Calag Archive

Man's exploitation of his surroundings with disregard for nature's interrelationships has led to serious environmental problems including pollution of the air, water, and land. All of man's activities influence his environment in one way or another. The problem is to find ways to minimize this influence and make sure that these activities disrupt the environment as little as possible.

WEED CONTROL IN CITRUS nurseries is one of the most expensive cultural practices in citrus tree production. Earlier research has shown Simazine (Princep), diuron (Karmex), bromacil (Hyvar X), terbacil (Sinbar), and paraquat can be used effectively around bearing citrus. However, very few herbicides are usable on the 67,000 acres of young non-bearing citrus in California. The object of the studies reported here was to evaluate several herbicides for pre- and post-emergence weed control in citrus nurseries.

A NEW NONDORMANT ALFALFA Strain (SW44), segregated for stem nematode resistance and tolerance to leaf and stem diseases, has been developed through the joint efforts of the University of California Agricultural Experiment Station and Agricultural Extension Service, and the U. S. Department of Agriculture Entomology Research Division.

IT HAS BEEN KNOWN for many years that the apical buds inhibit the growth and development of lateral buds. This inhibition is largely due to growth regulators produced by the apical shoot and leaves. Other researchers have reported that buds are also inhibited by the presence of growing leaves—and that in several herbaceous species, the expanded leaves partially inhibited their axillary buds. Long after the removal of the terminal buds, the leaves delayed axillary bud growth. Defoliation has been shown to significantly accelerate bud growth of Poncirus trijoliata. However, length of time to bud growth varied with the season. The addition of 1 per cent NAA in lanolin paste to the leaf scars of defoliated plants inhibited bud growth. This auxin produced by the leaves may be responsible for inhibition of bud growth, as is auxin produced by the apical bud.

Studies with Ethrel (2-chloroe-thanephosphonic acid) on pickling cucumbers have demonstrated the effects of this chemical plant regulator on sex expression and growth development. Recently several research workers have reported favorably on the influence of this ethylene releasing compound on tomato fruit development and maturation.

PREVIOUS EXPERIMENTS have shown that the response of commercial potted poinsettias to growth retardants varies widely according to plant variety, type of chemical used, rate and time of application. The objective of this 1968 trial, conducted at Paul Ecke, Inc., San Diego County, was to determine the response of the newly released variety, Eckespoint C-1.

Azodrin and Temik were the most effective materials for control of thrips on chrysanthemums in these tests. Both materials gave quick and long-lasting control.

Irrigated pastures can compete successfully with many other California field crops—providing that careful control is kept of livestock stocking rates, that efficient irrigation practices are maintained, and that high yielding, well-adapted, palatable forage species are used.