Calag Archive

There is now ample evidence that integrated control has been proven a better approach than total reliance on pesticides, for solving a wide variety of pest problems. Integrated control emphasizes the fullest possible use of existing mortality and suppressive factors in the environment. It is not dependent upon any specific control procedure but rather coordinates, within the agricultural environment, the appropriate management techniques with natural regulating and limiting elements. Successful programs developed in many other parts of the world include integrated control for pests of citrus in Israel, for deciduous fruit pests in Central Europe and Nova Scotia, and for cotton pests in Peru. Other integrated control projects are now being developed for olives in Greece, for maize in parts of Latin America, for rice in India and Japan, and for cotton in Colombia. Crop protection specialists all over the world are moving rapidly toward the integrated control approach in efforts to help solve the critical food problems facing the world today. This issue of California Agriculture includes progress reports on several phases of the University of California Integrated Control Program for Grapes.—Ray F. Smith, Chairman, Department of Entomology and Parasitology, University of California, Berkeley. The grape leaf folder, Desmia funeralis Hubner, is apparently an introduced pest without effective natural enemies in California. However, some 14 species of parasites and predators were found to attack the grape leaf folder in the eastern United States. Three of the most promising species have now been released in California vineyards for biological control of this pest. One of these, Macrocentrus, is shown on the cover. Photo above is of the parasitic wasp, Apanteles, depositing eggs in larvae of the grape leaf folder.

Trials with the microbial insecticide Bacillus thuringiensis have been continued during the last three years to compare it with carbaryl, the standard control measure for grape leaf folder control (Desmia funeralis Hubner). Carbaryl gives excellent control of grape leaf folder but under some conditions it also produces biological upsets leading to increased spider mite and grape leafhopper populations. The overall evidence of the last three years shows that Bacillus does not increase spider mites or grape leafhoppers, and that it is usually, but not always, as effective as carbaryl. Timing of application is of critical importance with Bacillus treatments, however, whereas carbaryl applications are effective within a fairly broad range of time.

THE RESISTANCE of insect and spider mite pests of grapevines in many areas of the San Joaquin Valley to insecticides has led to the use of combinations of insecticides and often to more frequent applications for control. In view of the history of the use of combinations of chemicals for control of insecticide-resistant pests, these insects and spider mites may soon become resistant to the combinations now in use. Although a great many combinations may be tried and some new ones may be found effective, grape growers need additional and more effective acaricides. To this end, many newer chemicals (not registered for use on grapes) have been tested in the field for the past several years. Some of these are nearing registration and general use; however, the University of California does not have sufficient information to recommend any of these new materials for use on grapevines at the present time.

WHEN THE GRAPE integrated control project was started in 1961, the grape leafhopper, Erythroneura elegantula Osborn, was believed to be the primary pest of vineyards in the San Joaquin Valley. Also, it was believed that chemical treatments to control this insect were responsible for the increase of secondary pests such as spider mites. The basic aim of these studies was to determine what levels of leafhoppers could be tolerated without need of chemical treatments.

Many field observations have caused speculation by both growers and researchers regarding the coincidence of higher spider mite populations on plants with foliage covered with fine road dust. This association occurs more commonly near roads or avenues which are heavily traveled. These investigations indicated that road dust alone did not stimulate or affect the mites in a manner which might result in higher populations.

THE SPIDER MITES, Tetranychus pacificus McGregor and Eotetranychus willamettei (Ewing) have increased to abundance in vineyards since World War II. In at least some cases it appears that organic pesticides have caused an imbalance in the occurrence of spider mites and their natural enemies, particularly by inhibiting action by Metaseiulus occidentalis (Nesbitt) —a predatory mite. Chemicals may cause imbalance in vineyards by differential kill of predators and prey, by conferring an advantage to the prey (by stimulating reproduction), or by a combination of the two.

Exterior white latex paint applied to trunks of young trees before flatheaded borer eggs were deposited, but after bud break, prevented sunburn and reduced borer attacks—and was as effective as any other material tested in these studies.

The maturity of table Thompson Seedless was not affected in these tests by the time of application of berry-enlarging sprays of gibberellin, whether the sprays were applied when the grapes were at the shatter stage or at one, two, or three weeks after shatter. The shatter and shatter-plus-one-week treatments did produce larger berries than did the two later spray treatments.

RH 315 is a new experimental herbicide with considerable promise for use in California agriculture. It is not registered for use. This is a progress report of cooperative research on a new product.

Studies indicate that the best approach to control of the omnivorous leaf roller at present is field sanitation and chemical treatment if necessary. Early French plowing and disking should forestall damage in vineyards not yet infested. Where infestation already has occurred, removing all mummified clusters from the vine along with the French plowing and disking will be necessary. A standard lead arsenate spray just prior to fruit formation looks promising in tests but further research is needed. Insecticide treatments may be needed later in the season where sanitation practices are not used, or have failed to provide sufficient control.

Fire in seedbed preparation (including ash from burning debris), appears to be essential for giant sequoia seedling survival, and was beneficial to survival of white fir seedlings in these tests at Whitaker's Forest, Tulare County.