Control of Southern Armyworm and Beet Armyworm in Bell Pepper with Biopesticides, 1999

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P. A. Stansly, J. M. Conner and D.R. Peach
University of Florida/IFAS
Southwest Florida Research and Education Center

BELL PEPPER: Capsicum annuum (L.) ‘Red Knight'
Southern Armyworm Spodoptera eridania (Cramer)
Beet Armyworm Spodoptera exigua (Hübner)

Biopesticides have many advantages over conventional insecticides for control of crop pests including Spodopetera spp. such as short re-entry and pre-harvest intervals, low non-target toxicity and few use restrictions. However, sufficient efficacy must be demonstrated to assure adequate crop protection. This trial tested the efficacy of 2 different formulations of Bt ‘kurstaki’ and 2 nuclear polyhedrosis viruses (NPV), one (Spod-X LC) specific to BAW and the other with a broader host range among Lepidoptera. Greenhouse-raised ‘Red Knight’ pepper plants were transplanted on 29 Sep at 10 inch spacing in single rows on 2 sets of 3 plastic mulched beds, each set separated by an 18 ft roadway. Each bed was 32 inches wide and 240 ft long on 6 ft centers and fertigated through Netafim™ drip tape with 12 inch emitter spacing. The center bed in each set of 3 was left untreated to serve as a source of innoculum. There remaining 4 beds were divided into plots 48 ft long to which 5 treatments were assigned in a randomized block design with 4 replications. Treatments were applied 8 times on 26 Oct, 4 and 10 Nov, 1, 7, 15, 22 and 29 Dec using a high clearance sprayer with two vertical and one horizontal boom, each fitted with ceramic "yellow" Albuz ^tm hollow cone nozzles. The rate in Oct and Nov was 32 gpa with one overhead nozzle and one in each drop boom. The rate was increased to 55 gpa in Dec with the addition of 1 more nozzle on each drop boom. The pressures was 200 psi and a nonionic sticker, Latron B-1956 Spreader Sticker, was tank mixed at a 2 % rate. An average 0.1 armyworm larva/plant (67 % beet armyworm) was observed in a pre-treatment count of 25 plants/replication on 25 Oct. Ten weekly evaluations were made beginning 1 Nov 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. Fruit from 20 feet of row ( 25 plants) was harvested, counted and weighed on 21 Dec and 04 Jan from each plot.

Early pressure was low and only from beet armyworm (BAW). No BAW were observed after the second post-treatment evaluation. Southern armyworm counts increased significantly in mid Dec. Counts of all larval stages and damage ratings were significantly higher on untreated plants than on all other treatments. Plants treated with Javelin had fewest larval but was not significantly less than Lepinox in the medium range. Total larvae grouped the Bts in the lowest category, followed by the NPV and then the untreated control. Damage ratings separated all treatments except for the two NPVs. Most SAW were observed when fruit had nearly matured but there was still significant treatment effects for number and weight of marketable fruit between the Bt treatments and the untreated plots with NPV treatments intermediate and not significantly different from any other treatments.

Florida Agricultural Experiment Station Journal Series No. N-02005.

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