Biology Reference
In-Depth Information
protection is removed. Experimental spraying
with antibiotics - streptomycin, terramycin, and
neomycin has reduced wilt and increased yield.
Pantoea ananatis,
Leaf Blight
and
Bulb
Decay
of onion.
Pantoea herbicola (formerly
Erwinia
herbicola
).
Leaf Spot
of dracaena. On Dracaena
sanderana, gypsophila and related plants. Galls
are formed at crown and roots of grafted plants
from 1/4 to 1 inch in diameter, but with a flat
nodular growth rather than the usual globose
crown gall.
Pantoea stewartii (formerly
Erwinia stewartii
).
Bacterial Wilt
of corn,
Stewart's Disease
on sweet
corn, sometimes field corn, in the middle regions
of the United States, from New York to Califor-
nia. This is a vascular disease with yellow slime
formed in the water-conducting system, resulting
in browning of nodes, and dwarfing of plants; or
long pale green streaks on leaf blades, followed
by wilting and death of whole plant. Tassels may
be formed prematurely and die before the rest of
the plant. The bacteria are chiefly disseminated
by corn flea beetles, and winter either in the
beetles or in seed. Primary infections come from
flea beetles feeding in spring, from infected seed,
and occasionally from soil; but secondary spread
is mostly by insects.
Corn grown in rich soil is more susceptible to
wilt, and so are early varieties, especially Golden
Bantam. Winter temperatures influence the
amount of wilt the following summer. If the win-
ter index, which is the sum of mean temperatures
for December, January, and February, is above
100, bacterial wilt will be present in destructive
amounts on susceptible varieties. If the index is
below 90, the disease will be very sparse in
northeastern states; if the index is between 90
and 100, there will be a moderate amount of
wilt. Disease surveys over a period of years tes-
tify to the reliability of such forecasts (based on
the amount of cold the flea beetle vectors can
survive); but with the increasing use of hybrid
sweet corn resistant to wilt, the importance of
winter temperatures is reduced.
Control
Use insecticides to control flea beetles;
substitute commercial fertilizer for manure;
destroy infected refuse; try treating seed with
terracmycin or streptomycin. Use resistant varie-
ties such as Golden Cross Bantam, Carmel-cross,
Ioana, Marcross, and Iochief.
Pseudomonadaceae
Pseudomonas
Motile with polar flagella; straight or curved rods;
Gram-negative. Many species produce
a greenish, water-soluble pigment. Many species
are found in soil and water; many are plant path-
ogens causing leaf spots or blights.
Acidovorax avenae formerly
Pseudomonas
albopreciptans
).
Bacterial Spot
of cereals,
grasses, and corn. Light or dark brown spots or
streaks on grass blades. Bacteria enter through
stomata or water pores.
Acidovorax avenae (formerly
Pseudomonas
avenae
).
Bacterial Leaf Spot
of sweet corn.
Bac-
terial Leaf Blight
of johnsongrass.
Acidovorax avenae subsp. citrulli (formerly
Pseudomonas pseudoalcaligenes
).
Angular Leaf
Spot
of muskmelon and watermelon. Fruit
blotch;
on melon,
squash,
pumpkin,
and
watermelon.
Acidovorax cattleyae (formerly
Pseudomonas
cattleyae
).
Brown Spot
of orchids,
Phalaenopsis
and
Cattleya
, common in greenhouses. Infection
is through stomata of young plants, wounds of
older plants. Dark green, circular water-soaked
spots change to brown and finally black. On
Cat-
tleya
the disease is limited to older leaves.
Burkholderia andropogonis (formerly
Pseu-
domonas and ropogonis
).
Bacterial Stripe
of sor-
ghum and corn.
Bacterial Leaf Spot
on
bougainvillea.
Black Spot
on clovers and statice.
Also causes blight of chickpea, and bacterial leaf
spot on white clover. Red streaks and blotches
appear on leaves and sheaths, with abundant exu-
date drying down to red crusts or scales, readily
washed off
in rains. Bacteria enter
through
stomata.
Bacterial Leaf Spot
of velvet bean, clovers.
Translucent angular brown leaf spots have lighter
centers and chlorotic surrounding tissue; there is
