Blinka, E., J. Bacheler, P. Roberts, J. Greene, M. Toews, D. Mott, Evaluation of the relationship between stink bug pressure vs. yield under a regressive spray treatment. Blinka, E., J. Bacheler, P. Roberts, J. Greene, M. Toews, D. Mott, D. Robinson, J. Van Duyn NCSU Clemson UGA

INTRODUCTION Stink bugs can reduce yields and cotton quality (Barbour, et al. 1990, Bundy, et al. 1999, Greene and Herzog 2001, Willrich et al. 2003, Emfinger et al. 2004). TAMU Extension

INTRODUCTION Stink bug pest status continues to increase in cotton, infesting 6.516 million acres and destroying 151,341 bales across the U.S. in 2006 (Williams 2007). North Carolina: 51,607 bales lost. South Carolina: 20,488 bales lost. Georgia: 25,000 bales lost.

INTRODUCTION Bacheler et al. (2007) suggested that 3.5+ week old bolls or 1.25 inch diameter bolls are safe from stink bug feeding damage. Bacheler et al. (2007) suggest that higher stink bug thresholds in cotton may be justified during both early and late periods of bloom.

OBJECTIVE Evaluate the relationship between stink bug pressure vs. yield under a regressive spray treatment.

MATERIALS AND METHODS Series of seven regressive spray treatment tests: two in NC in 2006 & 2007, two in GA in 2007, and one in SC in 2007. X X NC X X SC X = 2007 X = 2006 GA X X X

MATERIALS AND METHODS 3 5 6 7 2 4 1 Figure 1. Number of applications per plot. All plots were treated first week of bloom except Untreated Check plots (UTC). Each week, another plot was removed from the spray schedule.

MATERIALS AND METHODS Just prior to boll opening, 25 randomly selected bolls per plot (100/treatment) were assessed internally and deemed damaged if any internal warts, stained lint, or a combination of the two were found. Middle two rows from all treatments at all locations were mechanically harvested and weighed to determine yields, except NC, Perquimans Co. in 2006 was hand harvested.

MATERIALS AND METHODS Yield data were subjected to ANOVA and means were separated by LSD (p = 0.05)

RESULTS Location and Year % Damaged Bolls NC, Edgecombe Co. 2006 23% Table 1. Percent Year End Boll Damage. Location and Year % Damaged Bolls NC, Edgecombe Co. 2006 23% NC, Perquimans Co. 2007 48% NC, Wayne Co. 2007 32%

RESULTS a a a a a a a a

Differences in Yield Based on Weekly Sprays (lbs. lint/acre) RESULTS (Yield Difference: Treated vs UT = -152.46 lbs. lint/acre) 261.36 185.10 43.56 163.35 Differences in Yield Based on Weekly Sprays (lbs. lint/acre) -32.67 -533.61 6-5 5-4 4-3 3-2 2-1 1-0 Week of Bloom

Differences in Yield Based on Weekly Sprays (lbs. lint/acre) RESULTS (Yield Difference: Treated vs UT = 2.9 lbs. lint/acre) 44.7 36.6 29.9 Differences in Yield Based on Weekly Sprays (lbs. lint/acre) -10.8 -3.7 -49.1 -50.5 5-4 7-6 6-5 4-3 3-2 2-1 1-0 Week of Bloom

Differences in Yield Based on Weekly Sprays (lbs. lint/acre) RESULTS (Yield Difference: Treated vs UT = 30.2 lbs. lint/acre) 113.03 72.60 9.88 Differences in Yield Based on Weekly Sprays (lbs. lint/acre) -31.94 -40.65 -112.68 -121.74 5-4 7-6 6-5 4-3 3-2 2-1 1-0 Week of Bloom

Differences in Yield Based on Weekly Sprays (lbs. lint/acre) RESULTS (Yield Difference: Treated vs UT = 222.2 lbs. lint/acre) 48.0 26.8 Differences in Yield Based on Weekly Sprays (lbs. lint/acre) -31.2 -44.3 -61.0 -70.4 -90.1 5-4 7-6 6-5 4-3 3-2 2-1 1-0 Week of Bloom

Differences in Yield Based on Weekly Sprays (lbs. lint/acre) RESULTS (Yield Difference: Treated vs UT = -10.35 lbs. lint/acre) 129.45 129.03 103.13 23.33 Differences in Yield Based on Weekly Sprays (lbs. lint/acre) -74.93 -108.68 -190.03 5-4 7-6 6-5 4-3 3-2 2-1 1-0 Week of Bloom

Differences in Yield Based on Weekly Sprays (lbs. lint/acre) RESULTS (Yield Difference: Treated vs UT = 248.3 lbs. lint/acre) 49.37 Differences in Yield Based on Weekly Sprays (lbs. lint/acre) -29.04 -27.59 -39.21 -55.17 -68.25 -78.41 5-4 7-6 6-5 4-3 3-2 2-1 1-0 Week of Bloom

Differences in Yield Based on Weekly Sprays (lbs. lint/acre) RESULTS (Yield Difference: Treated vs UT = -84.37 lbs. lint/acre) 145.31 93.77 Differences in Yield Based on Weekly Sprays (lbs. lint/acre) 47.92 -4.13 -43.79 -67.86 -86.89 5-4 7-6 6-5 4-3 3-2 2-1 1-0 Week of Bloom

RESULTS Yield change from spray at designated weeks of bloom, NC & GA, 2004 - 2006 under a progressive spray environment (n = 14 tests) Bacheler et al. 2007. 62.6 Lb. Lint/Acre 17.1 15.3 -7.0 -9.2 -21.9 1-2 2-3 3-4 4-5 5-6 6-7 Week of Bloom

RESULTS Yield change from spray at designated weeks of bloom, NC, SC, & GA, 2004 - 2006 under a regressive spray environment (n = 7 tests). 31.48 19.62 17.83 -9.41 -4.38 -18.79 Lb. Lint/Acre -86.56 7-6 6-5 5-4 4-3 3-2 2-1 1-0 Week of Bloom

RESULTS (Yield difference: treated vs. UT) (479) (762) (8) (-15) (106) Relationship between stink bug damage to quarter-sized bolls and yield loss, 2005 – 2006 (Bacheler et al. 2007). (Yield difference: treated vs. UT) (479) (762) (8) (-15) (106) Wayne, NC 2004 GA 2005 Union, NC 2005 Scot., NC 2006 SC 2006

CONCLUSIONS 2006 appeared to be a light stink bug year with 2007 being even lighter. Yield data showed a numerical trend towards higher yields under 4 or more spray treatments. High variation occurred between cotton lint gained or loss based on weekly spray treatments at all locations and years.

CONCLUSIONS Reverse spray treatment data did not follow trends noted under a progressive spray treatment. Light stink bug activity may explain some of the variation. More Questions than Answers!

CONCLUSIONS Is it possible that initial spray treatments reduced stink bug levels that were not able to rebound for remainder of experiment? We need to gain more information concerning the impact of low stink bug levels on cotton.

“Identifying Practical Knowledge and Solutions for Managing The Sucking-Bug Complex In Cotton: Research In The Southeast Region” Southeast State Support Committees