The seasonal release of spores of Nectria galligena from apple cankers in Northern Ireland

SUMMARY Trapping of ascospores and conidia of Nectria galligena Bres. released from cankers on Bramley's Seedling apple trees over a period of three years showed that ascospores were most prevalent in the spring and early summer, and conidia from early summer to late autumn. Few ascospores were released in late summer or mid‐winter but a minor period of discharge occurred in autumn. The distribution of cankers within trees in various orchards was also examined, and most were found to occur at the junctions of different seasons' growth. Possible reasons for this are discussed.