High [CO2] and Temperature Increase Resistance to Cyhalofop-Butyl in Multiple-Resistant Echinochloa colona

Abstract

Changes in the environment, specifically rising temperature and increasing atmospheric carbon dioxide concentration [CO 2 ], can alter the growth and physiology of weedy plants. These changes could alter herbicide efficacy, crop-weed interaction, and weed management. The objectives of this research were to quantify the effects of increased atmospheric [CO 2 ] and temperature on absorption, translocation and efficacy of cyhalofop-butyl on multiple-resistant (MR) and susceptible (S) Echinochloa colona genotypes. E. colona , or junglerice, is a troublesome weed in rice and in agronomic and horticultural crops worldwide. Cyhalofop-butyl is a grass herbicide that selectively controls Echinochloa spp. in rice. Maximum 14 C-cyhalofop-butyl absorption occurred at 120 h after herbicide treatment (HAT) with >97% of cyhalofop-butyl retained in the treated leaf regardless of [CO 2 ], temperature, or genotype. Neither temperature nor [CO 2 ] affected herbicide absorption into the leaf. The translocation of herbicide was slightly reduced in the MR plants vs. S plants either under elevated [CO 2 ] or high temperature. Although plants grown under high [CO 2 ] or high temperature were taller than those in ambient conditions, neither high [CO 2 ] nor high temperature reduced the herbicide efficacy on susceptible plants. However, herbicide efficacy was reduced on MR plants grown under high [CO 2 ] or high temperature about 50% compared to MR plants at ambient conditions. High [CO 2 ] and high temperature increased the resistance level of MR E. colona to cyhalofop-butyl. To mitigate rapid resistance evolution under a changing climate, weed management practitioners must implement measures to reduce the herbicide selection pressure. These measures include reduction of weed population size through reduction of the soil seedbank, ensuring complete control of current infestations with multiple herbicide modes of action in mixture and in sequence, augmenting herbicides with mechanical control where possible, rotation with weed-competitive crops, use of weed-competitive cultivars, use of weed-suppressive cover crops, and other practices recommended for integrated weed management.

Recurrent Selection by Herbicide Sublethal Dose and Drought Stress Results in Rapid Reduction of Herbicide Sensitivity in Junglerice

“…Abiotic stresses such as CO 2 limitation , drought, and heat also impart selection pressure on plants in addition to herbicides and, therefore, can accelerate the evolution of herbicide-resistant plants. Previous related research and our current study support this premise [7,55,62]. Drought stress is a good example of an environmental stress that easily compromises herbicide performance.…”

“…Echinochloa colona (L.) Link, commonly known as junglerice, a self-pollinating species, is among the top five worst weeds in the world, being a persistent threat in 35 cropping systems in more than 60 countries [5][6][7][8]. To prevent yield losses, weed control has been almost exclusively done with herbicides [9][10][11].…”

Non-Target-Site Resistance to Herbicides: Recent Developments

“…Additionally, increased absorption of glyphosate in common ragweed, and increased absorption and translocation of glyphosate in giant ragweed, improved glyphosate efficacy at high temperature [134]. Apart from temperature, changes in CO 2 concentrations can affect herbicide translocation and sequestration in weeds [140,143]. In horseweed and lambsquarter, an increase in glyphosate translocation was found at elevated CO 2 levels and increased temperature, leading to a reduced glyphosate sensitivity [140].…”

“…In horseweed and lambsquarter, an increase in glyphosate translocation was found at elevated CO 2 levels and increased temperature, leading to a reduced glyphosate sensitivity [140]. Similarly, in Echinochloa colona , high CO 2 and increased temperature reduced the efficacy of cyhalofop-butyl by decreasing translocation [143]. Altering relative humidity (RH) can also affect herbicide translocation in pigweeds [144].…”

Response of imidazolinone-resistant and -susceptible weedy rice populations to imazethapyr and increased atmospheric CO2

“…Some researchers have explored the behavior of weedy rice in relation to climate change, specifically, increased atmospheric [CO2] (Ziska and McClung, 2008;Ziska et al, 2014). In a recent study, Refatti et al (2019) found that increasing atmospheric [CO2] and temperature may increase the speed of junglerice resistance evolution to herbicides. The combined effect of increased [CO2] and herbicide application on weeds is an important aspect to address in relation to crop production.…”