File:The encyclopedia of practical horticulture; a reference system of commercial horticulture, covering the practical and scientific phases of horticulture, with special reference to fruits and (20185255023).jpg

Title: The encyclopedia of practical horticulture; a reference system of commercial horticulture, covering the practical and scientific phases of horticulture, with special reference to fruits and vegetables;
Identifier: CUbiodiversity628875-9365 (find matches)
Year: 1914 (1910s)
Authors: Lowther, Granville, ed; Worthington, William, 1871-
Subjects: Gardening; Fruit-culture; Vegetable gardening
Publisher: North Yakima, Wash. , The Encyclopedia of Horticulture Corporation
Contributing Library: Cornell University Library
Digitizing Sponsor: Mann Library, Cornell

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1624 ENCYCLOPEDIA OF PRACTICAL HORTICULTURE
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Bartlett Pear Tree Showiu^- the Blight Eradi- cated from the Body. It was necessary to cut part of the root system away. This tree is capable of bearing a normal crop. (Orig- inal.) prove that insects* cause some of the in- fections of some of the twigs, it is not absolutely certain that they do all the inoculating. Twigs are sometimes found with blight started in the axils of the leaves or in the tender bark where no punctures can be found on careful exam- ination. It is possible that the germ may enter in damp weather through growth cracks where the cuticle is ruptured, ex- posing the tender tissues. Means of Infection That insects really carry pear-blight germs on their feet and mouth parts, I have proved by capturing these insects in infected orchards and allowing them to walk about on prepared culture plates known as Petri dishes, which contained a substance in which germs might make growth. In from 24 to 48 hours colonies of germs would be found growing from the points where the insects walked upon the culture medium. By inoculating growing shoots from these cultures, typi- ' cal cases of blight were produced. Numerous experiments have been made by atomizing the germs on trees. These have been failures, except where punctures through the cuticle have been made by a pin point, or where by the breaking of the leaf or some slight abrasion the skin has been ruptured, allowing the germ to enter. There are, therefore, two main meth- ods of entry by the germ. First, in the nectaries of the blossoms, and second, the tender tips of growing twigs or water- sprouts on bodies and roots. Blight occasionally enters by the third method — directly into the tender, growing, fleshy bark, through growth cracks. Sapsuckers or woodpeckers become in- fected by puncturing cases of holdover blight, and afterwards visiting healthy trees produce blight infection in them. We have several observations along this line, and doubtless many more occur in nature. It is even possible for the whiffletrees or implements used in culti-

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