. Ontario Sessional Papers, 1919, . Fig. 12.—Trees defoliated by May-beetles {Lachnosterna spp.). The treesin centre are bur oak and the tree to right an Fig. 13.—Hickory woodlot defoliated by May-beetles {Lachnosterna spp.).The undefoliated tree to left is an apple. 60 TlIK IJEIMJIJT OF TITK Xo. 36 INSECTS AS AGENTS IN THE DISSEMINATION OF PLANT Caesak, 0. A. C, Guelph. The following was delivered as the Presidents Address: There are three great classes of plant diseases in the dissemination of whichinsects play a part. These are:—first, diseases due to fungi; s
. Ontario Sessional Papers, 1919, . Fig. 12.—Trees defoliated by May-beetles {Lachnosterna spp.). The treesin centre are bur oak and the tree to right an Fig. 13.—Hickory woodlot defoliated by May-beetles {Lachnosterna spp.).The undefoliated tree to left is an apple. 60 TlIK IJEIMJIJT OF TITK Xo. 36 INSECTS AS AGENTS IN THE DISSEMINATION OF PLANT Caesak, 0. A. C, Guelph. The following was delivered as the Presidents Address: There are three great classes of plant diseases in the dissemination of whichinsects play a part. These are:—first, diseases due to fungi; second, diseasesdue to bacteria; and third, diseases whose cause has not been discovered but whichare of a decidedly communicable or infectious character. This last class is oftencalled Physiological Diseases, or Diseases of Unknown Origin, the latter termbeing preferable. Before discussing the role of insects as disseminators it may be well to givea list of the common agents in the spread of pliant diseases. They are: wind, rain(especially wind-driven rain), infected seed, infected manure, infected soil, insects,slugs, man with his teams and implements, bird
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