Efficacy of Selective Insecticides Against Southern Armyworm and Beet Armyworm in Bell Pepper, 2000

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P. A. Stansly and J. M. Conner
University of Florida/IFAS
Southwest Florida Res. and Ed. Center
2686 State Road 29 North
Immokalee, Florida 34142-9515
Phone: (239) 658-3427
Fax: (239) 658-3470
Email: pas@ifas.ufl.edu

BELL PEPPER: Capsicum annuum (L.) ‘Boyington Bell’
Southern Armyworm Spodoptera eridania (Cramer)
Beet Armyworm Spodoptera exigua (Hübner)

Beet armyworm and southern armyworm are the principal lepidopteran pests of pepper in south Florida. Newly registered selective insecticides are providing an alternative to broad-spectrum materials that requires testing. Greenhouse-raised pepper plants were transplanted on 11 Sep at 10 inch spacing in single rows on 4 drip-irrigated beds, 32 inches wide and 240 ft long on 6 ft centers. Beds had been fertilized by incorporating 800 lbs/acre of 5-16-8 dry fertilizer and fertigated with an additional 175 N and K /acre through Netafim™ drip tape with 12 inch emitter spacing. Beds were fumigated when formed with a 67/33% mixture of methyl bromide/chloropicrin at a rate of 300 lbs/acre, and covered with white polyethylene film. Each pair of beds was separated by an additional bed of bell pepper planted on 11 Sep and left untreated to serve as a source of inoculum. Each bed was divided into plots 48 ft long to which 6 treatments were assigned in a randomized block design with 4 replications. A pre-treatment count of 20 plants per plot on 29 Sep showed 3 % of the plants with armyworms present (75 % BAW). Treatments were initiated on 29 sep and applied 6 times on 29 Sep, 17, 25 Oct and 1, 14, 22 Nov using a high clearance sprayer with two vertical and one horizontal boom, each fitted with one ceramic "yellow" Albuz ATR tm hollow cone nozzle for a rate of 33 GPA at 200 psi. Six weekly evaluations were made beginning 20 Oct on 20 plants/plot. Total numbers of beet armyworms and southern armyworms/plant were recorded by size of larvae. An evaluation of plant damage was also made on the same plants where 0 = no damage, 1 = 1 - 2% damage, 2 = 2 - 5% damage, 3 = 6 - 10% damage, 4 = 11 - 30% damage, and 5 = > 30% plant damaged. Two Scentry wing type of phermone traps were used to monitor BAW adults. Weekly captures numbered 1-2 except for the week of 8 Oct when 5 were caught. Fruit from 30 feet of row ( 36 plants) was harvested, counted and weighed on 6 Dec.

The pressure from either species of armyworms was light even though there was heavy southern armyworm pressure in tomato approximately 55 feet away. Early pressure from BAW was controlled in both Avaunt/Spintor rotation plots and at the high rate of Avaunt alone. There were no BAW egg masses in the control or low rate of Avaunt plots. Later SAW were observed on untreated plants and plants treated with the high rate of Avaunt although the latter were controlled before they could move from foliage to fruit. Fewer worms were observed treated plants regardless of treatment compared to untreated plants. There were no treatment effects on yield due to light pest pressure.

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