Agriculture: Almond Pest Management Guidelines

Green Fruit Rot (Jacket Rot)

Symptoms and Signs

Green fruit rot begins during the latter part of the bloom period when the fungus infects senescing petals and anthers. Infected petals develop water-soaked brown spots. Some infected petals may fall onto leaves causing secondary infections. Anther infections can spread to floral tubes or flower jackets causing them to wither and stick to developing fruit. As fruit sets and starts to grow, a brown spot develops where the jacket sticks to it. This is particularly a problem where nut clusters trap senescing flower parts. Frequently this leads to rot of entire nut clusters.

Comments on the Disease

This disease is of little importance in many years, but when conditions are cool and wet during bloom, it can cause severe losses. One or more of several pathogens may be involved.

Management

When bloom is extended and moisture is abundant, apply a fungicide at full bloom to prevent green fruit rot. Continue treatment until rain stops. Be sure the fungicide you choose is effective against all three potential pathogens; demethylation (sterol) inhibitor fungicides such as myclobutanil (Laredo) and propiconazole (Orbit) are not effective against Botrytis cinerea.

Common name Amount per acre REI‡ PHI‡
(Example trade name) (hours) (days)
Not all registered pesticides are listed. The following are ranked with the pesticides having the greatest IPM value listed first—the most effective and least likely to cause resistance are at the top of the table. When choosing a pesticide, consider information relating to the pesticide's properties and application timing, honey bees, and environmental impact. Always read the label of the product being used.
A. DIFENOCONAZOLE/CYPRODINIL
(Inspire Super) 10.0-12.0 fl oz 12 60
MODE-OF-ACTION GROUP NAME (NUMBER1): demethylation (sterol) inhibitor (3) and anilinopyrimidine (9)
COMMENTS: Do not make more than two successive applications, and no more than four per season, to limit the development of resistance.
B. FLUOPYRAM/TRIFLOXYSTROBIN
(Luna Sensation) 5.0-7.6 fl oz 12 14
MODE-OF-ACTION GROUP NAME (NUMBER1): succinate dehydrogenase inhibitor (7) and Quinone outside inhibitor (11)
COMMENTS: Do not make more than two successive applications, and no more than four per season, to limit the development of resistance.
C. PYRACLOSTROBIN/BOSCALID
(Pristine) 10.5–14.5 oz 12 25
MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and succinate dehydrogenase inhibitor (7)
COMMENTS: Do not make more than four applications per season of QoIs or SDHIs and no more than two sequential applications before rotation to a different mode of action fungicide to limit the potential for the development of resistance.
D. IPRODIONE
(Rovral, Nevado) 1 pt 24 See comments
MODE-OF-ACTION GROUP NAME (NUMBER1): Dicarboximide (2)
COMMENTS: Do not apply later than 5 weeks after petal fall. 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.
E. PYRIMETHANIL
(Scala SC) 9–18 fl oz 12 30
MODE-OF-ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9)
F. THIOPHANATE-METHYL
(Topsin M 70WSB) 1.5 lb 72 (3 days) See label
MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1)
COMMENTS: 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 per acre.
G. CYPRODINIL
(Vangard WG) 5 oz 12 60
MODE-OF-ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9)
COMMENTS: Do not apply more than 30 oz/acre per crop per year.
H. FENHEXAMID
(Elevate) 1.5 lb 12 See comments
MODE-OF-ACTION GROUP NAME (NUMBER1): Hydroxyanilide (17)
COMMENTS: Apply up to 28 days after petal fall.
I. CAPTAN
(various 50WP) Label rates See label See label
MODE-OF-ACTION GROUP NAME (NUMBER1): Multi-site contact (M4)
COMMENTS: Do not apply in combination with, immediately before, or closely following oil sprays.
J. PYRACLOSTROBIN/FLUXAPYROXAD
(Merivon) 6.5 oz 12 14
MODE-OF-ACTION GROUP NAME (NUMBER1): quinone outside inhibitor (11) and succinate dehydrogenase inhibitor (7)
COMMENTS: Do not make more than two successive applications, and no more than three applications per season or 19.5 fl oz/acre per season, to limit the development of resistance.
K. POLYOXIN D ZINC SALT
(Ph-D) 6.2 oz 4 0
MODE-OF-ACTION GROUP NAME (NUMBER1): glucan synthesis (19)
COMMENTS: Do not make more than three applications per season and no more than two sequential applications before rotation to a different mode of action fungicide.
Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (PHI) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of these two intervals is the minimum time that must elapse before harvest may occur.
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with a different group number are suitable to alternate in a resistance management program. In California, make no more than one application of fungicides with mode-of-action group numbers 1, 4, 9, 11, or 17 before rotating to a fungicide with a different mode-of-action group number; for fungicides with other group numbers, make no more than two consecutive applications before rotating to a fungicide with a different mode-of-action group number.
QoI = quinone outside inhibitor or strobilurin
SDHI = succinate dehydrogenase inhibitor
Text Updated: 08/17
Treatment Table Updated: 08/17