The gumming of Phillips Cling peaches

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Introduction

The production of gum by stone fruits and stone-fruit trees is rather common. The gumming appears most often on the branches or trunks and is associated with injury from an organism, an insect, or a mechanical source. Gumming on the fruit is less common than that on the tree, and gumming restricted to certain varieties occurs even less frequently. The Phillips Cling, a leading canning peach, suffers from gumming of the last-mentioned class; and since about 1927 the losses from this cause have constituted a major problem of the growers of this variety. This paper deals with the description and case history of the disease, together with experiments in its control.

Types of Gumming

At least four different types of gumming occur on the Phillips Cling.⁽²⁾3 All types of gum exuding from the fruit seem to have one common characteristic: they are all clear and colorless. Stone⁽⁷⁾ has described a gum of similar appearance occurring on peaches.

Gumming from External Injury.—The peach, in common with most other stone fruits, will gum when subjected to an external injury such as an insect puncture, limb or leaf rub, or Coryneum (shot-hole) infection. A wide variety of gumming from one or more of these causes may be found on the Phillips Cling. The gum does not occur at any particular place on the periphery of the fruit and may appear at any time before the yellow undercolor begins to develop prior to harvest.