|
Disease Note Induction of Silverleaf of Squash by Bemisia Whitefly from California Desert Whitefly Populations. S. Cohen, Visiting Scientist, Volcani Institute of Agricultural Research, Bet Dagan, Israel. J. E. Duffus, H. Y. Liu, and R. Perry. USDA-ARS, U.S. Agricultural Research Station, Salinas, CA 93905. Plant Dis. 75:862. Accepted for publication 18 March 1991. Copyright 1991 The American Phytopathological Society. DOI: 10.1094/PD-75-0862B. The silverleaf syndrome in squash, induced by the feeding of the
sweetpotato whitefly (Bemisia tabaci (Gennadius)), is widespread in
Florida (2). Populations of B. tabaci from the desert southwest have
previously not been capable of inducing typical silverleaf (1). Recent
isolations of B. tabaci from California desert regions have shown these
populations to be a mixture of biotypes that differ in a number of
ways, including ability to induce silverleaf of squash. The physiological
differences of the newly introduced whitefly biotype, including host
preference, larval development, and induction of silverleaf symptoms,
clearly distinguish it from the common biotype. Double-stranded RNA
bands were not detected from nymph-infested leaves or from symptomatic
tissue, suggesting that whitefly-induced silverleaf in California
is similar to a systemic phytotoxemia. The occurrence of the silverleaf-inducing
whitefly biotype on nursery stock, including poinsettia and
hibiscus, in various parts of the state and the movement of such nursery
stock from Florida to California are the probable vehicles for
introduction of this new disease problem in California. |