JANUARY | FEBRUARY 2015
Almond Facts 45
Mummies infected with bacterial
spot are the source of disease
inoculum the following spring.
Included are the updated effcacy ratings and timings of
various fungicides for bloom time diseases. Remember to
rotate chemistries to avoid back-to-back applications of
the same mode of action or FRAC group. There is a lot of
information regarding bloom spray timings and diseases at
www.thealmonddoctor.com and www.ucipm.ucdavis.edu.
Bacterial Spot Control for Affected
Orchards
This is a new disease to orchards in California. Predominantly
found in the northern San Joaquin Valley and severely
affecting 'Fritz,' this bacterial disease kills nuts leading to crop
loss. Symptoms appear similar to leaf footed plant bug, but
gumming is amber in color, which when scraped away, reveals
a 1/4-inch lesion. Leaves can also be infected.
The bacteria overwinters in infected mummies and will spread
to the new crop when warm, rainy weather occurs. Recent
research has demonstrated that delayed dormant copper
and mancozeb applications can reduce in-season infection
rates. In season treatments with low doses of copper and
mancozeb were most effective when timed around warm
rain events. A recent study has shown a delayed dormant
(copper-mancozeb) and a single in-season treatment (copper
alone or copper+mancozeb) in mid-March timed before a
warm rain event provided excellent control. Keep in mind
that almond trees are sensitive to high rates of copper. More
information can be found here: http://thealmonddoctor.
com/2015/01/01/bacterial-spot-of-almond-management/
Be Careful with Bees
There has been a lot of concern about honeybee health
related to fungicide and insecticide applications within
orchards. More is being learned every year about the impacts
of pest management practices on hive health. Recently, The
Almond Board of California released an excellent resource
titled "Honey Bee Best Management Practices for California
Almonds (http:// Almonds.com/BeeBMPs)." This resource
provides an overview of the research conducted and the
recommendations generated from the results and conclusions.
The following is a brief overview of these practices that are
associated with insect and disease control around bloom:
• Read the pesticide label carefully - including surfactants -
and avoid any chemicals that indicate toxicity to bees.
• Avoid applying or tank mixing any insecticides during
bloom until the effects on bees are known. Treatments for
peach twig borer should be considered prior to bee move-in
or after hive removal (i.e. delayed dormant, "May" spray);
• Avoid the fungicides iprodione, captan or ziram. These
fungicides negatively impact bee hive health;
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