250 EXPERIMENT STATION EECORD. 



The period when most apple root grafts become diseased with crown gall is 

 when the wounds in the union are being healed by the formation of callus. 

 The disease apparently does not spread from tree to tree in the nursery rows, 

 since there was little or no increase of disease after the first year. Root grafts 

 should be carefully fitted, especially with respect to the lower end of the scion, 

 ' which should have a sharp rather than a blunt end. The wrapping used should 

 cover the union completely and should firmly hold the parts together until the 

 graft is planted in the soil, and then should rot away when growth begins. 



Crown gall and hairy root of apple trees is principally a nursery disease, 

 gaining entrance most frequently during the first year. In order to keep the 

 nursery as free as possible from it, all diseased trees should be left in the 

 field at the time of digging, and burned as soon as dry. Scions from healthy 

 trees and stocks from seed from sound trees only should be used. Root grafts 

 should preferably be stored in sand, and if the period of planting is delayed 

 beyond two weeks, they should be stored at a temperature a few degrees above 

 the freezing point. Such varieties as the Wealthy, Yellow Transparent, Wolf 

 River, Ben Davis, and Northern Spy, which are quite susceptible to crown gall 

 and hairy root, should be propagated by budding. Growers of seedlings should 

 avoid wounding the young trees during cultivation. 



A bibliography is appended. 



Some obscure diseases of the peach, J. B. S. Norton {Jour. Econ. Ent., 3 

 (1910), No. 2, pp. 22S-236). — The author briefly describes a number of diseases 

 of the peach, the exact cause of which is not known or that are of unusual 

 occurrence. Among those described are yellows, rosette, little peach, silver 

 leaf, split pit, root rot, gummosis, canker, shot hole, leaf spot, chlorisis, leaf 

 roll, wilt, leaf and fruit drop, twig spot, and twig blight. 



Little peach disease, L. Caesar (Ontario Dept. Agr. Bui. 185, pp. S). — The 

 author summarizes the known facts about little peach, compares its symptoms 

 with those of peach yellows, discusses little peach and its ravages in Michigan, 

 and closes with recommendations to Ontario orchardists concerning its control. 



Persistent and careful yearly inspection looking to its complete eradication 

 by the prompt destruction of all infected trees is the only remedy advised. 



Experiments with nitrate of silver in combating- the grape mildew, I^aber- 

 GERiE (Jour. Agr. Prat., n. ser., 20 (1910), No. 38, pp. 369, 370).— In testing 

 the efllciency of this new silver spray (E. S. R., 24, p. 51) in combating the 

 mildew, two varieties of grapes, one very susceptible and the other fairly 

 resistant to its attack, were used. Both plats received 4 applications of Bor- 

 deaux mixture previous to spraying with the silver nitrate solution, and the 

 results were compared with those obtained with the regular Bordeaux mixture. 



The silver nitrate in neither case proved effective against the mildew, show- 

 ing a marked inferiority to the Bordeaux mixture in this respect. 



A bacterial disease of bananas and plantains, J. B. Rorer (In Proc. Agr. 

 Soc. Trinidad and Tobago, 10 (1910), No. 4). — The author describes a disease 

 of bananas and plantains which has become rather destructive in Trinidad. 

 The disease is characterized by the drooping of the leaves, and sections of the 

 midribs of the leaf and of the stem showed the fibrovascular bundles blackened 

 and filled with bacteria. 



An examination of a large amount of material led the author to conclude 

 that the disease was a bacterial one, and an attempt was made to isolate the 

 causative organism. Two organisms were found, one of which was a rapid gas 

 former in beef agar, while the other made a rather slow growth in all the media 

 in which it was tried. Inoculation experiments showed that the gas-forming 

 organism did not cause the disease, while in inoculations with the other species 

 the typical symptoms were produced, and the organism was reisolated. 



