees producing a crop of 353,500 tons valued at $44 million, California pear producers have traditionally spared little in their protection efforts to keep the disease in check.

Coding moth, Laspeyresia pomonella (Linn), is one of the most serious pests attacking walnuts, Yet many growers and researchers have observed that certain walnut varieties are more susceptible to coding moth damage than others.

The quantities of jojoba seed available at present for extraction are too small to be handled by existing commercial oil seed processing plants, most of which have capacities exceeding 50 tons of seed per day. Instead, small mechanical presses or solvent extractors are being used. Following is a summary of experience we have gained on jojoba wax extraction to date.

Powdery mildew of rose, caused by the fungus Sphaerotheca pannosa, results in unsightly and frequently malformed leaves and flowers, and may reduce growth. Several new fungicides were evaluated for the control of powdery mildew in southern California commercial rose fields.

The sugar beet, a product of research, has been confronted with crisis after crisis in its role as a supplier of one of the cheapest and purest of foods. One of the most recent maladies to take heavy tolls in the production of this crop has been the aphid-transmitted yellowing virus diseases.