Smither-Kopperl, M.L., R. Charudattan, and R.D. Berger, 1999. Plectosporium Tabacinum, a Pathogen of the Invasive Aquatic Weed Hydrilla verticillata in Florida, University of Florida.

Reprinted from Plant Disease (1999) 83(1): 24-28

Abstract
Plectosporium tabacinum, the anamorph of Plectosphaerella cucumerina, was isolated in 1996 from Hydrilla verticillata (hydrilla), an invasive aquatic weed in Florida. P. tabacinum, applied as a suspension of conidia, was pathogenic to hydrilla shoots maintained in aqueous solutions in test tubes. Koch's postulates were fulfilled in several repeated experiments. Infected shoots became slightly chlorotic within 24 h after inoculation. Infected leaves remained intact and were supported by water pressure but collapsed upon removal from water. Histological studies of leaves stained with malachite green and acid fuchsin revealed fungal hyphae within plant cells. The disease developed over a range of temperatures from 15 to 30 degrees C. At 25 ° C, symptoms were most severe in 5% Hoagland's solution, followed by river water, deionized water, 0.5% Hoagland's, tap water, and spring water. Disease severity increased as inoculum concentration wits increased from 10⁵ to 10⁷ conidia ml^-1. This is the first report of P. tabacinum as a pathogen of hydrilla, a fully submerged aquatic plant species.

Entire Paper
Contact: M.L. Smither-Kopperl, University of Florida, Department of Plant Pathology, Gainesville, FL 32611 
Keywords: Hydrilla, Basic_biology, Biological_control 
Product Type: Research, Control
User Type: Resource Management