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Almond Facts
JANUARY | FEBRUARY 2017
Untimely rains in spring and early summer
2016 triggered the onset of almond diseases that
were not widely seen during the drought years.
That was the observation of Roger Duncan, UC
Cooperative Extension, Stanislaus County, at
Blue Diamond’s
2016 Annual Meeting.
“Maybe the drought made us complacent,” he said.
“We had gotten used to not having a lot of rain, maybe
we didn’t put on the third or fourth fungicide spray
like we used to.”
Recapping the season, he said, “The first two weeks of
March we had quite a bit of rain, which set us up for the
Green Fruit Rot/Jacket Rot that we typically do not see.
Then we had more rain in April which made conditions
ripe for summer-type diseases.”
Duncan reviewed the most problematic diseases, their
symptoms and recommended treatments.
Jacket Rot/Green Fruit Rot
(Botrytis cinerea)
Botrytis infects the flower, which is very susceptible.
Once it establishes itself it spreads to the nuts and then
into the stem, twig and spur, leading to loss of adjacent
leaves, said Duncan. “Botrytis spores are everywhere.
They colonize in dying flower parts or leaves. In the right
conditions – wet, cool weather – infections can occur
anytime from late bloom to immature nut stage.”
Citing UC Extension sources, Duncan said full bloom is the
best timing for fungicide treatment for green fruit rot. “But
in a year like 2016, when we continued to have rain after
bloom, another treatment at petal fall or even a little later
would have been effective for the kind of outbreak we had.”
Almond Scab
(
Cladosporium carpophilum)
Several almond varieties are susceptible to scab, Duncan
noted. He described it as a little, velvety, olive-colored
lesion that grows very slowly. It also appears on the hull.
Avoiding Disease
in Almonds
