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Fungus Puccinia recondita: Link to photo information
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Hairy Experience Can Frustrate Leaf-Infecting Fungi

By Dawn Lyons Johnson
July 25, 1997

“Hairy” plant leaves could provide an environmentally friendly defense against crop- damaging fungi like Puccinia recondita, the culprit behind leaf rust that costs wheat and rye growers millions of dollars in crop losses each year.

By examining leaf surfaces under a scanning electron microscope, scientists with USDA’s Agricultural Research Service were able to see how hair-like structures on leaf surfaces entangle and trap fungal spores that land and try to take hold.

When a spore settles on the leaf surface, the scientists say, it germinates and sends out a root-like structure called an “infection tube” in search of stomates--small pores on the surface of the plant that allow the leaf to take in carbon dioxide from the atmosphere. Carbon dioxide helps fuel the plant’s growth.

But when fungal spores land on a plant surface that has a high number of leaf hairs, the spores can become enmeshed and die before the infection tube successfully locates a stomate.

Previous research showed disease infestation was reduced up to 27 percent in plants with more leaf hairs. Scientists hope wheat and rye breeders will use the information to bred hybrids with this characteristic, which could help growers reduce their use of fungicides and other disease-killing pesticides.

A longer feature with photograph can be seen on the World Wide Web at:


Scientific contact: Dave L. Long, ARS Cereal Rust Laboratory, St. Paul, Minn., phone (612) 625-1284, fax (612) 649-5054,