Agriculture Reference
In-Depth Information
the newly emerging leaves, shoots, and blossoms. Spores from these infected
plant parts later cause secondary infections.
Management.
These diseases are easily controlled with a fall spray of
Bordeaux mix, followed by a spring dormant spray of Bordeaux mix or lime
sulfur. If the diseases do develop, thin the fruits heavily and follow normal
practices to maintain healthy trees. Avoid excessive irrigation and fertiliza-
tion that might force late growth that would be susceptible to winter injury.
Care for the trees, and prepare for next year's crop.
Peach Scab
Peach scab resembles apple scab but is caused by a different fungus (
Cla-
dosporium carpophilum
). Rare in arid and semiarid regions, peach scab
can become serious in humid climates, particularly in the Mid-Atlantic and
southeastern states. Warm, wet days during midseason greatly increase the
risk of the disease, which also infects apricots and nectarines.
Symptoms.
Although the fungus also attacks the stems, symptoms are most
visible on the fruits. Small greenish spots gradually enlarge, merge, and be-
come blackened. The lesions often crack open, exposing the interior of the
fruits to rot organisms. The disease overwinters in lesions on the most re-
cently developed twigs and stems. By early the following season, these le-
sions appear grayish in color and slightly sunken.
Spores from the stem lesions develop in early spring and are splashed
by rain onto young fruits and shoots. Water is required for infection. For-
tunately, an incubation period of 40 to 70 days is required for symptoms to
develop. Except in very late-season varieties, only infections that occur prior
to pit hardening are likely to appear before harvest.
Management.
Use all of the practices we have discussed to avoid humid
conditions and create an open, well-pruned canopy with good air movement.
