| Brown rot in stone fruits such as apricots, cherries,
nectarines, peaches, and plums is caused by
Monilinia fructicola. Brown rot is the most
destructive stone-fruit disease in the U.S.
Symptoms and Diagnosis
Plants infected with brown rot will develop brown,
sunken cankers on the twigs; gummy sap will ooze
out of these cankers. Infected twigs die. Young fruit
will develop small, circular, brown spots. As the fruit
develops, the spots enlarge and may cover the entire
fruit. These spots can become covered with fuzzy
gray spores after rainy weather. When infected fruit
are sliced open, the flesh will be brown, dry, and
firm. Fruit may either drop prematurely or remain in
the tree past harvest time to brown completely and
shrivel into mummified form.
Life Cycle
Fungal spores overwinter in twig cankers or the
mummified fruit either on the ground or on the tree.
With the help of the wind and rain, spores may
infect healthy flower buds the next spring. After
infecting the flowers, the fungus grows into the
twigs. Moist weather encourages this growth into the
twigs and gummy sap will ooze from lesions formed
there. Spores will also develop on the lesions and
infect the maturing fruit which are more susceptible
than the younger fruit.
Integrated Pest Management Strategies
1. Prune infected twigs. Pick off rotted fruit. Clean
up fallen fruit before and during harvest. Remove
and destroy all unharvested fruit during the
dormant period.
2. Apply fungicides at the proper time. The critical
times to manage brown rot are the first three
weeks after petal fall and the last three weeks
before harvest. Pesticides registered for use
include copper, captan, cyfluthrin, iprodione
(Chipco), maneb, sulphur, thiophanate methyl
(Cleary 3336), thiram, and ziram. Apply sulfur just
before harvest.
3. Plant fruit tree varieties that are resistant to
the disease:
Cherry: ‘Stark Gold’ or ‘Northstar Tart’.
Peach: ‘Carmen’, ‘Elberta’, or ‘Orange Cling’. |
