Biology Reference
In-Depth Information
nonmotile with
a
few exceptions
( C.
Control Use certified seed, a 2-or 3-year rota-
tion; clean up tomato refuse at end of season and
diseased plants throughout season. Fermenting
tomato pulp for 4 days at a temperature near
70 F will destroy bacteria on surface of seed;
hot-water treatment, 25 min at 122 F will kill
some, perhaps not all, of internal bacteria. Start
seedlings in soil that has not previously grown
tomato.
Clavibacter poinsettiae (see Curtobacterium
flaccumfaciens pv. poinsettia ). Stem Canker and
Leaf Spot of Poinsettia, a relatively new disease,
first noted in greenhouses in 1941.
Clavibacter sepedonicum (see Clavibacter
michiganense subsp. sepedonicum ). Bacterial
Ring Rot of potato, widespread since 1931,
when it probably was introduced from Europe.
Clavibacter michiganense subsp.
sepedonicum (formerly Clavibacter
sepedonicum ). Bacterial Ring Rot of potato,
widespread since 1931, when it probably was
introduced from Europe. All commercial varie-
ties are susceptible, with losses formerly in mil-
lions of dollars in decay of tubers in field and
storage. Now a single infected plant in a potato
field disqualifies the whole field for certification.
Symptoms appear when plants are nearly full
grown, with one or more stems in a hill wilted
and stunted while the rest seem healthy. Lower
leaves have pale yellow areas between veins;
these turn deeper yellow, and margins roll
upward. A creamy exudate is expelled when the
stem is cut across. This bacterium may also occur
in sugar beet which are symptomless.
Tuber infection takes place at the stem end,
and the most prominent symptoms appear some
time after storage. The vascular ring turns creamy
yellow to light brown, with a crumbly or cheesy
odorless decay followed by decay from second-
ary organisms. Bacteria are not spread from plant
to plant in the field, but by cutting knife and
fingers at planting. A knife used to cut one
infected tuber may contaminate the next 20 seed
pieces.
Control Use certified seed potatoes. Use several
knives and rotate them in disinfestant. Commer-
cial growers use a rotating knife passed through
a chemical or hot-water bath between cuts.
flaccumfaciens
and C. poinsettiae ). Gram-
positive.
Clavibacter agcopyri (see Corynebacterium
agcopyei ). Yellow Gum Disease on western
wheat grass.
Clavibacter fascians (see Rhodococcus
fascians ). Fasciation , widespread on sweet pea,
also on carnation, chrysanthemum, gypsophila,
geranium, petunia,
impatiens, Hebe sp. and
pyrethrum.
Clavibacter flaccumfaciens (see
Curtobacterium flaccumfaciens pv.
flaccumfaciens ). Bacterial Wilt of bean, wide-
spread on kidney and lima beans and soybean,
causing considerable loss.
Clavibacter humiferum (see Corynebacterium
humiferum ). Reported from wetwood of poplar,
in Colorado.
Clavibacter michiganense (see Clavibacter
michiganense subsp. michiganense ). Bacterial
Canker of Tomato, widespread, formerly causing
serious losses of tomato canning crops.
Clavibacter michiganense subsp.
michiganense (formerly Clavibacter
michiganens ). Bacterial Canker of Tomato, wide-
spread, formerly causing serious losses of tomato
canning crops. The disease has now been
reported on browallia, brunfelsia, cestrum,
Datura sp., eggplant, Jerusalem-cherry,
bittersweet, pepper, painted-tongue, potato,
ground-cherry, and butterfly-flower in Wyoming.
This is a vascular wilt disease, seedlings
remaining stunted. Symptoms on older
plants start with wilting of margins of lower leaf-
lets, often only on one side of a leaf. Leaflets curl
upward, brown, and wither, but remain attached
to stem. One-sided infection may extend up
through the plant and open cankers from pith to
outer surface of stem. Fruit infection starts
with small, raised, snow-white spots, centers
later browned and roughened but the white color
persisting as a halo to give a bird's-eye
spot. Fruits can be distorted, stunted, yellow
inside. In the field, bacteria are spread by
splashed rain and can persist in soil 2 or more
years. Seeds carry the bacteria internally as well
as externally.
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