Calag Archive

Nuclear age needs for knowledge of the potential hazard to man from fallout on food—causing skeletal accumulations of strontium 90 (Sr⁹⁰)—are being served by the life-span experiments with 800 beagles underway at the School of Veterinary Medicine, Davis, under the sponsorship of the U. S. Atomic Energy Commission. These tests of low level radiation effects were started in 1957 and final data will not be available for 10 or more years. Some results to date include indications that pups can discriminate very little against Sr⁹⁰, assimilating almost 80% of the amount ingested in milk. Lactating dams discriminate against Sr⁹⁰ similar to adult dogs, and other species including man (about one-half of the ingested Sr⁹⁰ is assimilated). Observations of radiation-induced malignant tumors in beagles from ingested Sr⁹⁰ confirm results of experiments with smaller laboratory animals. Soft tissue cancers seem to occur at an earlier age than do bone tumors. Bone cancer in the beagle during the age of maturity has only been seen in those having high Sr⁹⁰ body burdens. The lowest cancer producing level of Sr⁹⁰ in the dog has yet to be determined. A wide range of incidental information on dog care is also being developed during the testing period. Modern cages have been designed and constructed that eliminate dog odor and offer solutions to many other kenneling problems. Whelping of several hundred litters of beagles indicates that the dam attains full maturity at three years of age. Records also show that about 20% of all pups die before weaning and that two-thirds of these are birth losses. Pups attain puberty between 10 to 12 months of age, which is a growth rate 10 times faster than man.

FOR MORE THAN 30 years, selenium has been known among scientists as a rare and versatile, but also toxic mineral, causing poisoning to livestock in the United States as well as other parts of the world.

Only 20% of the barley seed lots sampled in a two-year, 17-county survey—as reported in this study—met standards required of California certified barley seed. Fifty-four per cent of the samples contained excessive weed seed and 12% contained secondary noxious weeds. Forty per cent of the samples also contained an average of 72 seeds of other crops per pound of barley seed. Twenty-six per cent of the samples germinated less than 90%. Forty-nine per cent of the samples averaged 7.1% trashy, inert material and 43% were found to contain varietal mixtures.

The green peach aphid is attacked by a number of beneficial insect species which keep aphid densities suppressed much of the time. Increased resistance of the aphids to many commonly used organic phosphate insecticides has occurred. Intelligent use of selective insecticides, which destroy the pests but spare many beneficial insects, is one of the best approaches for green peach aphid control on peppers, according to these tests.

The primary benefit of nitrogen fertilization to grassland areas of north coastal California was the increase in production of forage during the winter season when grass was short and legumes grew very slowly. According to these tests, not more than 80 pounds N per acre should be applied since near maximum forage yields were produced at this rate and little increase in winter production resulted from additional amounts. However, carryover into the second year was measurable only with applications of the 160-pound maximum used in these tests on two soil types. Protein percentages in the nonleguminous plants increased with increasing N application rates during the vegetative stage, but at maturity, the nitrogen percentages in these plants were less where 40 pounds of N per acre had been applied than on the non-treated check plots. The 160-pound rate increased the protein percentage in mature plants. Total nitrogen uptake of all forage species combined, increased during the winter with increasing rates of N applied. However, uptake on the unfertilized plots during the warm spring months, when the clovers grew rapidly, was about the same as that on plots fertilized with 40 pounds of nitrogen per acre.

BLUE OAK on the woodland grass areas of Tulare County are frequently not killed by burning. Such treatments are effective in killing much of the non-sprouting brush, but sprouting species such as poison oak rapidly recover. There is always the danger that fires will escape onto other properties, including the National Forests and Parks. For these reasons, interest in methods of control in addition to fire have existed for many years in Tulare County.