Zone Management Approaches in IPM of Tarnished Plant Bug in Midsouth Cotton.

Crop protection decision-making has grown increasingly complex as accessibility and implementation of spatial technology and site specific management have become more established on U.S. farms. In the Midsouth, zone management practices for agronomic inputs  are prevalent on cotton [Gossypium hirsutum] farms; however, use of site-specific approaches for insect control are lacking. This report summarizes field validation of a simple zone approach for insect pest control for tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), a key pest of Midsouth cotton. Zone management for insecticidal control termination was evaluated in irrigated and rainfed management zones in a center pivot irrigated field over four growing seasons in Northeast Arkansas. The on-farm study was a replicated strip trial with three insect control spray treatments (broadcast, zone, or untreated check) across two management zones (plants under center pivot irrigated “circles” or plants in rainfed “corners”).  Strips were 28 rows wide across the length of the commercial field (1/2 mile). Crop monitoring (weekly measures of nodes above white flower (NAWF)) was used to determine date of physiological cutout - flowering date of last effective bolls - in the two zones. Insect monitoring included weekly drop cloth sampling.  Final, late-season insecticide applications in broadcast and zone treatments were timed to when last effective bolls had reached the final stage of crop susceptibility (250 heat units (DD60s) after cutout (NAWF=5)). Plants in rainfed zones reached cutout 4 to 21 days earlier than irrigated plants, depending on the year, and in the zone management and check treatments, these plants received no further protective sprays. Yield data were acquired with yield monitors on the cooperating farmer’s cotton pickers. No yield penalties were associated with following NAWF-based crop termination rules in management zones compared to conventional broadcast control. These data support adoption of a zone management approach for late season crop protection from plant bugs. With this approach, producers with auto-guidance technology can employ map-based applications of crop protectants to control damaging levels of insect pests only in those areas of the field with plants still vulnerable to late season infestations. Adoption of this approach will allow producers to offset rising protection costs (there was a 13 % reduction in cost for 1 to 2  late season insecticide applications)  as well as reduce environmental impact of insecticide applications at the edge-of field (demonstrated using the Field Print Calculator).