Symptoms and Signs
Ramularia leaf spot is characterized by circular, brown lesions on both upper and lower surfaces of leaves. If disease is severe, lesions will coalesce and the entire leaf will turn brown and dry up. White spores of the fungus will usually develop in leaf lesions. On flower bracts, brown patchy lesions will also form, causing the bracts to curl and dry out.
Comments on the Disease
Infections on flower bracts usually make the artichoke bud unmarketable.
Management
Consider a fungicide application when flower bract infection follows leaf infection.
| 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) | 20 fl oz | 12 | 3 | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)/anilino-pyrimidine (9) | ||||
| B. | AZOXYSTROBIN/DIFENOCONAZOLE | |||
| (Quadris Top) | 10–14 fl oz | 12 | 3 | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11)/demethylation inhibitor (3) | ||||
| C. | FLUOPYRAM/TRIFLOXYSTROBIN | |||
| (Luna Sensation) | 7.6 fl oz | 12 | 0 | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Succinate-dehydrogenase inhibitor (7)/quinone outside inhibitor (11) | ||||
| D. | TRIFLOXYSTROBIN | |||
| (Gem 500 SC, Flint Extra) | 3.0–3.8 fl oz | 12 | 0 | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) | ||||
| E. | AZOXYSTROBIN | |||
| (Quadris) | 11–15.5 fl oz | 4 | 0 | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Quinone outside inhibitor (11) | ||||
| COMMENTS: Do not apply more than one application before alternating with a fungicide that has a different mode-of-action group number. Do not make more than 4 applications/acre per crop year. Do not apply more than 2.88 pts (1.5 lb a.i.)/acre per crop year. Also controls powdery mildew and Botrytis. | ||||
| F. | MYCLOBUTANIL | |||
| (Rally 40WSP) | 4 oz | 24 | 3 | |
| MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3) | ||||
| COMMENTS: Do not apply more than 0.4 lb a.i./acre per year or exceed 4 applications per year. | ||||
| ‡ | 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 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. |