Post-budbreak freeze events on 7–8 Apr 2007 were followed by the development of aerial roots on winegrapes later in the spring and continuing through the summer months. Rainfall and relative humidity were much higher than average during the months of May, June, and July following the freeze events. Aerial rooting of grapes has not been previously reported in Oklahoma; therefore, quantitative counts of aerial rooting were performed to determine if there was a relationship between aerial root formation and subsequent vine productivity. Aerial root production varied by scion cultivar and the effect of rootstock was unclear. Only Petit Verdot produced significantly more roots on a rootstock than not. It appears that the formation of aerial roots on grapevines in situ is a complex interaction of freeze injury and subsequent environmental conditions to produce roots. Aerial rooting was likely a sign of injury, but the number of aerial roots produced did not necessarily represent the degree of injury. Few or no roots may be produced when injury or damage is slight, more with moderate injury or damage, and few again when significant injury or damage is sustained.
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