Primary Investigation of Relationship Between Tree-age or Light Intensity and Leaf Scorch Disease of Platanus Acerifolia(Ait.) Wild.and Its Occurrence Growth and Decline Trend

Platanus acerifolia(Ait.)Wild leaf scorch disease occurrence trend and environmental light intensity or age of tree impact on it were investigated in 2008.The result showed that Platanus acerifolia(Ait.)Wild leaf scorch disease started occurring at mid-May,the disease developed slowly during later-May to mid-July and progressed faster from later-July,Platanus acerifolia(Ait.)Wild leaf scorch disease spread evidently bad during August to later-October.Environmental light intensity had influenced heavily to the disease indices.The diseased indices at the sun(41.66%)were evidently higher than that of at sunless(13.77%).Diseased tree percentage had evidently difference to different tree's age,the disease indices at sunless had not evidently difference.The disease indices had increased with increment of tree-age at the sun.