Some farming methods used to fight the menace such as growing herbicide-tolerant rice varieties have failed to stem the weedy rice invasion. While the origins of weedy rice are unclear, several of its varieties began to emerge in Asia about two decades ago.

Asia's bountiful rice fields have fed the world for centuries, but the industry now faces a threat from a weedy “cousin” of the staple that has proliferated due in part to poor farming practices.

Mealy in texture with dark pigmentation and unfit for consumption, weedy rice can grow rapidly and taller than the regular crop varieties, depriving the latter of soil nutrients and sunlight.

As a result of the invasive weedy rice, harvest quality, yields and in turn market value of regular rice have declined significantly in recent years.

“They have become feral through a sort of accidental selection. They will eventually stick out over a crop field, but the problem is that by the time they are visible, there can often be quite an infestation,” Kenneth Olsen, Professor of Biology at Washington University, told This Week in Asia.

“A major weedy rice infestation can reduce crop harvests in a given field by over 80 per cent,” he said.

Source - www.scmp.com