Typescript. / Digitized by Kansas Correctional Industries

Call number: LD2668 .T4 1956 C73 / Master of Science

Call number: LD2668 .T4 1956 M32 / Master of Science

Call number: LD2668 .T4 1958 Q85

Call number: LD2668 .T4 1959 K73

Call number: LD2668 .T4 1965 S979 / Master of Science

Commercial and experimental insecticides were evaluated for their ability to control diamondback moth (DBM) on green cabbage in Yuma, AZ. At early to mid-heading, all the insecticides evaluated appeared to offer similar control. However, on large, full sized cabbage, Asana, Alert, Lannate, Success and S-1812 offered the best DBM control, while Lorsban, Proclaim and Intrepid appeared weak. Unlike other areas of the U.S., DBM in Yuma still appears to be highly sensitive to a wide range of insecticide chemistries.

Knack was evaluated for its potential for regulating aphid populations in green leaf lettuce. However, Knack did not appear to be a viable control option, and probably did not work due to an inability to deliver the material where the aphids were on the underside of the lower leaves. A soil injection treatment of Admire at planting, and a foliar standard of Warrior + Endosulfan applied at the initiation of aphid colonization and again 14 later, were highly effective treatments.

The timing and application methods of new insecticide chemistries for aphid control were compared to imidacloprid in several studies in 1998 and 1999. Foliar applications of Fulllfill, Aphistar, Actara and Acetamiprid appear to provide an alternative method of controlling aphids on lettuce comparable to prophylactic applications of Admire. Timing applications as aphids began to colonize was critical for preventing head contamination at harvest. In addition, at planting and side dress soil applications of Platinum provided aphid control comparable to Admire. Residual activity of the new foliar alternatives appeared to differ depending on spray timing relative to aphid density and plant stage. These studies suggest that more than one application of the foliar products will be necessary to adequately suppress aphid contamination in heads. Evaluations of thiamethoxam suggest that it is more mobile in the soil than Admire and may be a candidate for side dress applications for aphid management.

Several small plot studies were conducted during the spring of 1999 to examine the population growth, distribution and control of the lettuce aphid on romaine. The lettuce aphid population developed to greater numbers more quickly and spread among plants more rapidly when compared with other aphids species under late spring growing conditions. Most of the lettuce aphids sampled were found on the hearts of the plants rather than the frame and wrapper leaves. Our preliminary efficacy studies suggest that foliar sprays, when timed properly and with proper coverage, can provide adequate control of the lettuce aphid for up to 14 days. Furthermore, significant suppression of apterous lettuce aphid populations was observed in plots where pyrethoid treatment were sprayed for thrips control. The implications of these results for future research and management of lettuce aphids in desert lettuce is discussed.