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How to Manage Pests
UC Pest Management Guidelines
Almond
Brown
Rot Blossom Blight
Pathogen: Monilinia
laxa; rarely Monilinia fructicola
(Reviewed 1/05,
updated 1/05)
In this Guideline:
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Young blossom spurs and associated leaves collapse to form shoot blight. Gum
may exude at the base of infected
flowers. Cankers on blighted
twigs have tan centers with dark margins. At high humidity, gray to tan spore masses form on diseased flower parts and
twig cankers.
Flowers may become infected from pink bud to petal fall and are most susceptible when fully open. In almonds, stigma,
anthers, and petals are all very susceptible to infection.
The fungus survives in twig cankers
and on remaining diseased flower
parts and spurs. Spore pads (sporodochia) appear on these structures in
late winter to provide inoculum for spring infection. Spores are airborne or
rain splashed. Infection is favored by rainy weather with temperatures in the
mid-70s during bloom.
Control is based upon protection of flower parts. Ideally, applications should
be made for each cultivar according to its stage of bloom. Otherwise, timing
should be determined by the bloom of the most seriously affected cultivar in
the orchard.
Treat at pink bud (5-10% bloom) and/or full bloom. One application at pink bud
is sufficient in most orchards in most years if there is no rain. If brown rot
has been severe or in years of extended bloom accompanied by rainfall, a second
or even third application near full bloom may be necessary.
| Common name |
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P.H.I.+ |
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| (trade name) |
Amount/Acre |
(days) |
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| Fungicides are listed in general order of efficacy. |
| A. |
BOSCALID/PYRACLOSTROBIN |
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(Pristine) |
10.5-14.5 oz |
see comments |
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COMMENTS: Chemical class: carboxyanilide/strobilurin.
See label for current preharvest interval. Do not make more than 4 applications
per season of strobilurins or carboxyanilides to limit the potential for the
development of resistance. |
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| B. |
IPRODIONE |
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(Rovral) 50WP, 4F |
1 lb |
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COMMENTS: Chemical class: dicarboximide. Addition of
a narrow range oil (superior, supreme) at 1 to 2% volume/volume increases the
effectiveness of this material. Do not apply oil, however, within 3 weeks of a
sulfur application or closely before or after an application of captan or
chlorothalonil. Do not apply more than 4 applications/season. |
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| C. |
THIOPHANATE-METHYL |
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(Topsin-M) 70WP |
1.5-2 lb |
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COMMENTS: Chemical class: benzimidazole. Strains of
brown rot pathogen resistant to thiophanate-methyl have been found on almond,
but resistance is not widespread. Do not apply more than 3 lb/season/acre. |
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| D. |
CYPRODINIL |
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(Vangard) WG |
5 oz |
150 days |
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COMMENTS: Chemical class: anilinopyrimidine. Do not
apply more than 30 oz/acre/crop/year. |
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| E. |
AZOXYSTROBIN |
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(Abound) 2F |
12.3-15.4 oz |
28 |
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COMMENTS: Chemical class: strobilurin. Do not apply
more than 3 sequential sprays before alternating with a fungicide that has a
different mode of action. Do not apply more than 4 applications of strobilurin
fungicides/year or apply more than 1.92 qt/product/acre/season. |
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| F. |
FENHEXAMID |
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(Elevate) 50 WDG |
1-1.5 lb |
0 |
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COMMENTS: Chemical class: hydoxyanilide. Apply in
sufficient water to obtain complete coverage of flowers and twigs. Do not make
more than 2 consecutive applications or apply more than 6 lb/acre/season. |
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| G. |
MYCLOBUTANIL |
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(Laredo) EC |
8-12.8 fl oz |
90 |
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COMMENTS: Chemical class: demethylation (sterol)
inhibitor-triazole. Apply in 400 gallons water/acre. Do not make more than 3
applications or apply more than 38.4 fl oz/acre/season. |
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| H. |
CAPTAN |
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(various) 50WP |
8 lb |
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COMMENTS: Chemical class: phthalamide. See label for
preharvest interval, which varies depending on formulation and if hulls are to
be fed to livestock. Do not apply in combination with, immediately before, or
closely following oil sprays. |
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| I. |
MANEB |
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(various) |
Label rates |
145 |
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COMMENTS: Chemical class: carbamate (ethylene
bisdithiocarbamate). Do not apply more than 32 lb of product/acre/season. |
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More information on almond fungicides
![[Precautions]](/IMAGES/btn-precautions_bul.gif)
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg)
UC IPM Pest Management Guidelines: Almond
UC ANR Publication 3431
Diseases
W. D. Gubler, Plant Pathology, UC Davis
J. E. Adaskaveg, Plant Pathology, UC Riverside
Roger Duncan, UC Cooperative Extension, Stanislaus County
J. J.
Stapleton, UC IPM Program, Kearney Agricultural Center
Acknowledgment for contributions to the disease section:
B. L. Teviotdale, Kearney Agricultural Center, Parlier
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