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Title: Differences in Clomazone Tolerance among Sweetpotato Varieties

item Harrison Jr, Howard
item Jackson, D

Submitted to: Weed Science Society of America Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 10/5/2008
Publication Date: 7/9/2009
Citation: Harrison Jr, H.F., Jackson, D.M. 2009. Differences in Clomazone Tolerance among Sweetpotato Varieties. Weed Science Society of America Meeting Proceedings and Weed Science Society of America. Abstract #48.

Interpretive Summary: N/A

Technical Abstract: Differences in clomazone tolerance between sweetpotato clones were first observed following use of the herbicide for weed control in fields containing the sweetpotato breeding project at the US Vegetable Laboratory. Susceptible clones exhibited severe foliar bleaching and reduced growth; whereas, the most tolerant lines were not injured. Twelve clones chosen based on these observations were included in a greenhouse experiment to quantify differences in clomazone tolerance. The most tolerant clone, Beauregard exhibited lower injury rating and shoot weight reduction at 8.0 mg ai clomazone/kg potting medium than the most susceptible clone, 04-N01, exhibited at 1.0 mg/kg. Based on response curves generated from regression analyses, the clomazone concentration that caused moderate injury or growth reduction in Beauregard clones was approximately 8 to 10 times greater than the concentration that caused a similar response in 04-N01. Fifty two commercial cultivars and advanced experimental lines were evaluated for clomazone tolerance in the greenhouse, and several susceptible lines were identified. Many of the sweetpotato clones demonstrating high or intermediate susceptibility to clomazone were developed by the sweetpotato breeding project at the U.S. Vegetable Laboratory. These clones were developed over many years and share a common ancestry, which suggests that clomazone susceptibility was passed genetically from one generation to the next. These observations indicate that some sweetpotato genotypes are highly susceptible to clomazone. Since the herbicide is an important component in sweetpotato weed management, developing cultivars that are susceptible should be avoided. The relatively large differences in clomazone tolerance observed in sweetpotato indicate that there is potential to breed cultivars with increased tolerance. Sweetpotato clones with increased tolerance would improve crop safety and may allow use of higher clomazone rates which control more weed species than are controlled with lower rates.