Studies on the dissemination of peach anthrachnose.

III. Histopathological observation.

Abstract

In the present paper are given the results of histopathological observations on the infection of peach by Gloeosporium laeticolor. As previouly reported (4), the anthracnose fungus first attacks the trichomes of young fruits. The infection hyphae penetrate into the trichome cells and the mycelium passes into the epidermal cells of young fruits (Fig 2). The mycelium grows very rapidly in the young fruit tissue and usually runs out from the dead tissue (Fig 3). The fungus then invades into the twig through the peduncle without causing fruit-drop.
Isolations from the serial cut-pieces of the affected twigs demonstrated that in late spring the coloniation by the fungus was restricted to the vicinity of the point of attachment of the diseased young fruit, but the mycelium spread gradually until December to permeate through the infected twig. The affected twig, however, remained alive as late as the next April (Fig 6).
The fungus can penetrate a young shoot besides trichomes of a fruit. Under natural conditions, however, the shoot grow too old to be infected when the conidia are disseminated. Therefore, it is concluded that the young fruit is practically the sole entry port of the peach anthracnose fungus.