TIME TO CONSIDER
I hope you all had a wonderful holiday season and a great start to the New Year. The winter was dry, but hopefully adequate
rains will begin to fall. The lack of rain and warmer days may accelerate bloom, which may mean that bloom will occur earlier
than last year, with a similar timing to 2015. Cooler conditions, however, will delay bloom. With that in mind, below are some
considerations for your operations.
Fungicide Sprays
Bloom will begin in early to mid-February and extend
through March. Due to almond flower sensitivity to
disease and weather conditions conducive for disease,
most people will spray a fungicide during this period. In
wet conditions, multiple sprays may be needed, while in
dry years zero to one spray may suffice. Conditions that
favor disease formation include rain or heavy dew, and
warmer temperatures for Brown Rot, Anthracnose, Bacterial
Spot, and Shot-hole, and cool, wet weather for Jacket-
rot. Fungicide selection should provide coverage for the
diseases of concern (see the fungicide efficacy table).
Since most fungicides work to protect the plant from
being infected by killing the germinating spore, bloom
sprays should be applied before rain events to provide
protection for flowers, flower parts, and emerging
leaf tissue. Some chemistries, such as FRAC groups 3
and 11 are able to move through the epidermis of the
plant’s leaves or flowers. This provides a slight curative
component to these powerful fungicides and makes them
a great option if a spray was missed by one to two days
or there wasn’t enough time to cover the acreage prior to
the rain event.
Coverage from a fungicide spray will last around two
weeks, unless significant rainfall occurs. If applying
prior to a rain event, applications will need a few hours
to dry to prevent “run-off.” In rainy weather, follow-up
sprays will be needed every seven to ten days. Some
varieties — such as ‘Butte’ and ‘Carmel’ — are more
susceptible to disease and may require a spray even
in dry weather, while others — such as ‘Nonpareil’
are quite tolerant and may not need a bloom spray.
Orchard history, weather, and your comfort level
should be the guidance in determining your bloom and
springtime disease control strategy.
A fungicide program should be developed prior to
bloom. Programs should be developed to prevent back-
to-back application of fungicides within the same mode
of action. Mode of actions is simplified into a FRAC
number; therefore avoid back-to-back applications of the
same FRAC number. This includes pre-mixed fungicides.
An example of a rotation program for a multiple sprays
for rainy weather include: First Spray: FRAC 9 (Scala,
Vanguard), 2nd Spray: FRAC 11 or FRAC 7/11 (Gem,
Abound, Pristine, Luna Sensation, Merivon, etc), 3rd Spray:
FRAC M4 (Chlorothalonil), 4th spray: FRAC 3, FRAC 11,
or FRAC 3/11 (Bumper, Tilt, Gem, Abound, Indar, Quadris
Top, Quilt Xcel, etc). Note how the two applications of
FRAC 11 were split by rotating away to another chemistry.
Disclaimer: the fungicides listed are an example, not an
endorsement for use. Please refer to Timing and Efficacy
Tables for full list of tested fungicides (see fungicide
efficacy table on pages 38 and 39). There are many
effective fungicides not listed in this example.
For further information regarding bloom spray timings
and diseases, please see the
and ucipm.ucdavis.edu.
Insecticide Applications at Bloom for Peach Twig
Borer (PTB)
Recent research has found that applications of some
insecticides timed at bloom has a negative impact on
bee health. Tank mixing of products should be avoided.
Alternatively, research done over 20 years ago has
found that Bacillus thuringiensis (Bt) can be applied at
bloom to effectively control PTB without impacting bees.
IN YOUR ORCHARD
3 6
A L M O N D F A C T S
