A number of chemical compounds have been field evaluated as potential pesticides for control of insects on lettuce over the past several years. The important pests of fall planted lettuce being the cabbage looper, beet armyworm and corn earworm. In addition to the chemical compounds, the disease organism Bacillus Thuringiensis was used. It is slower in acting, but can be quite effective, particularly against the cabbage looper. Some of the chemical compounds which have been evaluated and are now available commercially are Sevin, Dibrom and Bidrin. This evaluation will continue as new and possibly more effective materials are made available.

Research work aimed at developing a selective mechanical harvester for crisphead lettuce was initiated in 1961. During the course of the project, two experimental machines were constructed. Commercial development of the harvester was assumed by Lockwood Grader Corporation in 1964 under terms of a contract between Lockwood and the Arizona Research Foundation. Lockwood is now in the process of constructing a four row prototype harvester that will be capable of harvesting 1.5 acres of lettuce per hour.

No description available.

A study was made of the characteristics of harvested lettuce heads in Arizona during the 1964-65 season. Information on size, weight, firmness and number of wrapper leaves of each head sampled was collected and set up for analysis. No results were available at the time of this progress report.

No description available.

A series of studies on lettuce fertilization have been carried out over the past few years. Fertilizer applications increased yield through increased head size and did not affect the number or quality of harvested heads. The lower rates used were as effective as the higher rates. Nitrogen and phosphorus fertilization generally increased the nitrate and phosphorus content of the various plant parts selected for analysis.

No description available.

Lettuce stand problems in desert production areas are, in many instances, related to high seedbed temperatures and the use of seed coatings. We evaluated the use of fusicoccin and other growth regulators to improve the performance of naked and coated lettuce seeds at high temperature. Treatment of both naked and coated seeds with fusicoccin markedly increased the rate and total emergence of seedlings incubated at 35 °C for 10 hours alternating with 23 °C for 14 hours.

No description available.

Gypsum was applied preplant on spring lettuce at rates of zero, 2 tons per acre, and 4 tons per acre. There were no significant differences in carton yields or in carton weights. Postharvest soil analyses showed that the application of four tons of gypsum per acre significantly increased the calcium and magnesium levels in the saturated paste solution. There were no significant effects of gypsum application on ESP and SAR values, nor in pH or sodium concentrations.