Insecticide Efficacy Against Blue Alfalfa Aphid, 2014a

The objective of the study was to evaluate the efficacy of the new and old insecticidal compounds used against BAA on alfalfa grown for hay production under desert growing conditions. A field study was conducted during the spring of 2014 at the UC Desert Research and Extension Center. A stand of alfalfa, ‘CUF 101’, was used for the experiment. The experimental design was RCB using four replicates with twelve insecticidal treatments and an untreated check. Plots measured 13.33 ft by 50 ft and insecticide treatments were applied on 5 Feb 2014, using a ground broadcast application with a handheld CO ₂ backpack sprayer with a boom covering a 13.33 ft swath operated at 30 psi, delivering 20 gpa through 10 (TJ-80015) nozzles. The BAA population was measured in each plot with a standard 15-inch diameter insect net consisting of ten 180 ^o sweeps; means reported in the tables are per sweep. Pre-treatment samples were collected on 4 Feb, and indicated as 1 DPT in the table. Post-treatment samples were collected on 10 Feb or 5-days after treatment (5 DAT), 12 Feb (7 DAT), 19 Feb (14 DAT), and 26 Feb (21 DAT). Sweep samples were bagged, labeled, and frozen for later counting of BAA in the laboratory. Data sets were analyzed using a two-way ANOVA and means separated by Tukey’s Honestly Significant difference Test; ( P  ≤ 0.05).

The 2014 BAA levels were typical of what is found in Imperial Valley alfalfa during early-Feb to mid-Feb and increasing. There were no differences in BAA densities among plots on 4 Feb, 1 DPT ( Table 1 ). All insecticide treatments, except Cyclaniliprole 50SL at 16.4 and at 20 fl oz/acre, significantly reduced BAA densities compared with the untreated check at 5 DAT. All insecticide treated plots had BAA means that were significantly lower than the BAA mean for the untreated plots at 7 DAT, except Lorsban Advanced, and Cyclaniliprole 50SL at 16.4 and 20 fl oz/acre. All insecticide treatments resulted in significantly lower BAA densities compared with the untreated check at 14 DAT, except Cobalt Advanced, Cyclaniliprole 50SL at 16.4 and 20 fl oz/acre and Assail 30WG at 7 oz/acre. Only plots treated with Transform WG at 1.5 oz/acre had fewer BAA than the untreated plots at21 DAT. All insecticide treated plots had PTA for BAA that were significantly lower mean than the untreated check, except Cyclaniliprole 50SL at 16.4 and 20 fl oz/acre. None of the insecticide treatments resulted in any injury to the alfalfa plants. This research was supported by industry gifts of products and research funding.

Author notes