Biology Reference
In-Depth Information
Oleander Bacterial Gall
. Galls or tumors are
formed on branches, herbaceous shoots, leaves,
and flowers but not on underground parts. Small
swellings develop on leaf veins, surrounded by
yellow tissue, with bacterial ooze coming from
veins in large quantity. Young shoots have longi-
tudinal swellings with small secondary tubercles;
young leaves and seedpods may be distorted and
curled. On older branches tumors are soft or
spongy and roughened with projecting tubercles;
they slowly turn dark. Prune out infected por-
tions, sterilizing shears between cuts; propagate
only from healthy plants.
Pseudomonas syringae pv. tabaci (see
Pseudo-
monas tabaci
).
Blackfire
of tobacco.
Pseudomonas syringae pv. tabaci
Tobacco
Wildfire
on tobacco, tomato, eggplant, soybean,
cowpea, pokeberry, and ground-cherry, in all
tobacco districts sporadically. Leaf spots have
tan to brown dead centers with chlorotic halos.
The disease appears first on lower leaves and
spreads rapidly in wet weather. The bacteria per-
sist a few months in crop refuse and on seed and
enter through stomatal cavities. In buried soybean
leaves the bacteria have lived less than 4 months;
so fall plowing may be beneficial. Seed stored for
18 months produces plants free from wildfire.
Pseudomonas syringae pv. tagetis
Bacterial
Leaf Spot
. Circular necrotic lesions on leaves and
petioles. The lesions have dark purple margins. This
disease occurs on marigold, sunflower, Jerusalem
artichoke, and common ragweed. Apical chlorosis
is also caused by this pathogen on sunflower and
sunflower seed may be a source of inoculum.
Pseudomonas syringae pv. tagetis
Bacterial
Leaf Spot
on compass plant and sunflower.
Pseudomonas syringae pv. tomato
Bacterial
Leaf Spot
of crucifers,
Pepper Spot
of cabbage,
cauliflower, Chinese cabbage, and turnip, mostly
in northeastern and Middle Atlantic states.
Numerous brown or purple spots range from pin-
point to 1/8 inch in diameter. If spots are very
numerous, leaves yellow and drop off. Cauli-
flower is more commonly affected than cabbage.
Bacteria, disseminated on seed or in diseased
plant parts, enter through stomata, and visible
symptoms appear in 3 to 6 days. Disease is most
severe in seedbeds.
Control
Change location of hotbed starting
seedlings; use 2-year rotation in field; have seed
hot-water treated.
Pseudomonas syringae pv. tomato
Bacterial
Speck
of tomato. Numerous, dark brown raised
spots on fruit are very small, less than 1/16 inch;
they do not extend into flesh and are more
disfiguring than harmful.
Pseudomonas syringae pv. zizaniae
Leaf Spot
and
Stem Spot
of wild rice.
Pseudomonas tabaci (see
Pseudomonas
syringae
pv.
tabaci
).
Blackfire
of tobacco.
Pseudomonas viburni
Bacterial Leaf Spot
of
viburnum, widespread. Circular water-soaked
spots appear on leaves, and irregular sunken
brown cankers on young stems, and the bacteria
overwinter in leaves, stems or buds. Remove and
burn infected leaves. Spray with bordeaux mix-
ture or an antibiotic such as Agrimycin two or
three times at weekly intervals.
Pseudomonas viridiflava
Bacterial Leaf Spot
on basil.
Bacterial Canker
on poinsettia.
Pseudomonas viridilivida
Louisiana Lettuce
Disease
on lettuce, bell pepper, and tomatoes.
Numerous water-soaked leaf spots fuse to infect
large areas, first with a soft rot, then a dry shriv-
eling. Sometimes outer leaves are rotted and the
heart sound. This bacterium also causes greasy
canker of poinsettia.
Pseudomonas washingtoniae This bacterium
causes spots on leaves of Washington palm.
Pseudomonas woodsii
Bacterial Spot
and
Blight
of carnation. Leaf lesions are small,
elongated, brown with water-soaked
borders, withering to brown sunken areas, with
masses of bacteria oozing out of stomata. They
are spread in greenhouses by syringing, and out-
doors by rain. Follow cultural practices suggested
under
P. caryophylli
for carnation wilt.
Pseudomonas sp.
Blueberry Canker
reported
from Oregon. Reddish brown to black cankers
appear on canes of the previous season; all buds in
the cankered areas are killed; stems are sometimes
girdled. Varieties Weymouth, June, and Rancocas
are resistant, but Jersey, Atlantic, Scammel,
Coville, and Evelyn are highly susceptible.
Rhizomonas
suberifaciens
Corky
Rot
on
lettuce.
