Credit: CC0 Public Domain

A new study in the journal Invasive Plant Science and Management shows that working smarter, not harder, can lead to better control of invasive weeds. And the first step is to clearly define your weed control objectives.

Do you want a quick, short-term reduction in a weed population or long-term control? Is your weed problem limited to a specific area, or are you also concerned about adjacent fields?

"Answering such questions can help you select the most appropriate management options and eliminate wasted effort," says Katriona Shea, a researcher at Pennsylvania State University.

To illustrate the importance of upfront decisions, researchers conducted a two-year study involving invasive thistle, a weed often found in pasturelands and rangelands. Mathematical models were used to determine which of 14 mowing strategies would best support each of three different management objectives: reducing the density of an existing thistle infestation, decreasing long-term population growth and limiting the 's spread.

Contrary to , researchers found that fewer, well-timed mowing events were more effective than mowing as often as possible—making it possible to produce a better outcome with less effort.

Intense mowing both before flowering and during the peak flowering period, for example, produced the best long-term control of invasive thistle and reduced both its abundance and its spatial spread. A single, intense mowing during the peak flowering period was the most effective approach for short-term management, which is good news for land managers with limited time and resources.

More information: Rui Zhang et al, Working smarter, not harder: objective-dependent management of an invasive thistle, Carduus nutans, Invasive Plant Science and Management (2019). DOI: 10.1017/inp.2019.18