Page 49 - jan-feb-2015

JANUARY | FEBRUARY 2015 Almond Facts 49
Disease Dormant Bloom Spring1 Summer
Pink bud Full bloom Petal fall 2 weeks 5 weeks May June
Alternaria ---- ---- ---- ---- ---- ++ +++ +++
Anthracnose2 ---- ++ +++ +++ +++ +++ +++ ++
Brown rot ---- ++ +++ + ---- ---- ---- ----
Green fruit rot ---- ---- +++ ---- ---- ---- ---- ----
Hull rot7 ---- ---- ---- ---- ---- ---- ---- +++
Leaf blight ---- ---- +++ ++ + ---- ---- ----
Scab3 ++ --- --- ++ +++ +++ + ---
Shot hole4 +5 + ++ +++ +++ ++ ---- ----
Rust ---- ---- ---- ---- ---- +++ +++ +6
Rating: +++ = most effective, ++ = moderately effective, + = least effective, and ---- = ineffective
1 Two and fve weeks after petal fall are general timings to represent early postbloom and the latest time that most fungicides can be applied. The exact
timing is not critical but depends on the occurrence of rainfall.
2 If anthracnose was damaging in previous years and temperatures are moderate (63°F or higher) during bloom, make the frst application at pink bud.
Otherwise treatment can begin at or shortly after petal fall. In all cases, application should be repeated at 7- to 10-day intervals when rains occur during
periods of moderate temperatures. Treatment should, if possible, precede any late spring and early summer rains. Rotate fungicides, using different
fungicide classes, as a resistance management strategy.
3 Early treatments (during bloom) have minimal effect on scab; the 5-week treatment usually is most effective. Treatments after 5 weeks are useful in
northern areas where late spring and early summer rains occur. Dormant treatment with liquid lime sulfur improves effcacy of spring control programs.
4 If pathogen spores were found during fall leaf monitoring, apply a shot hole fungicide during bloom, preferably at petal fall or when young leaves frst
appear. Re-apply when spores are found on new leaves or if heavy, persistent spring rains occur. If pathogen spores were not present the previous fall, shot
hole control may be delayed until spores are seen on new leaves in spring.
5 Dormant copper treatment seldom reduces shot hole infection but may be useful in severely affected orchards and must be followed by a good spring
program.
6 Treatment in June is important only if late spring and early summer rains occur.
7 Make application at 1-5% hull split to manage hull rot caused by Rhizopus stolonifer.
ALMOND: TREATMENT TIMING
Note: Not all indicated timings may be necessary for disease control.
ALMOND: FUNGICIDE EFFICACY, CONTINUED
3 Field resistance of Alternariasp. and Cladosporium carpophilum to QoI and SDHI fungicides has been detected in almond orchards. AP-resistant
populations of Moniliniaspp. have been found on other stone fruit crops in California.
4 Of the materials listed, only sulfur, Abound, Gem, and some of the DMI fungicides (FRAC Group No. 3) are registered for use in late spring and early
summer when treatment is recommended.
5 PM-like refers to a powdery mildew-like disease on almond fruit that is managed with fungicides. Recent information suggests an Acremoniumspecies is
involved.
6 Excellent control obtained when combinations of Topsin-M or T-Methyl and Captan are used.
7 To reduce the risk of resistance development start treatments with a fungicide with a multi-site mode of action; rotate or mix fungicides with different mode
of action FRAC numbers for subsequent applications, use labeled rates (preferably the upper range), and limit the total number of applications/season.
8 Oils recommended include "light" summer oil, 1-2% volume/volume.
9 Not registered for use later than 5 weeks after petal fall.
10Effcacy reduced at high temperatures and relative humidity; experimental for Alternaria.
11Bravo Ultrex, Bravo WeatherStik, Echo Ultimate, and Chlorothalonil are currently registered.
12Do not use in combination with or shortly before or after oil treatment.
13Effcacy is better in concentrate (80-100 gal/acre) than in dilute sprays.
14The low rates necessary to avoid phytotoxicity in spring reduce the effcacy of copper.
15"Burns out" scab twig lesions when applied at delayed dormant. (Chlorothalonil can be applied with dormant oil during tree dormancy).
16Hull rot ratings are for the disease caused by Rhizopus stolonifer. Ratings for the disease caused by Moniliniaspp. will be provided in the future.
17Active ingredient, Trichoderma harzianum Rifai strain KRL-AG2, provides control of Silver leaf disease.