The proliferation of superweeds --weeds that have mutated to develop resistance to popular herbicides like Monsanto's Roundup formula --continues to rise. But the individual plants' overall size and strength is also increasing. According to a series of new studies published in the journal Weed Science, farmers are having more trouble than ever dealing with out-of-control superweeds in their fields, some of which grow up to three inches a day in size, and are so strong and thick that they are destroying farm equipment.The studies reveal that there are currently at least 21 different weed species known to be resistant to...