All Issues

The decline of citrus root systems is one of the more serious current problems in production and fruit size. During the past few years, quantitative information has been accumulating on the extent of citrus root decline and its relationship to growth and production.

An answer to whether high concentrations of sodium found in roots of lemon trees severely affected by decline—collapse—were the cause or the result of the tree's condition was the objective of a series of analyses of root and soil samples.

Two species of gall-forming root-knot nematodes—Meloidogyne incognita var. acrita and M. javanica—seem to be the most widespread of several kinds that parasitize California peaches. Consequently, first efforts toward selection of nematode-resistant rootstocks have been directed against these nematodes.

The Audubon's warbler and a wasp parasite work together to hold the calico scale—potentially destructive on walnuts —under control. This occurs even under conditions where—because of the tendency of the newer insecticides to interfere with natural enemies—other un-armored scale population has increased.

Refrigeration is necessary to extend the shelf-life of market fruits, and the sooner after harvest the better. Under current practice, it may take 12 to 36 hours for even the field heat to be removed from such table fruits as plums, apricots, peaches and grapes. However, orderly harvest and movement of the fruit to adequate refrigeration facilities will shorten the cooling time. Beyond the initial cooling, the shipper should supply adequate cold storage to insure the fruit being marketed in a fresh-appearing condition.

Exposure time required for the fast, efficient heat of infrared radiation to kill Lyctus powder-post beetles—in all stages of development—is governed by the thickness of the infested hardwood floor. Once the floor thickness has been determined and the exposure time known, 100% mortality of the Lyctus beetles can be expected under every square inch of area covered by a recently developed infrared unit.

A severe nutritional deficiency disease occurred in tomato plants growing in experimental cultures after chlorine was removed from the nutrient solutions.

Suffolk-sired lambs from grade Corriedale ewes gained faster than Corriedale-sired lambs during a three-year study at the Hopland Field Station. Also, male lambs were heavier than females within their own breed.

Ponderosa pine seedlings were used in a study of soil fertility changes induced by prescribed burning to learn whether nutrient responses would be reflected by a crop natural to the soil.

Drought-tolerating plants are useful for landscaping areas which do not normally receive irrigation water. They are especially adaptable to the rural home landscape because there is usually sufficient space for them to grow in areas which will not receive summer water. They can be valuable as windbreaks and screens for buildings and machinery.