Replant Disease Complex1
Woolly Apple Aphid2
Burr Knot Formation3
S = Susceptible T = Tolerant (moderately resistant under ideal conditions). R = Resistant VR = Very resistant
— = Indicates information is not available.
1Replant disease complex consists of several pathogens (Cylindrocarpon, Pythium spp., Fusarium and Rhizoctonia), bacteria and parasitic nematodes 2Does not effectively control high pressure from aerial colonies of woolly apple aphid. 3Burr knots are common entry points for insect pests such as dogwood borer. 4Though moderately resistant to Phytophthora, M.26 will not perform well on poorly-drained sites. 5This rootstock is considered only moderately tolerant to replant disease and does not perform as well against this disease as other Geneva series rootstocks in moderate- to high-pressure conditions.
Adapted from 2020-2021 Penn State Tree Fruit Production Guide, Geneva Apple Rootstocks Comparison Chart v.4 (https://ctl.cornell.edu/wp-content/uploads/plants/GENEVA-Apple-Rootstocks-Comparison-Chart.pdf) and Wilson, K. (2000). Apple Rootstocks. Ontario Ministry of Agriculture, Food & Rural Affairs, Factsheet 00-007.