The widespread, rapid evolution of herbicide-resistant weeds is a serious and escalating agronomic problem worldwide. During China’s economic boom, the country became one of the most important herbicide producers and consumers in the world, and herbicide resistance has dramatically increased in the past decade and has become a serious threat to agriculture. Here, following an evidence-based PRISMA (preferred reporting items for systematic reviews and meta-analyses) approach, we carried out a systematic review to quantitatively assess herbicide resistance in China. Multiple weed species, including 26, 18, 11, 9, 5, 5, 4, and 3 species in rice (Oryza sativa L.), wheat (Triticum aestivum L.), soybean [Glycine max (L.) Merr.], corn (Zea mays L.), canola (Brassica napus L.), cotton (Gossypium hirsutum L.)., orchards, and peanut (Arachis hypogaea L.) fields, respectively, have developed herbicide resistance. Acetolactate synthase inhibitors, acetyl-CoA carboxylase inhibitors, and synthetic auxin herbicides are the most resistance-prone herbicides and are the most frequently used mechanisms of action, followed by 5-enolpyruvylshikimate-3-phosphate synthase inhibitors and protoporphyrinogen oxidase inhibitors. The lack of alternative herbicides to manage weeds that exhibit cross-resistance or multiple resistance (or both) is an emerging issue and poses one of the greatest threats challenging the crop production and food safety both in China and globally.

Since its initial introduction in the late 1950s, chemical control has dominated weed management practices in China. Not surprisingly, the development of herbicide resistance has become the biggest threat to long-term, sustainable weed management in China. Given that China has followed the same laissez-faire approach towards resistance management that has been practiced in developed countries such as the United State of America, herbicide resistance has rapidly evolved and steadily increased over the years. Previously, we carried out a systematic review to quantitatively assess herbicide resistance issues in China. In this review, our main objective is to focus on mechanistic studies and management practices to document the 1) history of herbicide application in China; 2) resistance mechanisms governing the eight most resistance-prone herbicide groups, including acetolactate synthase inhibitors, acetylCoA carboxylase inhibitors, synthetic auxin herbicides, 5-enolpyruvylshikimate-3-phosphate synthase inhibitors, protoporphyrinogen oxidase inhibitors, photosystem I electron diverters, photosystem II inhibitors, and long-chain fatty-acid inhibitors; and 3) herbicide resistance management strategies commonly used in China, including chemical, cultural, biological, physical, and integrated approaches. At the end, perspectives and future research are discussed to address the pressing need for the development of integrated herbicide resistance management in China.

Large crabgrass, Digitaria sanguinalis (L.) Scop., is a devastating weed species in the cotton (Gossypium spp.) fields in China. It has developed resistance to haloxyfop-P-methyl, an aryloxyphenoxypropionate herbicide known for its ability to inhibit lipid synthesis and induce oxidative stress in weeds, due to years of continuous and intensive use. Here, we present the results from a nation-wide, long-term resistance monitoring effort. To understand the scale and level of haloxyfop-P-methyl resistance, a total of 65 D. sanguinalis populations from eight cotton production provinces, including Hunan, Jiangxi, Xinjiang, Henan, Hubei, Hebei, Shanxi, and Anhui, were collected from 2014–2017. Based on results from dose response to haloxyfop-P-methyl, we observed a gradient of sensitivity to haloxyfop-P-methyl among 65 field populations, ranging from sensitive (8), to low-level resistance (40; 2 ≤ RI ≤ 10) to moderate-level resistance (17; 10 < RI < 20). Although no high-level resistance (RI > 20) was found among the 65 populations, populations from Hunan and Hebei exhibited a rapid spread of field-evolved resistance. After challenged with haloxyfop-P-methyl (48.600 g a.i./ha at the 4–5-leaf stage), resistant and susceptible D. sanguinalis responded differently in the activity of an array of resistance-related enzymes, including acetyl-CoA carboxylase (ACCase), glutathione S-transferase (GSTs), nicotinamide-adenine dinucleotide phosphate (NADPH) and carboxylesterase (CarE), suggesting the potential involvement of NADPH, CarE and GSTs in D. sanguinalis to haloxyfop-P-methyl resistance.