배나무잎 이상반점증상의 접목전염 여부를 온실과 포장에서 여러 가지 접목방법으로 시험하였다. 이병가지와 건전가지를 2월에 채취하여 건전한 실생대목에 접목한 결과 이병가지를 접목한 가지에서만 발병되었다. 또한 이병가지와 건전가지를 각각 첫 번째 접수와 두 번째 접수로 하여 건전한 실생대목에 접목했을 때도 예외 없이 두 번째 접수에서의 발병이 확인되었다. 이병주와 건전주를 기부에 설접(舌接)하여도 두주 모두 발병하였다. 지표식물 HN-39를 두 번째 접수로 이용하고 첫 번째 접수를 이병가지로 하여 배나무 실생대목에 접목하면 HN-39에서 심하게 발병하였다. 농업과학기술원 과수원에서 건전주에 이병가지를 고접하면 고접 당년에는 접수에서만 발병되었고 다음 해에는 고접한 주지에, 3년차에는 배나무 전체가 심하게 발병하였다. 이상의 결과로 볼 때 배나무 이상반점 증상은 병원이 접목전염하는 것으로 생각된다.
Nature of graft transmissibility of pear abnormal leaf spot disease was examined by various grafting methods in the greenhouse and field. When the diseased and symptomless twigs were collected in winter and grafted in the next spring to the seed-originated healthy root stock, the abnormal leaf spot was developed only in the case of the diseased twigs. Double grafting on a seed-originated healthy root stock, where the diseased and the symptomless twigs were used as 1st and 2nd scions, respectively, developed abnormal leaf spot lesions without exception on the 2nd scions. Tongue-graft with the diseased and the symptomless trees also incited abnormal leaf spots on the both trees. Abnormal leaf spots were also developed on HN-39, an indicator pear tree, used as a 2nd scion in a double graft test, where the diseased twig and a seed-originated healthy tree were used as the 1st scion and the root stock, respectively. When the diseased twig was top-grafted to the healthy root stock, lesion development of abnormal spot was limited to the grafted twig itself in the 1st year, but expanded to the main branches in the 2nd year, and spread over the whole tree in the 3rd year. This result indicates that the causal agent of abnormal leaf spot disease is transmitted by graft.