EIGHTEEN YEARS' RESULTS WITH DWARF INTERSTOCKS M.9 AND B.9 ON GROWTH AND CROPPING OF TWO APPLE CULTIVARS

The data obtained over 18 years showed that, in general, trees on M.9 or B.9 rootstocks or interstocks were 51–81% smaller than those grafted directly on Antonovka seedlings. Trees with a B.9 interstock were 37–50% smaller than those grafted directly on M.7.

Trees with B.9 or M.9 rootstocks or interstocks produced larger and better-coloured fruits especially as they became older. They produced 28% more apples of over 70 mm diameter than did trees on Antonovka seedlings, M.7 and MM.106 and 62% more apples which had 25% or more of their surface with a red blush than did trees on Antonovka seedlings.

The interstock trees were much more liable to produce root suckers than trees on M.9 or B.9 rootstocks.

During the 18 years of the trial about 43% of the trees on M.9 and B.9 rootstocks were lost, mainly because of poor anchorage, while only 12% of those with M.9 and B.9 interstocks were lost, mainly because of rodent damage.

Trees with B.9 interstocks on Antonovka seedling rootstocks are therefore recommended for Polish conditions. They are very well adapted to light podsolic soils.

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