Symptoms and Signs
Fruit in storage infected with Monilinia fructicola may develop visible decay within 24 hours at 72°F, and will produce spores in 30 hours. Decaying tissue changes from light brown to gray to black. Rotted tissue is firm and difficult to distinguish from healthy tissue.
Rhizopus stolonifer causes fruit to turn mushy and leaky in storage containers. The disease spreads rapidly from fruit to fruit. Infected tissue can be readily distinguished from healthy tissue.
Comments on the Disease
Monilinia is the most common fruit decay organism. Fruit that has been injured and infected before storage provides the inoculum for the spread of Monilinia. Rhizopus produces many spores at low humidity, but in fruit packages, where humidity is high, spores are scarce and mycelia abundant.
Management
Fungicides are preventive, not eradicative; they must be applied to uninjured fruit before infections occur. Injured fruit cannot be protected from rot caused by Monilinia or Botrytis with the use of preharvest sprays. After harvest, Rhizopus can be controlled by storing the crop at temperatures below 40°F. Preharvest sprays for Monilinia should be applied as needed during the last 4 weeks before harvest. Where Rhizopus fruit rot is a problem, treat 10 days to 1 day before harvest.
Take a fruit sample at harvest to assess the effectiveness of current year's IPM program and to determine needs for next year's program. See FRUIT EVALUATION AT HARVEST and record your results on a monitoring form .
| Common name | Amount to use | 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. | ||||
| PREHARVEST | ||||
| A. | PROPICONAZOLE | |||
| (Orbit) 3.6 EC | 4 fl oz/acre | 24 | 0 | |
| (Bumper) 41.8 EC | 4 fl oz/acre | 24 | 0 | |
| MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) | ||||
| COMMENTS: Most effective when applied before a rainfall and allowed to dry. Do not apply to "Stanley" type plums. Maximum of 2 preharvest sprays. | ||||
| B. | PYRIMETHANIL | |||
| (Scala) SC | 18 fl oz | 12 | 2 | |
| MODE OF ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9) | ||||
| COMMENTS: Do not apply more than 2 applications of Group 9 fungicides within 30 days of harvest. | ||||
| C. | CYPRODINIL | |||
| (Vangard) WG | 10 oz | 12 | 2 | |
| MODE OF ACTION GROUP NAME (NUMBER1): Anilinopyrimidine (9) | ||||
| COMMENTS: High summer temperatures and relative humidity reduces efficacy. Apply a maximum of 2 applications during preharvest. Do not apply more than 20 oz/acre/year. | ||||
| D. | PYRACLOSTROBIN/BOSCALID | |||
| (Pristine) | 10.5–14.5 oz/acre | 12 | 0 | |
| MODE OF ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) and Carboxamide (7) | ||||
| E. | MYCLOBUTANIL | |||
| (Rally) 40W | 2.5–6 oz | 24 | 0 | |
| MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) | ||||
| COMMENTS: Do not apply more than 2.75 lb/acre/season. | ||||
| POSTHARVEST | ||||
| A. | FLUDIOXONIL | |||
| (Scholar) 50WP | 8 oz/100 gal water | 0 | 0 | |
| MODE OF ACTION GROUP NAME (NUMBER1): Phenylpyrrole (12) | ||||
| COMMENTS: Treats 200,000 lb fruit using a spray-application system. | ||||
| B. | THIOPHANATE METHYL | |||
| (Topsin-M) 70W | 8 oz/100 gal water | 12 | 1 | |
| MODE OF ACTION GROUP NAME (NUMBER1): Methyl benzimidazole (1) | ||||
| COMMENT: Sporadic control may occur if fruit treated is infected with spores of benzimidazole-resistant strains of Monilinia spp. If resistance has occurred in your orchard, do not use this 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 two intervals is the minimum time that must elapse before harvest. |
| 1 | Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of action. Fungicides with different group numbers are suitable to alternate in a resistance management program. In California, make no more than one application of a fungicide with a mode-of-action group number associated with high resistance risk before rotating to a fungicide with a different mode-of-action group number; for other fungicides, make no more than two consecutive applications before rotating to fungicide with a different mode-of-action group number. |