NATURAL ROOT GRAFTS IN RED PINE (PINUS RESINOSA AIT.)

The occurrence of root grafts in nine plantations which varied in age from 5-45 years was investigated. The spacing of the trees in all these plantations was approximately 6 feet by 6 feet at time of planting. The youngest plantation in which grafts between different trees were found was 15 years old. In all stands which were this age or older, grafting could be considered as a common occurrence. The majority of the grafts were found 4 to 14 inches below the soil surface. Although the number of sample pits was small, it appeared that the incidence of grafting was greater in thinned as opposed to unthinned stands of the same age. There was little evidence that numbers of grafts increased with age of stand. It was also concluded that when two roots graft, the root of smaller diameter and/or having the greater length between graft and tree receives a net increase in its food supply at the graft.