Efficacy of Insecticides Against Chilli Thrips (Thysanoptera: Thripidae) in Containerized Distylium in Commercial Nursery, 2018

A trial comparing the efficacy of insecticide treatments against chilli thrips was conducted in a potted Distylium plants (3 gal) in a commercial nursery at Dearing, GA. Ten replicates of each treatment were assigned to potted plants according to a randomized completely block design. The details on insecticide products and rates are shown in Table 1. First broadcast-spray and drench applications of insecticides were made on 6 Jun 2018 followed by a second application on 13 Jun 2018 (7 d after first application). The foliar applications were made using CO₂-powered single boom (one nozzle) handheld sprayer on the potted plants with two passes from the either sides of the plant. The water volume used in both the applications was 100 gal per acre delivered at 30 psi. For drench treatments, 400 ml of the insecticide solution was added to the soil media per pot. Beat-trays were used to sample chilli thrips populations. Plants were sampled between 11:00 a.m. and 2:00 p.m. by making five strikes per plant with the lid of a Rubbermaid container (14 × 6 × 5 inch [deep]) into a tray container. A yellow sticky card (8 × 5.5 inch) was placed inside and trays were covered with clear plastic wrapper and transported to the laboratory for evaluation. Sampling was done at 7 d after the first application and then 7, 14, 21, and 28 d after the second application. The number of chilli thrips on each sticky card was quantified using a microscope.

Chilli thrips data were subjected to PROC GLIMMIX (SAS Institute 2012, Cary, NC) with log link function and distribution as negative binomial.

Seven days after the first foliar application, the number of chilli thrips was significantly lower in Mainspring- and Conserve-treated plants than those in the nontreated control treatment (Table 1). Among drench treatments after the first application, the number of chilli thrips was significantly lower in Altus- and Zylam-treated plants than those in nontreated control treatment. Seven days after the second foliar application, none of the foliar-applied insecticide treatments was significantly different from nontreated control. Among drench application, Mainspring- and Zylam drench–treated plants showed significant suppression of the number of chilli thrips compared with nontreated control plants. The number of chilli thrips was not significantly different among treatments for both foliar and drench treatments after 14, 21, and 28 d after second application.

This project was funded by University of Georgia, Center for Nursery Research grant.