Kill those weeds as soon as possible!

While that new species of weed on your land might seem innocuous, it could be only a matter of time before it spreads and causes bigger problems. So make sure to take care of the problem in a timely manner, says Bill Kerr.

- Bill Kerr

Invariably, when farmers come across a new species of weed on their lands, they ignore it. In most cases, however, this is the wrong thing to do. At first glance, a single plant or small cluster thereof might seem harmless, but, if left, it could be the vanguard of an invasion that cannot be stopped.

Not all species of weeds are equal. Some might just become part of the weed spectrum controlled by the usual herbicides, while others develop into a problem that requires special procedures to eliminate.

The threat may be different for different farmers, depending on their crops and specific herbicides. An example is the weed yellowtop (