How to Manage Pests

UC Pest Management Guidelines

Grape

Bot Canker

Pathogen: Botryoshaeria spp.

(Reviewed 6/06, updated 4/14)

In this Guideline:


Symptoms

Bot canker causes death of arms, cordons, and vines. The wedge-shaped, darkened cankers that develop in the woody vascular tissue are indistinguishable from Eutypa dieback. Unlike Eutypa dieback, there are no foliar symptoms.

Comments on the Disease

Bot canker is a pruning wound disease commonly seen in vines 10 or more years old. Pycnidia, spore-producing structures produced on surface of canker, provides inoculum for infection. Bot canker is the major cause of arm and cordon death statewide and is most prevalent south of Madera County.

Management

If your table grape vineyard has a history of Bot canker, look for symptoms of poor budbreak in spring and for damage symptoms in late summer or fall.

Pruning wounds provide an infection site. Once infected, complete removal of canker is necessary. On older vines, doubling of spurs to replace lost spur positions and extensive cordon retraining is necessary to maintain production. Cultural practices, such as proper water and fertilizer management and good pruning techniques, designed to maintain vine vigor are necessary and may enable the vines to outgrow infections by this organism.

Common name Amount per acre** R.E.I.‡ P.H.I.‡
(example trade name)   (hours) (days)

  Calculate impact of pesticide on air quality
When choosing a pesticide, consider efficacy and the general properties of the fungicide as well as information relating to environmental impact.
 
A. THIOPHANATE-METHYL
  (Topsin-M WSB) See label 48
  MODE-OF-ACTION GROUP NAME (NUMBER1): Methyl benzimidazole carbamates (B1)
  COMMENTS: Can be applied as a paint or spray application. Use allowed under a Special Local Needs label.
 
B. MYCLOBUTANIL
  (Rally 40WSP) 4–5 oz 24 14
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (G1)
  COMMENTS: Use allowed under a Special Local Needs label.
 
C. TETRACONAZOLE
  (Mettle 125ME) 3–5 oz 12 14
  MODE-OF-ACTION GROUP NAME (NUMBER1): Demethylation inhibitor (G1)
  COMMENTS: Do not apply more than 10 fl oz/acre per season.
 
** Apply with enough water to provide complete coverage.
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 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. Fungicides with a different Group number are suitable to alternate in a resistance management program. For more information, see http://www.frac.info/.
NA Not applicable.

PUBLICATION

[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Grape
UC ANR Publication 3448

Diseases

W. D. Gubler, Plant Pathology, UC Davis
R. J. Smith, UC Cooperative Extension, Sonoma County
L. G. Varela, UC IPM Program, Sonoma County
S. Vasquez, UC Cooperative Extension, Fresno County
J. J. Stapleton, UC IPM Program, Kearney Agricultural Research Center, Parlier
A. H. Purcell, Environmental Science, Policy and Management, UC Berkeley
Acknowledgment for contributions to Diseases:
G. M. Leavitt, UC Cooperative Extension, Madera County

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