근년(近年) 우리나라의 과수생육(果樹生育)을 해(害)치는 Bark Necrosis의 원인(原因)을 구명(究明)하기 위한 엽(葉) 및 토양분석(土壤分析)의 결과(結果)는 다음과 같다. 망강은 본병유인(本病誘因)의 가장 중요(重要)한 인자(因子)의 하나이며 1962년(年) 필자(筆者)에 의(依)하여 얻어진 결과(結果)와 동일(同一)하다. 이병상(罹病狀)은 엽중(葉中) Mn 904 ppm에서 발생(發生)하였으며 평균(平均) 이병엽(罹病葉)의 Mn 함량(含量)은 건전엽(健全葉)(외관상(外觀上))의 4배(倍)이다. 이상(以上) 기술(記述)한 바와 같이 본(本) Bark necrosis는 Mn 과다흡수(過多吸收)에서오는 Mn-toxicity이며 Berg가 말한 "Internal Bark necrosis"이다. 본(本) Bark necrosis를 방지(防止)하기 위하여서는 토양(土壤) pH를 높이거나 혹은 다른 방법(方法)으로 과수(果樹)의 Mn 흡수(吸收)를 감소(減少) 시켜야 한다.
Leaf analysis was used as a means of diagnosis of unknown apple bark disease. The results obtained from analysis may be summarized as follow; Manganese is one of the most important element in the development of the bark disease. Evidence supporting this view was presented in 1962 by writers. Diseased symtom appears about 904 ppm of manganese and on average, manganese content of diseased leaves was 4 times as high as that of healty leaves. There is a significance between the reducible manganese in soil and the absorption of manganese in diseased leaves. Consequently, the disease should be considered manganese toxicity and may be the same one described by Berg as "Internal Bark Necrosis." In order to prevent the bark disease, plant absorption of manganese must be decreased with increasing soil pH, or by other means.
