DISEASES OP PLANTS. 445 



Apple canker, S. P. Wiltshire {Ah.s. hi ilard. Ghron., 3. set:, 56 (IDUf), No. 

 ]/f60, p. JfOl).— The author reports that the wound parasite Nectria dltissima 

 invaruibly induces infection if the wound through which it enters is deep 

 enough to penetrate to or nearly to the wood ; otherwise protective tissue is 

 formed and the parasite is exchided from the living tissues. It is said that the 

 disease is generally localized, though the capability of the fungus to spread 

 from one part to another has not yet been determined. It is claimed that there 

 is no danger of communicating the disease by grafting provided the graft is 

 taken from a healthy shoot. 



An algal disease of cacao, W. G. Frekman (Bui. Dept. Agr. TrhiUlad and 

 Tobago, l,i {lUlJf), No. S-h pp. 203, 2(1'/). — Notes are given on the occurrence of 

 a disease of cacao due to ih'phaleuroi< rirescen.t. The disease is said to be 

 manifested by a dying back of the shoots and is particularly characterized by 

 the leaves turning brown, but not falling, so that trees badly attacked are 

 covered by dead twigs and brown leaves. 



In addition to occurring on the cacao this alga has been reported as doing 

 considerable damage to mangoes and to other tropical trees, as well as on tea in 

 India. 



Operations against cacao canker, C. J. J. van Hall {Medcd. Proef.^tat. 

 Middcn-Jaca, No. 14 (1914), pp. 10). — This is a I'eport of observations on the 

 spread and effects of cacao canker in the vicinity of Pekalougan from 1908 to 

 1914, also of attempts there during the last two years to control the disease, 

 which is favored by wet weather, but appears to abate during the dry season. 

 The organism not only attacks wounded areas but uninjured parts also. 



The use of Bordeaux mixture, especially on two experimental areas as de- 

 .scribed, reduced considerably in one year's time the number of trees showing 

 canker in the wet months of January and February. 



Black spot of the mandarin (Queensland Agr. Jour., n. ser., 2 (1914), No. 2, 

 pp. 143, 144). — Advice pending results of test experiments in progress is given 

 to orchardists. Trees are to be pruned radically on every appearance of dis- 

 ease, all of the prunings being destroyed by fire. Several spraying mixtures are 

 recommended, with directions as to proportion, strength, and times of appli- 

 cation. See also a previous note (E. S. R., 31, p. 843). 



American gooseberry mildew, T. H. Middleton (Bd. Agr. and Fisherie.<i 

 [London], Ann. Rpt. Ilort. Branch, 1913-14, PP- 10-3S). — A report is given of 

 the investigations carried on concerning the American gooseberry mildew under 

 the Destructive Insects and Pests Acts, in which the relation of weather con- 

 ditions to the appearance and development of the mildew, occurrence of the 

 disease on the fruit, state of the disease in various affected districts, and effect 

 of spraying on the control of the disease are described. 



In the spraying experiments different strengths of lime sulphur, potassium, 

 sulphid, and Bordeaux mixture were used, but inspectors who visited the 

 premises at different times were convinced that the benefits resulting from 

 spraying were not commensurate with the cost. No spray material has proved 

 so successful in permanently reducing the disease as has the expedient of re- 

 moving and destroying the infected shoots as soon as the bushes have stopped 

 making growth. 



The treatment of court-noue by tar, J. Bektrand (Bui. Agr. Algerie, Tunisie, 

 Maroc, 20 (1914), No. 1, pp. 15-20). — The author, citing experiments that have 

 been carried on for several years, states that coal tar may be successfully used 

 for the treatment of couit-noue. The affected vines should be prunwl and cov- 

 ered with tar very shortly after the pruning, the same day if possible. Care 

 should be taken that the .stock be well covered, but the tar must not come in con- 

 tact with the buds, as it is said to destroy them. 



