An unusual, white-flowered kenaf plant appears highly resistant to powdery mildew, a costly disease that can attack kenaf leaves and seed pods in fall. Caused by a microbe known as Leveillula taurica, powdery mildew can lower the quality and quantity of commercial kenaf seed harvests. A fast-growing, bamboo-like relative of okra and cotton, kenaf makes a bright, high-quality paper that resists yellowing. Kenaf can also be processed into acoustic tile, cat litter, bedding for horses and other animals, composite board for construction, mats for erosion control and grass seeding, and pads for cleaning up chemical or oil spills. ARS scientists first noticed the unique kenaf in a plant nursery in Mexico, then tested it in the United States in field and greenhouse experiments. Unlike commercial kenaf varieties, which produce yellow flowers, the experimental line—designated PVWF-90—bears smaller, white blooms. Because the white-flower characteristic is inherited and distinctive, this feature may prove to be an easily detected genetic marker of powdery mildew resistance. That could simplify breeding of new commercial lines of kenaf that boast this valuable trait. Besides providing the raw material for a variety of products, kenaf plants might also prove useful in cleaning up soil or water—a process known as phytoremediation. To determine whether kenaf could, for example, remove excess selenium from soils irrigated with selenium-rich water, ARS researchers and their colleagues in USDA’s Natural Resources Conservation Service conducted a phytoremediation experiment with 120,000 kenaf plants. They grew the plants at a 1-acre site in central California. The hardy, deep-rooting kenaf plants shot up nearly 15 feet in only 6 months and removed about 25 percent of the soluble selenium that had accumulated in the first 3 feet of soil.

Water Management Research Unit, Fresno, CA
Gary S. Bañuelos, (559) 453-3115, banuelos@asrr.arsusda.gov