ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 327 



gummosis, foot-rot, dieback, Ciiuker, and withertip. Canker attacks 

 only the cortex, the others arise from troubles in the phloem and 

 cambium. The causes of these diseases have not been properly esta- 

 blished. Fungi are connected with some of them, but may not be the 

 primary cause. Bacteria may l:)e the cause of canker, but that also is 

 unproved as yet. 



H. E. Bartram * has made a study of the brown rot of stone-fruits in 

 Xorthern Vermont. The fungus causing the rot is Sderotinia cimrea, 

 along with the conidial form MoniJia cinerea. He made a series of 

 cultures, and investigated the spores of these and other forms. He dis- 

 tinguishes S. cinerea not only by the measurements of the conidia, but 

 by the absence of disjunctors, the grey colour of the conidial tufts, and 

 the persistence of the conidia through the mnter. They tlnis cause a 

 danger of infection in the early spring, when conidial tufts may be formed 

 in the first mild moist weather. 



J. Gr. C. Vriens f records the premature death of young Hevea 

 branches and of young stems, due to fungi. Attack begins at the tips 

 of the branches, and spreads back to the stems. If very young branches 

 are attacked the damage may not be serious, as the tree may recover in 

 dry weather. Tarring the infected parts is recommended. 



Stewart B. Vern % has given an account of some important leaf 

 diseases of nursery stock in the State of New York. The chief of these 

 diseases are : — Apple-scab and pear-scab, caused by species of Venturia ; 

 apple, cherry, etc., powdery mildew, due to Fodosphxra oxyacanthae, or 

 to P. leucotricha ; rose-mildew% to Sphserotheca pannosa • yellow-leaf 

 disease of cherry and plum, due to Goccomyces hiemalis, etc., or to the 

 conidial form, CyJlndrosporium ; anthracnose of currants and goose- 

 berries, due to Pseudopeziza Ribis ; Septoria leaf-spot of currants and 

 gooseberries, due to Septoria Ribis, of pears, due to S. piricola ; goose- 

 berry mildew, due to Sphserotheca mors-uvae ; leaf-blotch of horse- 

 chestnut, caused by Laestadia JEsculi ; peach leaf -curl, caused by Exoascus 

 deformans ; leaf -blight of pear and quince, due to Fabraea macidata • 

 and black-spot of roses, to Actinonema Rosae. The majority of the 

 diseases can be controlled or cured by the use of Bordeaux mixture, 

 applied at intervals during the growing season. 



B. T. P. Barker and A. H. Lees§ give the results obtained in spray- 

 ing experiments for gooseberry mildew. A soft-soap and paraffin 

 emulsion, with liver-of-sulphur added, was found to be very effective. 

 The bushes were sprayed when the disease was at its height in June, 

 and it was found to be unnecessary to spray again during the summer. 

 It remains to be seen Avhether the mildew will reappear this year. 



Soilstain of the Sweet Potato. H — J. J. Taubenhaus gives the result 

 of three years' investigation of the disease of the sweet potato {Ipomcra 

 Batatas) first described by D. B. Halstead in 1890 as " scurf." It is a 



* Phytopathology, vi. (1916) pp. 71-8. 



t Med. Advis. A.tj.R.O.S. Medau, Sumatra, No. 2 (1915) pp. 19-21. Bee also 

 Bull. Agric. Intell. Rome, vi. (1915) pp. 1706-7. 



t Cornell Univ. Agric. Exper. Stat., Bull. 358 (1915) pp. 167-226. See also Bull. 

 Agric. Intell. Rome, vi. (1915) pp. 1707-8. 



§ Journ. Board Agric, xxii. (191G) pp. 1244-9. 



II Journ. Agric. Research, v. (1916) pp. 995-1001 (2 pis.). 



