California Agriculture, October 1967
Volume 21, Number 10
Picker shown with mask, respiration meter, and connecting hose used during orange picking tests to determine human energy costs.
Human energy costs of picking oranges
by C. E. Schertz
Results of investigations of human energy expended by orange pickers show that pickers are 25% more efficient when picking fruit from the ground than during general picking. Picking fruit from a ladder is not appreciably less efficient than general picking. ladder-carry and setting require twice the energy per unit of time as general picking.
Forage and protein production by subclover-grass and nitrogen-fertilized California grasslands
by Milton B. Jones
Range grass areas including stands of subclover produced forage yields equal to those from nitrogen-fertilized annual grasslands in a moisture-deficient year in northern California, and more forage was produced in a moisture-adequate year, according to this study. Stands of subclover and grass produced forage yields equal to those from California annual-type grasslands fertilized with 45 to 90 kg of nitrogen (N) per hectare (45 kgN/ha = 40 Ib/acre), in a moisturedeficient year (when rains began and ended in March). In a moisture-adequate year (with rains commencing in early October and ending in May), subclover-grass stands produced more forage than did resident grasslands fertilized with 179 kg N per ha. Nitrogen fertilization was found to contribute most to forage production during the winter period. Second- and third-year stands of subclover also showed production increases early in the season, but made the greatest gains in April and May.
Pre-emergence herbicides for weed control in lettuce
by H. Agamalian, A. Lang, H. Ford, H. Kempep, J. Lyons, E. Stilwell, O. McCoy, F. Robinson
California lettuce growers spend $11,620,000 per year for weed control. Although mechanical cultivation will control weeds in the furrow and between rows, weeds in the seed row are still controlled by hand chopping at approximately $20 to $60 per acre. With increased costs and difficulties of obtaining qualified field labor, more and more emphasis has been put on mechanical thinning and chemical weed control. Inasmuch as the more successful mechanical lettuce thinners do not distinguish between plants in general, weeds cannot be tolerated in the seed row and therefore can be eliminated most economically by selective chemical weed control. Some satisfactory weed control over the years has been obtained with the use of Vegadex and IPC with certain weed species. Several new herbicides have promised a wider spectrum of weed control, and are being used to a limited extent for weed control in lettuce. Balan and Dacthal were used last year commercially and Prefar was used in experimental plantings. Balan was recommended this year by University of California for weed control in lettuce.
New spider mite poses threat to California's solarnaceous crops
by E. R. Oatman, O. Fleschner, J. A. McMurtry
A new spider mite found inuthern California poses a threat to solanaceous crops. Preliminary studies in date that the species is highly destructive to tomatoes, potatoes, and eggpla-nightshade is a preferred native host and Black serves as a useful indication for determining distribution of the mite pest.
Horn fly and grub contzeol on beef cattle… testing several new insecticides
by W. H. Johnson, E. C. Loomis
A 75% reduction in horn fly populations lasted from two to four weeks following trial spray applications of insecticides in June, for two to six weeks following August treatments, and for the remainder of the fly season with most of the September grub control treatments. During the entire trial, most treatments kept horn fly populations below 100 flies per animal for five to six weeks after treatment. Grub control was excellent with all treatments, ranging from 96% to 99% control. Both common and northern grub infestations were effectively reduced. The split dose of Ruelene 8R provided excellent grub control as well as satisfactory horn fly control from August to the end of the fly season. There were no adverse effects observed on any animals treated during this Study.
Early aphid control increases beet production
by W. H. Lange, F. J. Hills, R. S. Loomis, J. Kishiyama
Sugar yield was increased 30% in 1965 and 20% in 1966 by aphicide applications to protect young plants from virus-carrying Ophids.
Effects of different rootstocks, and degree of psylla infestation on leaf curl in young pear trees
by W. H. Griggs, D. D. Jensen, B. T. Iwakiri, J. A. Beutel
Differences in pear varieties, source of scion wood, and kind of rootstock had little effect on the incidence of leaf curl in these tests. Psylla are evidently the vectors of curl and there appears to be little hope of controlling the disease through selection of propagating material, unless psylla are excluded. If not infected in the nursery row, many pear trees may quickly become infected in the young orchard even under the best commercial spray program.