A new study in China has identified what makes crabgrass tough. According to the study, crabgrass, a persistent and unwanted weed, produces a powerful herbicide that kills nearby plants. This is contrary to the popular belief that crabgrass dominates in lawns, gardens and farmers' fields by simply overcrowding other plants. This discovery could lead to the development of new herbicide.

Scientists have long suspected that crabgrass thrived by allelopathy which occurs when one plant restricts the growth of another by releasing toxins. The team from China Agricultural University set out to determine if crabgrass has this ability. They isolated three chemicals from crabgrass that affect the microbial communities in nearby soil and inhibit the growth of staple crops wheat, corn and soybeans. They found that the chemical-specific changes in soil microbial community generated a negative feedback on crop growth, noting that the chemicals also would have a direct toxic effect on other plants.

Results of this study was published in the Journal of Agricultural and Food Chemistry where the full paper is available at http://pubs.acs.org/doi/abs/10.1021/jf401605g