Artichoke, Ramularia Leaf Spot

Pathogen: Ramularia cynarae
 

SYMPTOMS

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)

A.        AZOXYSTROBIN

           (Quadris)        11 – 15.4 fl oz 4          0

           MODE OF ACTION: A Qol (Group 11)1
fungicide

           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 5          48

           MODE OF ACTION: A DMI (Group 3)1
triazole fungicide.

           COMMENTS: Check with your county
agricultural commissioner about the availability of this material under a Section
18 registration. Do not apply more than 0.4 lb a.i. acre/year or exceed 4
applications/year.

C.        BACILLUS
PUMILIS#

           (Sonata)          2–4 oz 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 R.E.I. exceeds the P.H.I. The longer of these two
intervals is the minimum time that must elapse before harvest.

*          

#          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. Fungicides with a different group
number are suitable to alternate in a resistance management program.