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Tests in Riverside County to study the effectiveness of a helicopter for frost protection in citrus resulted in a beneficial response in both air and fruit temperatures.

NUT CROPS GROW PRIMARILY in the temperate zone and are irrigated to satisfy their moisture requirement. Irrigation of these crops is practiced where annual precipitation is less than 20 inches, or when rain does not fall during the water demand periods of the trees. Since nut trees are deciduous and are without leaves during the winter months, they use little water during that time. Precipitation occurring in the winter is stored in the soil if the profile is deep and uniform. In the Bakersfield area of California where this study took place, precipitation in the winter is limited to about 6 inches per year.

Taking advantage of predator populations, alternate prey species, grass cover, and sprinkler irrigation may all contribute to successful control of spider mite populations in raisin vineyards of the San Joaquin Valley.

A yellowing of leaf margins appeared in the summer of 1970 on mustard plants grown commercially on Bay Farm Island in Alameda County. The symptoms had a drastic effect on the saleability of the crop, and the yields were reduced by almost half.

Regrowth of trunk sprouts on eight of nine species treated with growth regulators was reduced by 85 per cent, as compared with untreated trees in these tests. The sprouts that did grow on treated trunks were only one-tenth to one-third as long as sprouts from untreated trunks. There was very little translocation of the growth regulators from the regions of application.

Although tree roots in sewers and drains cause losses of millions of dollars each year in the U. S., there has been very little research on control methods. This is a report of 2 1/2 years of chemical control tests in cooperation with the Sacramento County Department of Public Works. Two chemicals—metham (Vapam), and dichlobenil (Carsoron)—used alone, or in combination, killed roots in sewer pipes in one-hour-long treatments by soaking.