California scientists will scrutinize an experimental potato hybrid that may contain genes for resistance to a new, more virulent strain of a disease called late blight. The new strain has recently shown up in the U.S.

Caused by the fungus Phytophthora infestans, late blight is the most destructive disease of potatoes worldwide.

The scientists are with USDA’s Agricultural Research Service in Albany, Calif., and Dry Creek Laboratories, Inc., of Modesto, Calif. The aim is to speed discovery of genes to protect crops from harmful fungi before and after harvest. The work is being done under a cooperative research and development agreement beween the company and ARS.

ARS scientist John P. Helgeson in Madison, Wis., developed the hybrid by fusing leaf cells from a late-blight-resistant species of wild potato with leaf cells from a cultivated potato variety.

If the California researchers find and clone a resistance gene, they intend to transfer it to commercial potato varieties.

Later experiments could reveal whether this potato gene can safeguard other crops from their worst fungal nightmares. Grapevines, for example, are continually threatened by the Uncinula necator fungus that causes powdery mildew. And walnut trees could benefit from a new source of resistance to Phytophthora fungi that cause root and crown rots.

Scientific contact: William R. Belknap, USDA-ARS Western Regional Research Center, Albany, Calif. 94710, phone (510) 559-6072