Pesticide and Environmental Update
Herbs May
Fight Spud Blight
Fine chefs may wince, but scientists with the Agricultural Research
Service (ARS) are reaching into the cupboard and finding unconventional
uses for such culinary classics as oregano and thyme, testing the herbs’
potency in a messy battle out on the farm.
ARS plant pathologist Modesto Olanya and colleagues are investigating
plant essential oils—including oregano, thyme and lavender—and other
biologically based approaches to control one of the most devastating
potato diseases worldwide: late blight. Potato plants infected with the
fungal spoiler, called Phytophthora infestans, may be rapidly defoliated
and destroyed.
The fungal disease, blamed for the Irish potato famine of the 1840s, is
a formidable disease to fend off. It quickly gains resistance to widely
used systemic fungicides, requiring researchers to constantly search for
new ways to protect America’s favorite vegetable from the fungal threat.
Olanya, who works at ARS’ New England Plant, Soil and Water Research
Laboratory in Orono, Me., has found that among the essential oils, oregano
is showing the greatest promise as a late blight suppressor. In laboratory
tests, the Maine researchers found that oregano and other essential oils
greatly inhibited the growth of P. infestans fungi. However, oregano was
less effective in suppressing late blight in growth chamber studies than
in the laboratory.
If future studies continue to show promise, natural remedies such as
essential oils could someday reduce a portion of the many fungicides used
to prevent late blight from taking root in U.S. potato fields each year.
To increase their efficacy, Olanya is looking at pairing essential oils
with other natural products, such as beneficial microorganisms.
The essential oils do have some limitations to overcome. According to
Olanya, oregano is fairly volatile, meaning some of its fungi-fighting
essence could evaporate from plant surfaces after it’s been applied.
Conversely, the oils can burn plant leaves if applied too generously.
|
