Author
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Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/21/2007 Publication Date: 11/1/2004 Citation: Baumgartner, K. 2004. Root collar excavation for postinfection control of Armillaria root disease of grapevine. Plant Disease. 88: 1235-1240. Interpretive Summary: Root collar excavation for control of Armillaria root disease of grapevine was investigated in two California vineyards. This technique involves permanent removal of soil from the base of infected grapevines, in an attempt to protect this important part of the grapevine root system. The hypothesis tested was that root collar excavation, when timed in early stages of Armillaria root disease, may cause the pathogen, Armillaria mellea, to recede from the root collar before damage to water conductive tissue occurs. Root collar excavations were done on 50 healthy and 50 symptomatic grapevines per vineyard. Nonexcavated control grapevines (50 healthy, 50 symptomatic) were included for comparison. In vineyard N1, root collar excavation significantly increased yield and cluster weights of symptomatic grapevines. Symptomatic, excavated grapevines in vineyard N1 had the same high cluster weights as healthy grapevines and there were no significant effects of excavation on yields or pruning weights of healthy grapevines. In vineyard K1, excavation had no effect on yields or pruning weights of symptomatic grapevines and had significant negative effects on pruning weight and shoot weight of healthy grapevines. After root collars of all grapevines were re-examined, A. mellea was found to be absent from the root collars of symptomatic, excavated grapevines. Root collar excavation appears to be promising for Armillaria root disease, as long as excavated root collars are kept clear of soil, in that it is extremely inexpensive and it improves yields of moderately symptomatic grapevines. Technical Abstract: Root collar excavation for control of Armillaria root disease of grapevine was investigated in two California vineyards. The hypothesis tested was that root collar excavation, when timed in early stages of root collar infection, may cause mycelial fans of the pathogen, Armillaria mellea, to recede from the root collar before xylem decay occurs. In August 2002, soil was removed to expose root collars of 50 healthy and 50 symptomatic grapevines per vineyard. Nonexcavated grapevines (50 healthy, 50 symptomatic) were randomly sampled in each vineyard, giving a total of four experimental treatments. In October 2002 and 2003, yields of 30 grapevines per treatment were measured in each vineyard. In March 2004, pruning weights were measured from the same grapevines. Symptomatic grapevines had significantly fewer clusters, lower yields, lower cluster weights, fewer shoots, lower pruning weights, and smaller shoots than healthy grapevines in both vineyards. In vineyard N1, excavation significantly increased yield and cluster weights of symptomatic grapevines. Symptomatic, excavated grapevines in vineyard N1 had the same high cluster weights as healthy grapevines and there were no significant effects of excavation on yields or pruning weights of healthy grapevines. In vineyard K1, excavation had no effect on yields or pruning weights of symptomatic grapevines and had significant negative effects on pruning weight and shoot weight of healthy grapevines, compared to that of healthy, nonexcavated grapevines. After root collars of all grapevines were re-examined, mycelial fans were absent from the root collars of symptomatic, excavated grapevines. Root collar excavation appears to be promising for Armillaria root disease, as long as excavated root collars are kept clear of soil, in that it is extremely inexpensive and it improves yields of moderately symptomatic grapevines. |
