Researchers with the University of Arizona continue to study lettuce and spinach varieties for better control of downy mildew, a naturally occurring pathogen that renders plants unmarketable.

Bindu Poudel, an Extension plant pathologist at UA's Yuma research farm continues to test lettuce varieties and a variety of fungicides to help growers tackle the problem.

Three lettuce varieties – Magosa, Bobcat and a numbered variety -- are being studied, along with 20 different fungicides. Aside from mildew damage, the plot at the Yuma Ag Center showed signs of wind and insect damage during a recent field day offered to allow growers to come and go.

The two varieties are said to be good candidates for a downy mildew trial, according to one Yuma-area grower. Neither are widely used for commercial production anymore because of their tendency to be affected by the pathogen.