Potatoes infected
with late blight are shrunken on the outside, corky and rotted inside.
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Kitchen Meets Farm in Fight Against Late Blight
By Erin
Peabody March 13, 2006
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 oilsincluding
oregano, thyme and lavenderand 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 Americas 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 its been applied. Conversely,
the oils can burn plant leaves if applied too generously.
ARS is the chief scientific research agency of the
U.S. Department of Agriculture.