How to Manage Pests

UC Pest Management Guidelines

SYMPTOMS

Cladosporium leaf spot is characterized by round, tan leaf spots that rarely exceed 0.25 inch in diameter. Dark green spores and mycelium later develop in the centers of these spots. The presence of dark green sporulation distinguishes Cladosporium leaf spot from anthracnose and Stemphylium leaf spot diseases, both of which also form circular lesions.

COMMENTS ON THE DISEASE

Cladosporium leaf spot occurs to some extent almost every year. However, the disease is rarely severe unless there are significant rains in spring. Weed or other reservoir hosts have not been identified. This pathogen is seedborne.

MANAGEMENT

Treatment is rarely necessary. If used, copper sprays must be applied as protectants.

Common Name		Amount/Acre	R.E.I. +	P.H.I.+
(trade name)			(hours)	(days)
When choosing a pesticide, consider information relating to environmental impact. Not all registered pesticides are listed. Always read label of product being used.
A.	COPPER HYDROXIDE	Label rates	24	0
	MODE OF ACTION GROUP NAME (NUMBER1): Multi-site contact (M1)
	COMMENTS: Copper sprays are not very effective. Apply as a protectant spray at 10–14 day intervals. Rate often depends upon disease severity. A suitable agricultural spray oil is recommended for use with some copper formulations. Consult label for specific application guidelines.
+	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.
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.

PUBLICATION

UC IPM Pest Management Guidelines: Spinach
UC ANR Publication 3467
Diseases
M. LeStrange, UC Cooperative Extension, Tulare County
S. T. Koike, UC Cooperative Extension, Monterey County
Acknowledgements for contributions to Diseases:
F. F. Laemmlen, UC Cooperative Extension, Santa Barbara County

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