Browsing Vegetable Report 2004 by Subjects
Now showing items 1-4 of 4
Foliar Activity of Assail®, Fulfill® and Flonicamid® on Aphids in Leafy VegetablesSeveral small-plot studies were conducted in the spring of 2004 to compare the residual efficacy of several new reduced risk insecticides against aphids infesting desert head lettuce. In 4 head lettuce trials and one broccoli trial, economic aphid control was consistently achieved following foliar applications with flonicamid and Assail. These compounds provided good knockdown of aphids when applied relatively early in lettuce plant development and aphid population growth. Fulfill was less consistent and performance was reliant on correct spray timing. Collectively, the chemical attributes and biological activities of Fulfill, Assail and flonicamid make them extremely attractive for implementation into an aphid management program.
Impact of Planting Date on Aphid Infestations and Contamination in Head LettuceThe influence of planting dates on aphid population growth in head lettuce was measured over a 5 year period to identify planting windows during the season when lettuce is at risk from aphid infestations. Small, untreated 0.2 acre plantings of head lettuce were established beginning in October with final harvest occurring in April. Plant samples were conducted weekly to estimate the numbers of aphid per plant. Based on these studies, planting date and temperature likely has a strong influence on seasonal abundance and damage caused by aphids. Green peach aphid was the least abundant aphid during the 5 year period, and foxglove aphids appear to be increasing in abundance over the past 3 years. All aphid species have the potential to economically contaminate lettuce, particularly in the November and December planting windows.
Insect Pests in Yuma Winter Vegetables: Review of the 2003-2004 SeasonInsect pest populations seemed to be exceptionally abundant on our desert vegetable crops this past growing season. It is difficult to explain why some insect populations occurred in larger numbers this year, but the weather we experienced may have had a significant role. Hot, dry weather in the early fall and spring, coupled with moderate winter temperatures provided ideal conditions for some insect pests.
Seasonal Abundance of Western Flower Thrips Populations in Desert Head LettuceStudies were conducted from 2001-2004 to examine thrips abundance in multiple lettuce plantings throughout the growing season. Head lettuce was sampled periodically on untreated, 0.25 acre plots at various intervals from early September through March. Results clearly showed that thrips reproduction and development on desert lettuce is largely influenced by temperature. Thrips adults and larvae populations within each planting were consistently most abundant on lettuce planted in November and December where temperatures averaged 60-65 degrees F during the spring. Population development was at its lowest level in the October plantings, particularly during the cooler winter periods. This study demonstrates that western flower thrips populations are capable of reproducing and developing large densities on head lettuce under winter and spring growing conditions in the desert.