Calag Archive

In connnection with a 1974 survey of 22 western states, we agreed to gather information on the types of crops in California taht are subject to iron deficiency and to estimate the acreage involved. Recognizing that the severity of the problem veries from year to year because of weather conditions, we concluded that the most useful information would be obtained from members of Copperative Extension who have long familiarty with field conditions in the various agricultural sections of the state. therefore, the information summarized below was obtained from Country Farm Advisors throughout California.

Annual weed competition in young orchards and vineyards can often reduce first-year growth as much as 50 percent. In fields with extremely heavy weed populations and limited irrigation, trees and vines have been killed by weeds in the first year. Perennial weeds are even more harmful than annual weeds to newly planted trees and vines. Even though a persistent tillage program can give a practical control of perennial grasses, many growers still have serious problems with perennial weeds.

Powdery mildew of rose, caused by the fungus, Sphaerotheca pannosa, results in unsightly leaves and flowers, and may result in reduced growth. Several new fungicides were evaluated for the control of powdery mildew in southern California rose gardens, and are reported here.

Liquid protein supplements (LPS) are available commercially for feeding to dairy and beef cattle. They are easy to handle and mix with other ingredients, but liquid nutrients are usually more expensive than dry nutrients. Ingredients and nutrient content vary among products, but most are combinations of molasses, urea, phosphoric acid, and small amounts of other minerals and vitamins. The liquid protein supplement Pro-Lix also includes fish solubles, fermentation solubles, and brewers yeast. It contains 35 percent crude protein of which 17 percent is derived from nonprotein nitrogen.

Road building and other types of construction activities on range and wild lands often involve considerable landscape manipulations and may cause serious soil erosion particularly on steep slopes with shallow soil. Some of these effects are noticeable in The Geysers area of northern California where there are about a dozen geothermal power plants in operation. Removal of vegetation and construction of drill pads, steam transmission lines, power plant sites, roads, parking lots, and electrical transmission rights-of-way mar the landscape and accelerate erosion. Furthermore, widespread concern over diminished energy supplies makes additional development of geothermal resources imminent. Therefore, steps should be taken to minimize ere sion by identifying critical areas before site disturbance.

The sugarbeet cyst nematode, Heterodera schachtii, is common in the Imperial Valley. About 50,000 acres of agricultural land have been found to be infested with this pest.

Drip and spray irrigation systems permit precise placement of a measured amount of water to soil. Designed for frequent, slow application of water, these systems make it possible to adjust the volume of water applied to soil in order to replace that which is removed from the soil through evaporation and plant transpiration (evapotranspiration). Use of drip and spray irrigation systems should lead to reduced water runoff from soils and more efficient use of water and nutrients needed for plant growth.

Citrus stubborn disease is a serious economic problem in California, in Southwestern United States, and in other arid citrus areas of the world. Knowledge of the disease has rapidly increased since 1969 when a mycoplasma-like organism was found by electron microscopy in thin sections of diseased leaves. In 1970, a mycoplasma, now named Spiroplasma citri, was cultured from diseased citrus tissue. Further research has revealed that two leafhoppers (see California Agriculture, November 1973) can transmit the stubborn disease organism. Cultured spiroplasma have been fed or injected into these insects and they, in turn, have transmitted stubborn to healthy citrus seedlings. More recently (see California Agriculture, February 1975), one of the insects, Scaphytopius nitridus, fed on diseased citrus trees was shown to transmit a severe disease to healthy Vinca rosea L., periwinkle plants, in controlled greenhouse experiments. This information prompted our investigating the possibility of natural spread of stubborn into periwinkle plants.

The large black rove-beetle Ocypus olens Msller (Coleoptera: Staphylinidae) (fig. 1) is established in some gardens in California. It was first introduced accidentally into California probably about fifty years ago and has since been reported in the counties of Contra Costa, Imperial, Los Angeles, Modoc, Riverside, San Diego, San Francisco and San Mateo. This active predator is now being viewed as a possible biological control agent of Helix aspersa Muller, the brown garden snail (BGS).