Studies on the “Lake Venice disease” of Eurasian milfoil in the Chesapeake Bay

Abstract

Eurasian water milfoil (Myriophyllum spicatum L.) which showed symptoms of “Lake Venice disease” was studied under laboratory conditions. In tanks containing distilled water, diseased plants produced only disease-free tissue. We were unable to produce symptoms of “Lake Venice disease” either by direct inoculation of healthy plants with extracts from diseased plants or by growing diseased and healthy plants in the same tank grown with Gro-Lux illumination. However, plants grown under low light intensity (indirect sunlight) and inoculated with extracts from diseased tissue produced symptoms resembling those of “Lake Venice disease”. “Lake Venice disease” occurs on milfoil plants growing under stress conditions such as low light intensity, which increases the susceptibility of the plant to attack by microorganisms.