The study focused on three main problems: how willows are pollinated and how much seed they can make; how far willow pollen and seed can move across catchments; and, identifying trees and populations within catchments that are key seed ‘donators’.

“We discovered that this species of willow is pollinated by both insects and wind, and that the average willow tree can make 330,000 seeds in a season,” Ms Hopley said.

“That is about 25 million seeds generated each year by an average infestation along half a kilometre. Genetic paternity tests and spatial analysis were used to determine how pollen and seeds are dispersed across a typical catchment.

“The results show that over half the pollen and seed is moving more than 15 kilometres between rivers. This high rate of spread suggests that land managers have to act urgently on control efforts across the whole catchment if long-term eradication is going to be effective,” Ms Hopley said.

“We also found a small proportion of sites studied were producing a large proportion of the seed. In practical terms this means that clearing just 20 percent of sites could see a 50 percent reduction in seed production.”

The Director of the Centre for Australian National Biodiversity Research, CSIRO scientist Dr Andrew Young, said the research provides land managers with scientific information that make current willow removal efforts more efficient, saving money and time.

From http://www.bellingencourier.com.au, see original source.