Calag Archive

Full utilization of the biological method in fly control requires the preservation of existing predatory and parasitic enemies in animal dung. The use of residual poisons to control adult flies did not interfere with natural enemy complexes in these tests. Alternating the removal of manure deposits, and abstaining from chemical treatment of manure were essential procedures in maintaining largest populations of predators and parasites.

Since 1955, the average herd size in the Fresno County Dairy Herd Improvement Association (DHIA) has increased from 105 to 256 cows per herd. This expansion has been accompanied by an increase in production of milk from 9,433 to 13,592 pounds and of butterfat from 391 to 509 pounds per cow. Mastitis is one of the problems in dairy management which becomes more complex as herd size increases. Clinical mastitis cases can be recognized readily; however, it is also of great economic importance to determine which cows in a herd have nonclinical cases of mastitis.

Earlier studies of insecticides for fly control have shown that resistance is unequally distributed in California's numerous species of flies and that one chemical used for the control of the little house fly, Fannia canicularis, may not result in effective control of the house fly, Musca domestica. These differences in chemical effectiveness are particularly noticeable when poor control permits numerous adults to cause a serious nuisance problem on agricultural premises. In some cases, it may be profitable to spray for control of fly larvae in the manure and thereby prevent adult fly emergence.

Results of these 1967 experiments indicate that the combination of toxaphene plus DDT is still the most effective and economical insecticide treatment for boll-worm control.

Size and placement of furrows, and the use of grass culture can have a marked effect on irrigation water penetration rates, according to these tests in Fresno County vineyards.

The Two-Spotted Mite, Tetranychus urticae, has been very difficult to control during the past three hot summers. Walnut growers in Merced County, as well as in many other interior valley counties, have experienced early loss of leaves from walnut trees, sunburning of nuts and limbs, and problems with leaves on the ground at harvest.

The greatest proportion of dry-matter yields of annual and perennial ryegrass, as measured in rod-row field trials, occurred mostly in April, May and June at Davis, while orchardgrass yields were more evenly distributed throughout the harvest season. Ryegrasses generally were more vigorous and higher yielding than orchardgrass in the first year. Total seasonal yields in the first two years of the trial averaged 3.8 tons per acre for 14 perennial ryegrass selections and 3.4 tons per acre for five orchardgrass selections. These findings resulted under conditions of this trial and are not necessarily predictive of results under grazing management.