Question

kudzu scientists try to tame a self-replicating monster

1. since the 1970s, an alabaman named jim miller has operated what could be described as the 911 line for kudzu victims. “within my first six months of getting hired to do invasive plant management for the u.s. forest service, i got letters from two ladies whose deceased husbands had planted kudzu, and it was growing all around their houses,” recalls miller, a forest service ecologist. “one of the women said, ‘i have these nightmares of these vines coming in at night and getting me.’” the tenor of the outreach—“help me, help me!”—has persisted for more than 30 years, adds miller. these days, many of the cries for help come by e-mail.
2. miller has spent the bulk of his career looking for a way to smother kudzu. he tried hand-digging, mowing, burning, grazing livestock—all to no avail. he traveled frequently to exchange war stories with other ecologists and agriculturalists. “i’d get up in a county meeting with a slide show and explain my work and these old guys would say, ‘we know how to control kudzu!’ either it had

which factor most contributed to kudzu becoming an invasive plant in the u.s.?
farmers did not have chemicals to control it.
warm southern climate allowed it to flourish.
ineffective methods allowed it to flourish.
native predators did not exist to control it.

Explanation:

Invasive species often thrive when there are no natural predators to keep their population in check. This is a key concept in ecology. Kudzu being invasive in the U.S. likely relates to the absence of native predators that would control its growth.

Answer:

Native predators did not exist to control it.