Tomato Miticide Trial, 2014 *

This study was conducted at the Mountain Research Station in Waynesville, NC. Six-week-old ‘FL-47’ tomato transplants were set on 28 May on black plastic mulch with drip irrigation. Plots consisted of single 20-ft-long rows on 10-ft centers. Plants were spaced 1.5 ft within rows and treatment rows were separated by a nontreated row of tomatoes. Each treatment was replicated four times and arranged in an RCB design. Tomatoes were staked and strung as needed and sprayed with a standard fungicide program. Two days before planting, transplants were infested with TSSM while in transplant trays. Miticide treatments are shown in Table 1 . With the exception of the Levo and PFR-97 treatments, which were applied on a preventive weekly schedule beginning on 8 Jul when TSSM densities averaged 0.2 mites per leaflet, initial treatment applications were made at a threshold of approximately 3 mites per leaflet. A second application was applied if or when mites reached approximately 10 per leaflet. With the exception of the Athena and Gladiator treatments, all treatments were sprayed with a similar insecticide program consisting of alternating weekly applications of Coragen (5 oz/acre), Radiant (6 oz/acre), and Avaunt (3.5 oz/acre), with one application of Admire (1.5 oz/acre) applied for aphids on 5 Aug. The Athena and Gladiator treatments were sprayed weekly with Brigade 2EC (6.4 oz/acre) and Mustang Maxx 0.8EC (4 oz/acre), respectively, which was not included when Athena and Gladiator applications were made.

All treatment applications were made with a CO ₂ backpack sprayer equipped with a three-nozzle wand used to apply materials to both sides of treatment rows—i.e., materials were effectively applied through six hollow cone nozzles per row at 30 psi. Levo and PFR-97 applications on 8 and 14 Jul were made at 50 gpa, while miticide treatments made on 21 Jul were at 70 gpa, and all remaining applications were at 100 gpa. Mite populations were monitored by observing 10 leaflets per plot with a 10× visor lens and counting all motile TSSM. Data were analyzed using a two-way ANOVA and means were separated by LSD ( P  = 0.05). Data were transformed before ANOVA using either square root or log transformation, but results in tables are shown as back transformations.

The Brigade applications made previous to the Athena treatment were effective in suppressing TSSM populations, which is why Athena was not applied until 5 Aug. The combination of Brigade and one Athena application helped to maintained TSSM populations at very low levels, never exceeding 5 mites per leaflet. Among those treatments applied on 21 Jul, Gladiator, Acramite, and Nealta + Cohere + Dimethoate had the most effective knockdown effect, while Nealta was less effective when applied alone versus with Cohere or LI-700. Acramite appeared to have the strongest residual activity. Among the products applied preventively with multiple applications, Levo suppressed mites and delayed the buildup of populations, while PFR-97 did not differ from the check on any sample date. It should be noted that PFR-97 is an arthropod fungal pathogen, and thus is likely sensitive to some of the maintenance fungicides applied weekly to plots, including mancozeb, chlorothalonil, and strobilurin. Also, Levo, which contains the active ingredient oxymatrine from the roots of the plant Sophora flavescens , exhibited phytotoxic effects to tomato foliage when applied at the 50 gpa rate, or a concentration of formulated product of 0.65% (2.54 oz product per 3 gal water). Phytotoxicity was not observed later in the season when product was applied at 100 gpa, or a concentration of 0.33%.

Author notes