Calag Archive

Trials with western flower thrips confined on growing safflower buds for 34 days demonstrated that the buds are able to tolerate numbers of nymphal thrips averaging as high as 75 per bud (when cages were initially injected with 10 adults per bud) without any significant drop in seed production. However, infestations that had started with 20 or 40 adults per bud did significantly decrease the number of good seed heads produced, the number of seeds per head, and the total yield. Trials with lygus bugs, Lygus hesperus Knight, indicated that the threshold of economic damage to the safflower crop was exceeded when the ratio of bugs to buds exceeded 1-to-8. Significant decreases in yield criteria were obtained when the bug-to-bud ratios were adjusted to 140–4 or higher. A new stripe, or thin-hulled, variety appeared to be more susceptible to injury by lygus bugs than the variety U. S. 10.

It has been observed in previous studies that Easter lilies grow taller at lower light intensities. From data recently collected at the Los Angeles campus, it was also found that closer spacing is equivalent to lower light intensity insofar as height is concerned. The data summarized in the graph indicate that plants from commercial-size bulbs were of minimum height when 100 sq inches or more were allowed per plant. At higher light intensities, this critical value would be expected to be lower and at lower intensities, higher.–Harry C. Kohl, Jr., and R. L. Nelson, Department of Landscape Horticulture, University of California, Davis.

These studies show that the distribution and amount of litterfall under bigtree and pine canopies is such that bared areas will be well covered within a year's time. On the basis of amount of litter produced and ground covering potential, the pines are more desirable associates for bigtrees than are white fir or incense-cedar. Also, pine needles provide excellent fire-carrying fuels where prescribed burning is used to maintain low fire hazard conditions.

VARIOUS FIBER CONTAINERS are being successfully used for growing ornamental plants in nurseries, and some of these materials are now being used in vegetable crop production. Opportunities exist to increase their use in vegetable crop transplanting, particularly for special soil problems or under unique climatic conditions. However, several new problems arise in using fiber containers for vegetables that are not usually found with existing methods of bare-root transplanting. The problems begin with the initial stage of plant growth in the greenhouse and continue through maturity.

Field experiments for alfalfa weevil control conducted in Siskiyou and Lassen counties during 1964–65 indicate little likelihood of replacing the no longer recommended cycladiene insecticides (such as heptachlor or dieldrin) with other materials for dormant season application. However, several new insecticides, applied as sprays for larval control on the growing crop, were found superior to spray materials now in use. This is a progress report of research; only a few of the materials mentioned in the text and tables are registered or recommended by the University of California. See U.C. Pest and Disease Control Guide For Alfalfa Hay, Leaflet 85, for recommendations.

GROWERS OF EASTER LILIES have recently been troubled by yellowing of plant foliage. These experiments were conducted to determine whether pesticides used for aphid control might be the cause of this injury. The tests were conducted in commercial greenhouses on potted lilies that had been "forced" for Easter. Full coverage pesticide sprays were applied with a hand sprayer.

Limited studies with water temperatures, as reported in this article, indicate soil temperatures are reduced for short periods of time with possible effects on yield where crops are irrigated frequently with cold water.