Blackheart Injury in ‘Starkspur Supreme Delicious’ on Nine Rootstocks in the 1980-1981 NC-140 Cooperative Planting

Abstract

Blackheart was measured at 25 cm above the soil surface in trees in the NC-140 ‘Starkspur Supreme Delicious’ plantings located in Iowa, Ohio, Quebec, Tennessee, and Virginia after at least ten years of growth. Trees at all five locations exhibited blackheart injury. However, trees grown in Iowa, under the coldest climatic conditions, had the greatest amount of blackheart. Trees grown in Ohio and Quebec were intermediate in blackheart injury, while those grown in Tennessee and Virginia, under mild winter conditions, had less injury. Overall, M.7 EMLA and OAR.l trees had greater blackheart injury than M.9 and Ottawa 3 (O.3) trees. All MAC.24 trees were killed in Iowa in 1986 due to a November freeze and all M.27 EMLA trees in Ohio were dead by the spring of 1989 due to severe frost heaving conditions.