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How to Manage Pests
UC Pest Management Guidelines
Almond
Scab
Pathogen: Cladosporium
carpophilum
(Reviewed 1/05,
updated 1/05)
In this Guideline:
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Greyish black, soft looking spots form on leaves, fruit, and twigs. Young
lesions are indistinct small yellow
specks, best seen by holding a leaf up to the light. Lesions usually are
not visible until late spring or early summer.
The fungus survives in twig lesions,
and spores are spread by wind or rain. The disease is favored by prolonged wet
spring weather, and is most prevalent in the Sacramento Valley. Severe scab
infections cause early defoliation; if left uncontrolled for several years,
infected trees become weakened. The disease often occurs in sprinkler-irrigated
orchards where water reaches foliage.
Scab may be controlled by shothole sprays. However, a scab treatment may be
required if rain occurs into mid- to late spring. One application as late as 5
weeks after petal fall can protect against scab, but an earlier application (2
weeks after petal fall) may improve control.
| 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. |
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DORMANT |
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| A. |
LIME SULFUR# |
8 gal/100 gal water |
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COMMENTS: Chemical class: inorganic. Can improve
spring control of scab, especially if a wet spring delays treatment. |
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BLOOM |
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| 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. |
AZOXYSTROBIN |
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(Abound) |
11-15.4 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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| C. |
TRIFLOXYSTROBIN |
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(Flint) |
3-4 oz |
60 — see comments |
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COMMENTS: Chemical class: strobilurin. Do not apply
within 60 days of harvest or after hull split. Do not exceed more than 3
applications of all strobilurins per season to limit the potential for the
development of resistance. Do not apply more than 12 oz/acre/season. |
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| D. |
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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| E. |
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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| F. |
ZIRAM 76DF |
8 lb |
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COMMENTS: Chemical class: carbamate (dimethyl
dithiocarbamate). Do not apply more than 32 lb/acre/season. |
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| G. |
THIOPHANATE-METHYL |
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(Topsin-M) 70WP |
1.5-2 lb |
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COMMENTS: Chemical class: benzimidazole. Strains of scab pathogen resistant to thiophanate-methyl may occur.
Do not apply more than
once a year. |
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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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