Biology Reference
In-Depth Information
other fruit. Seed is infected internally and con-
taminated externally. Harvest seed only from
healthy fruit.
Glomerella cingulata (formerly
Colletotrichum erumpens ). Rhubarb Anthrac-
nose , Stalk Rot . Oval, soft watery spots on petioles
increase until whole stalks are included; leaves wilt
and die. Small dark fruiting bodies with setae sur-
vive winter in stems, produce conidia in spring.
Clean up all rhubarb remains in fall.
Glomerella cingulata (formerly
Colletotrichum antirrhini ). Snapdragon
Anthracnose on snapdragon, chiefly in green-
houses, sometimes outdoors in late summer.
Stems have oval, sunken spots, grayish white
with narrow brown or reddish borders, fruiting
bodies showing as minute black dots in center.
Spots on leaves are circular, yellow green turning
dirty white, with narrow brown borders. Stem
cankers may coalesce to girdle plant at base,
causing collapse of upper portions, with leaves
hanging limp along the stem.
Control Take cuttings from healthy plants; provide
air circulation; keep foliage dry; destroy infected
outdoor plants in autumn. Spray, every 7 to 10 days.
Glomerella cingulata (formerly
Colletotrichum phomoides ). Tomato Anthrac-
nose , common rot of ripe tomatoes, most frequent
in Northeast and North Central districts. Symp-
toms appear late in the season, causing more loss
to canning crops. Small, circular sunken spots,
increasing to an inch in diameter, penetrate deeply
into the flesh. At first water-soaked, the spots turn
dark, with pinkish, cream, or brown spore masses
in the depressed centers, often arranged in concen-
tric rings. The disease is worse in warm, moist
weather. The fungus winters in tomato refuse,
sometimes in cucumber and melon debris.
Control Clean up trash and rotting fruit.
Glomerella glycines Fruit Anthracnose of
tomato. Also, anthracnose on soybean.
Glomerella gossypii Fruit Anthracnose of
tomato. Also, anthracnose on cotton.
Glomerella lindemuthianum (formerly
Colletotrichum lindemuthianum ). Bean Anthrac-
nose , a major bean disease, sometimes mistakenly
called “rust,” generally present in eastern and cen-
tral states, rare from the Rocky Mountains to the
Pacific Coast. It may also affect lima bean, Scarlet
runner, tepary, mung, kudzu, and broad beans, and
cowpea. It is worldwide in distribution, known in
the United States since 1880. There are at least 34
strains of the fungus, in three different groups, but
the disease has decreased in importance with the
use of western-grown, anthracnose-free seed.
The most conspicuous symptoms are on the pods,
small, brown specks enlarging to black, circular,
sunken spots, in moist weather showing the typical
pinkish ooze of the slime-spores. Older spots often
have narrow reddish borders. After the spores are
washed away, the acervuli look like dark pimples. If
pods are infected when young, the disease extends
through to the seed, which turns yellow, then rusty
brown or black under the pod lesion. The infection
may extend deep enough to reach the cotyledons.
Leaf lesions are dark areas along veins on underside
of the blade and on petioles. Seedlings may show
stem spotting below diseased cotyledons. The fun-
gus is spread by splashing rain, tools, and gardeners
working with beans when they are wet. Optimum
temperature is between 63 and 75 F, with maxi-
mum around 85 F.
Control Use western-grown seed. Saving home-
grown seed is dangerous unless you can be sure of
selecting from healthy plants and pods. Clean up,
or spade under, old bean tops; rotate crops. Never
pick or cultivate beans when vines are wet. There
are some resistant varieties, but more reliance
should be placed on obtaining seed grown
where the disease is not present.
Glomerella nephrolepidis Fern Anthracnose ,
Tip Blight of Boston and sword ferns. The soft
growing tips of fronds turn brown and dry. Keep
foliage dry; remove and burn diseased leaves.
Gnomonia
Ascomycetes, Diaporthales
Perithecia innate, beaked, separate; paraphyses
absent; ascospores two-celled, hyaline;
anamorph state Gloeosporium or Marssonina .
Diseases caused by Gnomonia are classified as
anthracnose, scorch, or leaf spot.
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