All Issues

Brown surface discoloration damage to Bartlett pears shipped in jumble-packed fiberboard cartons—during the 1955 season—caused complaints in eastern markets, particularly following rail shipments. Consequently, laboratory tests were conducted during the 1956 pear season to obtain information on the nature of the discoloration and its prevention.

Late fall applications of nitrogenous fertilizers to California foothill ranges have consistently hastened the growth of native forage plants both in fall and spring, resulting in a winter forage production which may be advanced as much as two months. Also, the herbage produced by fertilized plants is not subject to frost damage to the same extent as that produced by unfertilized plants.

Previous experiments have demonstrated the feasibility of prebloom sprays for control of European red mite eggs.

Water table conditions especially were studied in the Guadalupe area during an investigation designed to obtain more information about the physical conditions affecting plant growth in the lower Santa Maria Valley.

Leaf burn and defoliation on the lower part of the tree found in the fall of 1955 in several citrus orchards in Riverside County—recently converted to the lowhead type of sprinkler irrigation—led to a preliminary survey of citrus and avocado orchards in the county. Leaf burn on the skirts of sprinkled citrus orchards was found in the Hemet, La Sierra, Corona, and Coachella Valley areas. Varieties included grapefruit, Valencia and navel orange, and tangerine. Sprinkled avocado orchards did not show the marked burn on the tree skirts found in citrus. In some cases, a white salt residue was found on the citrus leaves on the portion of the tree that was wetted during sprinkling. The upper part of the tree which received no water spray during irrigation showed no burn or defoliation.

Relatively large losses of magnesium from the soil in the long-term fertility trial plot at Riverside—during a 28-year period—were revealed by analysis of soil samples taken in 1927 and in 1955. The losses of magnesium increased with increase in amount of fertilizers and gypsum added to the soil.

The fig mite—Aceria ficus (Cotte) — was shown to transmit fig mosaic virus in experiments set up to determine whether or not mosaic symptoms would persist on fig plants in the absence of fig mite infestations.

Average production of southern California oranges dropped from 370 to 265 field boxes per acre—for navels—and from 290 to 265 field boxes per acre—for Valencias—over a 12-year period. Many individual orchards in Los Angeles, San Bernardino, and Orange counties—the three areas most seriously affected—showed a production decline of as much as 100 to 250 field boxes per acre during the same period.