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Anthracnose
(fungus - Colletotrichum gloeosporioides): The initial symptoms are watersoaked,
sunken spots one-quarter to one inch in diameter on fruit [Photo].
The centers of these spots later turn black and then pink when the fungus produces
spores. The flesh beneath the spots becomes soft and watery, which spreads to
the entire fruit. Small, irregular-shaped watersoaked spots on leaves may also
be seen. These spots eventually turn brown. In the climate of south Texas, cultural
control measures should be sufficient for control of this disease in the home
garden. These measures include removing the fruit as soon as it matures, removing
all dead leaves and fruit from the vicinity of the plants, and removing infected
fruits from the trees. Under conditions of severe disease pressure that would
be found in more rainy, humid climates, fungicides may be used.
Black
Spot (fungus - Asperisporium caricae): The initial symptoms are water-soaked
spots on the upper leaf surface. Later, small, black spots are visible on the
underside of the leaf [Photo].
Black spots may also be found on the fruit. The tissue beneath them becomes
corky, but the fruit does not rot. If there is a high incidence of infection
of young leaves, a fungicide may be used.
Collapse of Mature Plants (unknown cause): This disease has been reported in the Rio Grande Valley. One of the symptoms is a sudden weakening of petioles that causes the leaves to droop close to the stem. The roots or stems of such plants often show a watery brown rot and the plants eventually die. The cause has not been determined, but fungi such as Rhizoctonia and Fusarium have been isolated from roots. The disease has been associated with waterlogged soil and poor soil drainage.
Damping-Off (fungus - Rhizoctonia solani): This is a disease of young seedlings. Lesions are seen on the stem at or just above soil level. The stem becomes watery and shrinks, followed by death of the plant. Use well-drained soil and avoid overwatering.
Herbicide
Injury: Curling of the leaves was seen with the use of a hormonal herbicide
(2,4-D) applied to a nearby lawn [Photo].
Herbicides may drift with the wind from the area of application to nearby susceptible
plants. Additionally, ester formulations of 2,4-D may volatilize (i.e. become
a vapor after they are applied) and move to non-treated areas. Herbicide injuries
of this type are not likely to cause permanent damage to trees.
Stem Rot (fungus - Pythium sp.): This disease was seen on young transplants. The initial symptom is a watersoaking of the lower stem followed by its disintegration. Plants eventually wilt. Often, the white, cottony growth of the fungus is visible [Photo]. Transplants should be planted in soil with good drainage. Stems should not be banked with soil.
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