Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 12/1/2001
Publication Date: N/A
Citation: Interpretive Summary: The tarnished plant bug (TPB) is a major pest of cotton. TPB and western plant bugs caused an estimated loss of 300,000 bales in 2001. In addition to yield loss, TPB can cause delays in crop maturity. Many times, Mid South cotton can compensate for delayed maturity during a long growing season. However, northern parts of the Mid South typically have less time for compensation, and growers in these regions must be concerned with any management practice or pest that results in crop delay. This study was basically a repeat of our year 2000 study and had the following objectives: 1) to compare cotton crop response to square loss caused by plant bugs with that caused by removing squares by hand, and 2) to assess cotton plant responses with standardized procedures that synthesize information involving boll loading, metabolic stress, and crop carrying capacity. We confirmed that the cotton crop responds differently to injury from tarnished plant bug feeding than to injury caused by hand-removing squares from. Results provide convincing evidence that researchers should use live insects rather than hand-removal of squares in their research protocol, if their goal is to accurately study plant response to injury by tarnished plant bugs.
Technical Abstract: Effects of early square removal on cotton (Gossypium hirsutum L.) development were evaluated in normal and extremely late plantings in Northeast Arkansas in 2001. Squares were removed either by feeding by tarnished plant bug (TPB; Lygus lineolaris Palisot de Beauvois) or manually by crushing. Injury treatments were initiated when first squares were visible, 41 days after planting (DAP), and continued at 48 and 55 DAP. All visible squares were crushed on each treatment date. For TPB treatments, 3 nymphs, 2nd to 3rd instar, were released per plant. Plant response was monitored using COTMAN in-season with final plant mapping done using COTMAP. Square shed of 1st position squares at 59 DAP ranged from 8% in protected cotton to 39 and 45% following Bug or Crush treatments, respectively. Physiological cutout (nodes above white flower (NAWF)= 5) was delayed by 8 days for plants with insect induced injury compared to plants protected by insecticide. Differences in final plant structure and crop compensation following plant bug injury compared to manual square removal were observed. Mean maturity date for plants injured by plant bugs was 6 days later than either manually injured plants or protected plants. Plots were picked 5 times, and results indicated significant differences between treatments in the first 4 harvests. By the final harvest on 19 Oct, there were no statistical differences in final cumulative yield. Data from the 2001 study were similar to observations made in 2000 and indicated that crop response to injury from tarnished plant bug feeding was measurably different from response to manually induced injury. Results provide evidence that researchers should use insects in their research protocol rather than manually induced injury, if their goal is to accurately study plant response to feeding by tarnished plant bug.