Net blotch on winter barley
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Symptoms of net blotch (Pyrenophora teres)
appeared in a campus research plot and a grower’s field of winter
barley in Ingham County this week. The foliage had numerous small dark
green to light brown spots, and some larger parallel brown stripes and
blotches with yellow halos. (see photo) Wheat is not affected by net
blotch.
Although there is relatively little barley grown in Michigan, this
fungal disease is common wherever barley is grown. As symptoms advance,
stripes get larger and can expend the length of the leaf. Lesions can
cover and kill entire leaves if disease is severe. Disease may also
infect the barley kernels. The fungus spreads mainly from barley residue
and volunteer barley plants, but can be transmitted on seed. The
disease is favored by windy conditions, high humidity and temperatures
in the 60°F to 80°F range. If infected seeds are planted, emerging
shoots can be infected after the seeds germinate. Prevention is the best
way to deal with net blotch, including crop rotation, removal of crop
residue and volunteer plants using resistant varieties and starting with
clean seed. If infection has already taken place, there are several
fungicides labeled for net blotch.