Bacterial Wilt of Diploid Musa Caused by Pseudomonas solanacearum Race 1 in Australia. E. Akiew, Plant Pathology Branch, Queensland Department of Primary Industries, Mareeba, Queensland 4880, Australia. . Plant Dis. 76:753. Accepted for publication 20 February 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/PD-76-0753C.
In March 1991, race 1 of Pseudomonas solanacearum (Smith) Smith
was isolated from diseased Musa shizocarpa Simm., a diploid banana
species introduced to Australia from Papua New Guinea for breeding
purposes. The plants were derived from tissue culture and grown among
several banana breeding lines in a field nursery at South Johnston
Research Station, North Queensland. Diseased plants had irregular,
soft patches of black rot on the pseudostem, dark brown to black
necrotic lesions in the vascular tissues, and droplets of brown, slimy
bacterial ooze on cut surfaces of the pseudostem. The bacterium had
high tyrosinase activity on tyrosine-supplemented medium and oxidized
mannitol, sorbitol, dulcitol, cellobiose, maltose, lactose, and
trehalose. Colonies were irregularly round, fluidal, and creamy white
with pink-orange centers on Kelman's tetrazolium medium. These
strains were not pathogenic on triploid banana (cv. Williams) but were virulent on seedlings of diploid bananas M. shizocarpa, M.
acuminata subsp. banksii Simm., and M. lolodensis Chee. and on
seedlings of Lycopersicon esculentum Mill., Solanum melongena L.,
and Arachis hypogaea L. 'Red Spanish'. The strains were considered
race 1. The banana cultivars were also susceptible to a number of
P. solanacearum race 1 strains from nonmusaceous hosts. On
inoculated seedlings of Sucrier (AA), a cultivated form of M. acuminata,
the banana isolates did not induce bacterial wilt symptoms except
yellowing of leaves and stunted growth, whereas isolates from
Heliconia from nurseries in adjacent localities caused severe wilt.
Certain race 1 strains of P. solanacearum in Australia appear to be
pathogenic on some musaceous hosts, and I believe these strains would
be found in some wild diploid banana species in the region. This
is the first report of bacterial wilt of diploid banana in Australia
and outside Latin America (1).