Researchers crabgrass hydroponically, so they could easily capture any chemicals released by the plant's roots. Then they dripped that hydroponic solution into pots of wheat, corn and soybean seedlings. Two weeks later, they dried and weighed the seedlings. And sure enough, the crabgrass solution had significantly stunted the seedlings’ growth, compared to control plants. And since corn is in the same family as lawn grasses, the crabgrass toxic effect may also spell bad news for your beautiful Kentucky bluegrass.
The researchers still aren't exactly sure how crabgrass' chemical weapons work. But the weed can wipe out beneficial bacteria and fungi in the soil, too. So it’s possible that crabgrass poisons its neighbors directly, by releasing toxins, and indirectly, by creating inhospitable soil. Either way, it's bound to make lawn owners crabby.
—Christopher Intagliata
