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Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only Publication Acceptance Date: 4/1/2004 Publication Date: 8/1/2004 Citation: Baumgartner, K. 2004. Cultural control of armillaria root disease of grape. American Phytopathological Society Annual Meeting. Interpretive Summary: A technique known as root collar excavation was investigated for control of Armillaria root disease of grapevines. The technique involves permanent removal of soil from the base of a grapevine (the root collar) to a depth of approximately 1 ft. When timed in early stages of root collar infection, root collar excavation may cause the fungus that causes Armillaria root disease, Armillaria mellea, to recede from the root collar before it causes irreparable damage. In 2002, root collars of healthy and symptomatic grapevines were excavated in two California vineyards (vineyard K1, vineyard N1). In 2002 and 2003, yields of excavated grapevines were measured and compared to yields of nonexcavated grapevines. In 2004, pruning weights were measured from the same vines. Symptomatic vines had significantly fewer clusters, lower yields, smaller clusters, fewer shoots, lower pruning weights, and smaller shoots than healthy grapevines in both vineyards. In vineyard N1, excavation improved yield and cluster weight of symptomatic grapevines. In fact, symptomatic-excavated grapevines in vineyard N1 had the same high cluster weights as healthy grapevines. In vineyard K1, excavation did not improve yield or cluster weight of symptomatic grapevines, but instead decreased pruning weight of healthy vines. Differences between the vineyards are likely due to frequent re-filling of excavated root collars in vineyard K1, where root collar excavation was ineffective. Technical Abstract: Root collar excavation for control of Armillaria root disease of grape was investigated in two California vineyards (vineyard K1, vineyard N1) from 2002 to 2004. When timed in early stages of root collar infection, root collar excavation may cause mycelial fans of Armillaria mellea to recede from the root collar before xylem is decayed. In 2002, soil was removed to expose root collars of 50 healthy and 50 symptomatic vines/vineyard. Nonexcavated vines (50 healthy, 50 symptomatic) were randomly chosen, for a total of four treatments. In 2002 and 2003, yields of 30 vines/treatment/vineyard were measured. In 2004, pruning weights were measured from the same vines. Symptomatic vines had significantly fewer clusters (P<0.0001), lower yields (P<0.0001), lower cluster weights (P<0.0001), fewer shoots (P<0.0001), lower pruning weights (P<0.0001), and smaller shoots (P<0.0001) than healthy vines in both vineyards. In vineyard N1, excavation had a significant positive effect on yield (P=0.0231) and cluster weight (P=0.0042) of symptomatic vines, compared to symptomatic, nonexcavated vines. Symptomatic, excavated vines in vineyard N1 had the same high cluster weights as healthy vines and there were no significant effects of excavation on yields or pruning weights of healthy vines. In vineyard K1, excavation had no effect on yields or pruning weights of symptomatic vines and had significant negative effects on pruning weight (P=0.0008) and shoot weight (P=0.0373) of healthy vines, compared to healthy, nonexcavated vines. Differences between the vineyards are likely due to frequent re-filling of excavated root collars in vineyard K1, where root collar excavation was ineffective. |
