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How to Manage Pests

UC Pest Management Guidelines


Crown gall on the crown and roots of a young tree.

Peach

Crown Gall

Pathogen: Agrobacterium tumefaciens

(Reviewed 4/10, updated 4/10)

In this Guideline:


SYMPTOMS AND SIGNS

Crown gall appears as rough, abnormal galls on roots or trunk. Galls are soft and spongy. The center of older galls decay. Young trees become stunted; older trees often develop secondary wood rots.

COMMENTS ON THE DISEASE

The bacteria survive in gall tissue and in soil. Crown gall is most damaging to young trees, either in the nursery or new orchard plantings. All peach rootstocks are susceptible to crown gall.

MANAGEMENT

The incidence of crown gall can be reduced by planting noninfected, "clean" trees. It is also important to carefully handle trees to avoid injury as much as possible, both at planting and during the life of the tree in the orchard. Preplant, preventive dips or sprays with a biological control agent are available and may be helpful in some orchards. Generally, by the time crown gall is evident in a peach orchard, it is usually best to tolerate the problem for the few remaining years of orchard life or just remove the orchard and start anew.

When replanting a previously affected site, remove as many of the old tree roots as possible, grow a grass rotation crop to help degrade leftover host material and reduce pathogen levels, and offset the new trees from the previous tree spacing to minimize contact of healthy new roots with any infested roots that may remain.

Common name Amount to Use 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. AGROBACTERIUM TUMEFACIENS-84#
  (Galltrol) Label rates 12 0
  COMMENTS: Preventive preplant treatment only.
 
B. GALLEX Label rates 0 0
  COMMENTS: For removal of existing galls, apply winter through spring.
 
# Acceptable for use on organically grown produce.
+ 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.

[Precautions]

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Peach
UC ANR Publication 3454
Diseases
J. E. Adaskaveg, Plant Pathology, UC Riverside
R. A. Duncan, UC Cooperative Extension Stanislaus County
J. K. Hasey, UC Cooperative Extension Sutter/Yuba counties
K. R. Day, UC Cooperative Extension Tulare County
Acknowledgment for contributions to Diseases:
W. D. Gubler, Plant Pathology, UC Davis
B. L. Teviotdale, Kearney Agricultural Center, Parlier

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