|
|
How to Manage Pests
UC Pest Management Guidelines
Almond
Alternaria
Leaf Spot
Pathogen: Alternaria
alternata
(Reviewed 1/05,
updated 1/05)
In this Guideline:
|
|
|
Alternaria leaf spot appears as fairly large brown spots on leaves, about 0.5
to 0.75 (12-18 mm) in diameter. The
spots turn black as the fungus produces
spores. Leaf spot develops most rapidly in June and July, and trees can be
almost completely defoliated by early summer when the disease is severe. The
disease appears to be most severe where dews form, humidity is high, and air is
stagnant.
Alternaria leaf spot can occur on almond trees grown anywhere in the Central
Valley but rarely is it severe enough in the northern San Joaquin Valley to
require treatment. It has been most serious in the southern San Joaquin Valley.
The disease occurs first and is most severe on exposed leaves. Trees trained to
an open and spreading canopy usually have more severe Alternaria leaf spot.
Monitor for signs of the disease in April through June. If monitoring indicates
the presence of Alternaria, begin late spring treatments about mid-April. In
orchards with a history of the disease, treat in mid- to late April and 2 to 3
weeks later.
| Common name |
|
P.H.I.+ |
|---|
| (trade name) |
Amount/Acre |
(days) |
|---|
|
|
|
|
| Fungicides are listed in general order of efficacy. |
| A. |
BOSCALID/PYRACLOSTROBIN |
|---|
| |
(Pristine) |
10.5-14.5 oz |
see comments |
| |
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. |
| |
|
|
|
| B. |
AZOXYSTROBIN |
|
|
|---|
| |
(Abound) |
11-15.4 oz |
28 |
| |
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. |
| |
|
|
|
| C. |
TRIFLOXYSTROBIN |
|
|
|---|
| |
(Flint) |
3-4 oz |
60 — see comments |
| |
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. |
| |
|
|
|
| D. |
IPRODIONE/NARROW RANGE OIL |
|---|
| |
(Rovral) |
Label rates |
|
| |
COMMENTS: Chemical class: dicarboximide. Do not use
later than 5 weeks after petal fall. Not a good choice when disease pressure is
severe because of label timing restrictions. |
| |
|
| E. |
IPRODIONE |
|
|
|---|
| |
(Rovral) 50WP |
1 lb |
|
| |
COMMENTS: Chemical class: dicarboximide. Do not use
later than 5 weeks after petal fall. Do not make more than 4
applications/season. Not a good choice when disease pressure is severe because
of label timing restrictions. |
| |
|
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
Disease
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
Top of page
|
