Impact of Verimark, Radiant SC, and SPE-120 Against Cabbage Maggot in Radish, 2019

In 2019, an efficacy trial located in Aurora, OR, at the North Willamette Research and Extension Center was conducted to evaluate selected insecticides targeting Delia radicum in radish. Plot size was three rows wide by 30 feet in length with 15 inches between rows and a 1.5-inch spacing within rows. Study was structured as a randomized complete block with four replications. Insecticide treatments included SPE-120 as a seed treatment, Verimark 1.67SC as an in-furrow treatment, Radiant SC and SPE-120 as directed sprays, and an untreated check. Except for the SPE-120 seed treatment, all seeds were treated with the fungicides Apron XL (0.64 fl oz/100 lb seed), Maxim 4FS (0.64 fl oz/100 lb seed). And Dynasty (0.383 fl oz/100 lb seed). The SPE-120 seed treatment did not receive fungicide because it is composed of the fungus Beauveria bassiana and including fungicides would have affected treatment efficacy. Seeds were planted 30 April, and Verimark was applied at 13.5 fl oz/acre using a vacuum seeder modified with a CO₂ delivery system to deliver in-furrow drench applications. Seeds treated with SPE-120 received 500 mg dry formulation per 100 g seed. Directed spray applications were made at prescribed postemergence intervals with a CO₂ backpack sprayer calibrated to deliver 26.4 gallons of water per acre at 25 psi through a hand-held boom with three TeeJet 8003VS flat fan nozzles on a 15-inch spacing. Emergence was apparent at 3 d after seeding (DAS). Radiant SC was applied twice, at the rate of 10 fl oz/acre each time, at 3 and 17 DAS. SPE-120 was applied at 2 fl oz/acre at 13 DAS.

Radish emergence was evaluated at 21 DAS by counting the number of emerged radish plants in each of two 1 m row sections in each plot. Early sampling was conducted at 30 DAS by randomly selecting 15 plants from each plot and rating each for cabbage maggot feeding damage. Results are reported as an average percentage of radishes per plot with feeding damage. Final harvest was conducted at 37 DAS, with 30 plants per plot washed and evaluated for damage by cabbage maggot larvae. Results are reported as the average percentage of radish bulbs per plot with tunneling damage. No phytotoxicity was observed in any treatment. Data were subjected to ANOVA. No significant differences were observed among treatments at any sample date. Treatment means for each rating of each treatment are provided in Table 1.¹

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