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UC Pest Management Guidelines


Ramularia leaf spot lesions on artichoke leaf.

Artichoke

Ramularia Leaf Spot

Pathogen: Ramularia cynarae

(Reviewed 1/07, updated 6/09)

In this Guideline:


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/Acre R.E.I.+ P.H.I.+
(trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
 
A. AZOXYSTROBIN
  (Quadris) 11 – 15.4 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/crop year. Do not apply more than 2.88 pts (1.5 lb a.i.)/acre/crop year. Also controls powdery mildew and Botrytis.
 
B. MYCLOBUTANIL
  (Rally) 40WSP 2–4 oz 24 3
  MODE OF ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (3)
  COMMENTS: Do not apply more than 0.4 lb a.i. acre/year or exceed 4 applications/year.
 
C. BACILLUS PUMILIS#
  (Sonata) 2–4 qt 4 0
  MODE OF ACTION: A biological fungicide.
  COMMENTS: Apply at 7– to 14– day intervals. Can be used in rotation with azoxystrobin or myclobutanil for resistance management in nonorganic fields.
 
+ Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) 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.
* Permit required from county agricultural commissioner for purchase or use.
# Acceptable for use on organically grown produce.
1 Group numbers are assigned by the Fungicide Resistance Action Committee (FRAC) according to different modes of actions (for more information, see http://www.frac.info/). 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.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Artichoke
UC ANR Publication 3434
Diseases
S. T. Koike, UC Cooperative Extension, Monterey County
Acknowledgment for contributions to Diseases:
S. Colbert, Griffin Corp., Valdosta, GA

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