|BREWER, MIKE - Texas Agrilife
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2012
Publication Date: N/A
Technical Abstract: Cotton along the Gulf Coast of south Texas has experienced loss from cotton boll rot especially during the last 10 to 15 years, and stink bugs and plant bugs (Hemiptera: Pentatomidae and Miridae) that feed on cotton bolls have been suspected in introducing the disease. A replicated grower field survey was done to capture a representation of these sucking bug species and subsequent boll injury, including cotton boll rot, in 2010 and 2011. This survey was paired with a controlled field cage experiment that isolated feeding by verde plant bug, Creontiades signatus Distant (Hemiptera: Miridae). Verde plant bug was the dominant boll-feeding sucking bug species (-99% of insects collected) during peak to late bloom in cotton fields within 8 km of coastal waters (average of 0.42 bugs per plant), while it was not detected in inland fields. Cotton boll rot was found on up to 25% of the open bolls inspected, the disease was concentrated in coastal fields where verde plant bug was found. Isolating verde plant bug feeding further implicated it in introducing cotton boll rot. Verde plant bug-infested plants had significantly higher incidence of insect-punctured bolls and locules (15-35% in infested plants) and disease symptom incidence (5-27% in infested plants) than uninfested plants. All bolls with symptoms of disease tested positive for bacteria. Based on field data from 14 fields, stepwise regression using 4 independent variables (verde plant bug per plant [using a beat bucket or sweep net], proportion of green bolls with signs of external feeding, proportion of green bolls with signs of internal feeding, and proportion of green bolls with signs of boll rot) identified a one independent variable model as the best indicator of at-harvest boll damage. Verde plant bug per plant using a beat bucket was the selected model. Input of other variables did not increase the informative value of the regression using beat bucket sampling for verde plant bugs as an indicator of at-harvest damage. Because verde plant bug presence is an early step in the sequence of events leading to boll damage, opening bolls to verify internal feeding may be useful to supplement the beat bucket sampling method. From a pest and disease monitoring viewpoint, an in-season insect monitoring program is justified and needed most critically for fields close to coastal waters.