The effect of crown gall on growth of cherry trees

Abstract

Over 1000 cherry trees, as rootstocks, nursery sweet cherry or ornamental cultivars or orchard trees up to 7 years old, with or without galls, were examined to determine the effect, if any, of crown gall disease on tree growth. No clear, consistent differences between healthy and galled trees were found. Healthy 1‐year‐old F12/ 1 rootstocks were smaller than their galled counterparts but the reverse was true for 2‐year‐old sweet cherries and ornamental cultivars. The mean girth of non‐galled 6‐year‐old trees of cv Schrecken was greater than that of galled trees from the same orchard. Detailed records on two sweet cherry cultivars, Napoleon and Roundel, revealed some differences in growth rate in the early years between healthy trees and those with various levels of galling at planting, but these differences were not sustained. Irrespective of gall status at planting no correlation was detected between final gall status and ultimate tree size. The data support the view that there is no consistent effect of crown gall on cherry tree growth and that the adverse appearance of affected nursery material is the main problem with this disease.