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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #246777
Title: Interactive Effects of Soil ph, Halosulfuron Rate, and Application Method on Carryover to Turnip Green and Cabbage.

Author
item Johnson, Wiley - Carroll
item GREY, T.L. - University Of Georgia
item KISSEL, DAVID - University Of Georgia

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2009
Publication Date: 2/17/2010
Citation: Johnson, W.C., Grey, T.L., Kissel, D. 2010. Interactive effects of soil ph, halosulfuron rate, and application method on carryover to turnip green and cabbage. Weed Technology. 24:160-164.

Interpretive Summary: Halosulfuron is commonly used in transplanted cucurbit crops to control perennial nutsedges. Crucifers are often planted in the autumn following cucurbit crop harvest. There is concern that soil pH outside acceptable levels may increase chances of halosulfuron carryover to autumn-planted crucifers. Field studies were conducted to evaluate the tolerance of autumn-planted cabbage and turnip green to halosulfuron applied the previous spring to cantaloupe. Main plots were three levels of soil pH; maintained at a natural pH level, pH raised with Ca (OH)2, and pH lowered with Al2(SO4)3. Sub-plots were two methods of halosulfuron application and three halosulfuron rates. Methods of application were pre-plant incorporated or postemergence after transplanting. Halosulfuron rates were 35 and 70 g ai/ha, along with a nontreated control. Halosulfuron at 35 g/ha is within the registered range of rates, while 70 g/ha represents conditions of excessive rates due to misapplication. Cantaloupe were transplanted and evaluated for crop tolerance and yield. After cantaloupe harvest, direct-seeded turnip green and transplanted cabbage were established in September of each year. Data indicated nonsignificant main effects of soil pH and halosulfuron application method on cantaloupe yield. However, in 2007 cantaloupe yields were significantly reduced by halosulfuron. After six months, there was no evidence of injury from halosulfuron carryover in 2006 to direct-seeded turnip green and both years to transplanted cabbage. Injury to direct-seeded turnip green ranged from 9 to 16% for halosulfuron at 35 and 70 g/ha, respectively in 2007, but all injury was transient and turnip green yield was not affected. These results show that soil pH does not affect halosulfuron carryover in these cropping systems and suggest that there is minimal risk from halosulfuron carryover to autumn-planted cucurbits when applied at registered rates.

Technical Abstract: Field studies were conducted in 2006 and 2007 to evaluate the tolerance of autumn-planted cabbage and turnip green to halosulfuron applied the previous spring to cantaloupe. Main plots were three levels of soil pH; maintained at a natural pH level, pH raised with Ca(OH)2, and pH lowered with Al2(SO4)3. Sub-plots were a factorial arrangement of two methods of halosulfuron application and three halosulfuron rates. Methods of application were pre-plant incorporated (PPI) or postemergence after transplanting to the edges of mulch-covered seedbed (POST). Halosulfuron rates were 35 and 70 g ai/ha, along with a nontreated control. Cantaloupe were transplanted and evaluated for crop tolerance and yield. After cantaloupe harvest, direct-seeded turnip green and transplanted cabbage were established in September of each year and evaluated for crop tolerance and yield. Data indicated nonsignificant main effects of soil pH and halosulfuron application method on cantaloupe yield. However, in 2007 cantaloupe yields were significantly reduced by 16 and 20% for halosulfuron applied at 35 and 70 g/ha, respectively. Interactions were non-significant for all parameters between application method and rate, soil pH and rate, and soil pH and application method, along with the three-way interaction among soil pH, application method, and rate. After six months, there was no evidence of injury from halosulfuron carryover in 2006 to direct-seeded turnip green and both years to transplanted cabbage. Injury to direct-seeded turnip green ranged from 9 to 16% for halosulfuron at 35 and 70 g/ha, respectively in 2007, but all injury was transient and turnip green yield was not affected.