Herbicides and plant hormesis

Authors: BELZ, REGINA - University Of Hohenheim; Duke, Stephen

Submitted to: Pest Management Science
Publication Type: Review Article
Publication Acceptance Date: 1/13/2014
Publication Date: 1/20/2014
Citation: Belz, R.G., Duke, S.O. 2014. Herbicides and plant hormesis. Pest Management Science. 70:698-707.

Interpretive Summary: Herbicide hormesis is commonly observed at sub-toxic doses of herbicides and other phytotoxins. The occurrence and magnitude of this phenomenon is influenced by plant growth stage and physiological status, environmental factors, the endpoint measured, and the timing between treatment and endpoint measurement. The mechanism in some cases of herbicide hormesis appears to be related to the target site of the herbicide, whereas, in other examples hormesis may be by overcompensation to moderate stress induced by the herbicides or a response to disturbed homeostasis. Theoretically, herbicide hormesis could be used in crop production, but this has been practical only in the case of the use of herbicides as sugarcane “ripeners” to enhance sucrose accumulation. The many factors that can influence the occurrence and magnitude of hormetic increases in yield for most crops make it too unpredictable and risky as a production practice with the currently available knowledge. Herbicide hormesis can cause undesired effects in situations in which weeds are unintentionally exposed to hormetic doses (e.g., in adjacent fields, when shielded by crop vegetation). Some weeds that evolved herbicide resistance may have hormetic responses to recommended herbicide application rates. Little is known about such effects under field conditions. A more complete understanding of herbicide hormesis is needed to exploit its potential benefits and to minimize its potential harmful effects in crop production.

Technical Abstract: Herbicide hormesis is commonly observed at sub-toxic doses of herbicides and other phytotoxins. The occurrence and magnitude of this phenomenon is influenced by plant growth stage and physiological status, environmental factors, the endpoint measured, and the timing between treatment and endpoint measurement. The mechanism in some cases of herbicide hormesis appears to be related to the target site of the herbicide, whereas, in other examples hormesis may be by overcompensation to moderate stress induced by the herbicides or a response to disturbed homeostasis. Theoretically, herbicide hormesis could be used in crop production, but this has been practical only in the case of the use of herbicides as sugarcane “ripeners” to enhance sucrose accumulation. The many factors that can influence the occurrence and magnitude of hormetic increases in yield for most crops make it too unpredictable and risky as a production practice with the currently available knowledge. Herbicide hormesis can cause undesired effects in situations in which weeds are unintentionally exposed to hormetic doses (e.g., in adjacent fields, when shielded by crop vegetation). Some weeds that evolved herbicide resistance may have hormetic responses to recommended herbicide application rates. Little is known about such effects under field conditions. A more complete understanding of herbicide hormesis is needed to exploit its potential benefits and to minimize its potential harmful effects in crop production.