Brownline Disease or Constriction Disease of Stanley PruneI. Introduction: This disease is a problem on 'Stanley' prune propagated on certain selections of myrobalan rootstock. It is caused by tomato ringspot virus, the causal agent of Prunus stem pitting.
II. Symptoms: With virus infection, a dark brown line forms at the graft union and extends into pits and grooves in the woody tissue. This girdling causes interveinal chlorosis of the leaves of the scion, and the tree dies. Trees with constriction disease exhibit smaller than normal pale green to yellow leaves and reduced tree growth. Affected trees decline for one to three years before death occurs. Declining trees often sucker heavily from the myrobalan rootstock. When soil is removed from around the base of an infected tree, the shank of the myrobalan rootstock often appears restricted on one side and smaller in diameter than the 'Stanley' prune trunk immediately above the union. Marianna 2624 plum rootstocks appear to be resistant to virus infection, displaying none of the symptoms of constriction disease. This is the only source of resistance currently available for tomato ringspot virus in Prunus for use with compatible plum scion material.
III. Monitoring: Be aware of the symptoms of this disease. No routine monitoring is required.
V. Management: Purchase certified virus-free trees. Cultivating the site for 2 years is recommended if trees are to be re-established on infested sites.
Text prepared by E.V. Podleckis and R. Welliver
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