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Mechanical Methods Offer alternatives To Reducing Weed Seedbank Persistence

published: September 9th 2008
source: Weed Science

A new study published in Weed Science reports that weed seed destruction and predation are practical alternatives to the use of herbicides as a weed population management technique.

Because persistent weed seeds survive longer than their next vegetation period, unlike transient weed seeds, it is important to identify management approaches that address the problems associated with seed dormancy.

Scientists analyzed chemical and physical methods of defense in six weed species commonly found in grain crop production fields in the Midwest region of the United States. After measuring chemical concentrations of phenol and applying four types of physical damage to each species, the researchers discovered, contrary to their expectations and reports in other studies, that as seed persistence increased, chemical protection decreased.

In addition, it was found that just a small amount of damage applied to highly persistent weed seeds resulted in their destruction, because their chemical defenses were not strong enough to protect them from opportunistic fungi and bacteria.

It is therefore suggested that the use of harvest machinery be revisited. Harvest machinery that collects weed seeds need only damage the seeds slightly to be effective. This practical, mechanical approach was applied before herbicides became the preferred method of weed seed management some 50 years ago.

Another mechanical approach supported by this study is ensuring that predispersal predators, such as arthropods, are present to consume weed seeds or to pierce their coats, which would in turn encourage microbial predators to enter the seeds.

The mechanical methods of managing weed seedbanks through harvest machinery and predators are alternatives to herbicides and warrant the attention of the weed science community.

To read the entire study, visit http://www.allenpress.com/pdf/WEES-56-5-676.pdf