Insecticide Efficacy Against Aphids on Artichoke, 2014 *

The objective of the study was to evaluate the efficacy of insecticides for control of aphids on artichoke under desert growing conditions. An established stand of artichoke (Imperial Star) at the University of California Desert Research and Extension Center, El Centro, CA, was used in the experiment. Plots were 1 bed (3.33 ft) by 25 ft with a 2-ft buffer between blocks. Included were four foliar insecticide spray treatments and an untreated check in an RCB design experiments with five replicates. Insecticidal compounds, formulations, and application rates are provided in the tables. Insecticide treatments were applied on 10 March 2014 using a handheld CO ₂ propelled sprayer three TeeJet 8002VS nozzle/bed, delivering 31.4 gpa at 30 psi. Ten leaves were extracted at random from artichoke plants in each plot, bagged, and labeled for later extraction of alate and apterous aphids. Extractions were achieved by washing the aphids from plants with a mild detergent, then filtering the aphids from the diluent, and storing the aphids in glass vials of 70% EtOH labeled with the extraction dates and plot numbers for identification and counting on later dates. Alate and apterous aphid means in the tables are reported as aphids per plant. Data were analyzed using analysis of variance. Differences among means on each sampling date were determined using the LSD test (α = 0.05).

There were no differences among the treatments for alate aphids or the apterous aphids for any of the treatments on any of the sampling dates or for the alate and apterous aphid posttreatment averages ( Tables 1 and 2 ). Because the artichoke leaves were very large, there were very high numbers of aphids, but the distribution appears to have been clumped and the RCB design of the experiment did not appear to account for all of the variation between and among the treatment plots. There also appears to have been a lack of efficacy for all of the insecticide treatments that may be due to lack of insecticide penetration deep into the artichoke plant canopy. The artichoke plants were very large with harvestable floral buds at the time of insecticide applications. No phytotoxicity symptoms were observed following any of the insecticide treatments.

Author notes