Calag Archive

In the urban area of Fresno, a group of youth campaign to make public transportation more widely available in their community.

In general, species of Aphytis are the most effective of California red scale parasites. Species of Comperiella, Prospaltella, Physcus, Aspidiotiphagus and Habrolepis are usually less effective but may act in a complementary manner. Several species of Aphytis are recorded to be partially to completely effective in biological control of the California red scale, Aonidiella aurantii (Maskell), in various citrus producing countries. Aphytis melinus DeBach, originally from India and Pakistan, is now established in California, Argentina, Australia, Greece, Israel, Cyprus, South Africa, and elsewhere. Aphytis lingnanensis Compere, originally from southeast China, is now in California, Mexico, Texas, and elsewhere. Aphytis coheni Debach is important in Israel; A. chrysomphali (Mercet) has been of some consequence in California, Australia, Greece, Israel, and elsewhere; and A. africanus Quedneau is considered important in South Africa.

Aphids commonly occur as pests on chrysanthemums and carnations as well as on many other plants grown in plastic or glass houses in California. They are usually found in colonies on plant tips, shoots of new growth, or flowers. Aphids multiply so rapidly under favorable conditions that a light infestation may increase to alarming proportions in a week. They are generally more numerous during cooler months when the most serious damage occurs. However, damage can be observed throughout the year.

Downy mildew of lettuce, caused by the fungus Bremia lactucae, can cause considerable damage especially to early spring and late fall crops in coastal areas. It is favored by cool, moist weather and may occasionally cause economic damage in the Imperial Valley during the winter lettuce season. Trials were initiated in the summer and fall of 1976 to compare new systemic fungicides from Ciba Geigy with commonly used materials.

The production and marketing of Christmas trees in California can be described as a “growth” industry in more ways than one.

Potato blackleg and soft-rot of tubers, caused by Erwinici carotovora var. carotovora and E. carotovora var. atroseptica, respectively, continue to cause mild to severe field, shipping, and storage losses of potatoes in California. An understanding of the survival capabilities of the bacteria and the factors that contribute to their spread is essential for the development of effective controls for these diseases. Previous studies have demonstrated that (1) the bacteria are seed-borne, and (2) they overwinter in the lenticels and stem-end portions of the seed tubers. Whether the bacteria can survive in soil, however, has been much more controversial, primarily because of the lack of sensitive techniques for detecting bacteria populations below 1000 cells/g of soil.