How to Manage Pests

UC Pest Management Guidelines


Eutypa Dieback and Bot Canker

Pathogen: Eutypa lata, Botryosphaeria spp.

(Reviewed 10/14, updated 10/14)

In this Guideline:


Eutypa dieback, gummosis, and limb dieback, causes limbs or twigs to wilt and die suddenly in late spring or summer with the leaves still attached. The bark has a dark discoloration with amber-colored gumming; infected xylem tissue and cambium are discolored brown.


Disease organisms infect fresh pruning wounds in the fall and winter when pruning occurs during, or just before, rainfall. While new infections caused by Eutypa only occur during fall and winter rainfall, Botryospaeria species may infect during a spring or summer pruning followed by irrigation. It may also seem as if new infections have occured after spring pruning if this pruning did not remove all the previously infected wood.


Remove infected limbs at least 1 foot below any internal symptom of the disease. The preferred control method is to prune during July and August after harvest. There is less regrowth from pruning cuts if pruning is done in August. Ideally, pruning should be completed at least 6 weeks before the first fall rains. Treating wounds with paints or sealants has not been satisfactory due to the lack of long-term efficacy of these products or the difficulty in treating all pruning wounds immediately after they are made. If pruning wounds are made outside of the preferred pruning period of July through August, use a fungicide to treat the wounds.

Common name Amount per acre REI‡ PHI‡
(Example trade name)   (hours) (days)

Calculate impact of pesticide on air quality
Bee precaution pesticide ratings
When choosing a pesticide, consider its usefulness in an IPM program by reviewing the pesticide's properties, efficacy, application timing, and information relating to resistance management, honey bees, and environmental impact. Not all registered pesticides are listed. Always read the label of the product being used.
  (Topsin M WSB) 1.5 lb 2 days 1
  MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole carbamate (1)
  COMMENTS: Requires a Special Local Needs (section 24C) registration.
  (Rally 40WSP) 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 per season. Apply by tractor after pruning and before rainfall.
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 actions (for more information, see Fungicides with a different group number are suitable to alternate in a resistance management program. For fungicides with mode-of-action group numbers 1, 4, 9, 11, or 17, make no more than one application 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 fungicide with a different mode-of-action group number.



[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Apricot
UC ANR Publication 3433


J. E. Adaskaveg, Plant Pathology, UC Riverside
W. D. Gubler, Plant Pathology, UC Davis
W. W. Coates, UC Cooperative Extension, San Benito County
J. J. Stapleton, UC IPM Program, Kearney Agricultural Center, Parlier
J. L. Caprile, UC Cooperative Extension, Contra Costa County
B. A. Holtz, UC Cooperative Extension, Madera County
K. M. Kelley Anderson, UC Cooperative Extension, Stanislaus County

Acknowledgment for contributions to Diseases:
B. L. Teviotdale, Kearney Agricultural Center, Parlier

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