DISEASES OF PLANTS. 151 



Pink disease, F. T. Brooks and A. Sharples (Dept. Agr. Fed. Malay States 

 Bui. 21 {1914), PP- 27, pis. 13). — The present paper embodies tlie results of an 

 investigation begun early in 1914 regarding the pink disease of rubber trees on 

 Malayan rubber estates, where it has developed considerably since 1912. some 

 estates showing attack in from 10 to 25 per cent of the trees. A preliminary 

 account of this work has already been noted (E. S. R. 32, p. 54). 



The causal fungus, Corticium sahnonicolor, has been known by various names 

 since 1S97 and is said to have been found on as many as 141 si>ecies of plants 

 distributed among 104 genera and many families. It is supposedly native in 

 most countries where it is found. Hevea brasiliensis appears to be the most 

 often attacked of its hosts in Malaya, the chief centers named being at present 

 in the district of heaviest rainfall, where large areas of jungle are still found. 



Trees over two years of age are the ones most attacked. Favorite points are 

 the forks, the shady portions of the trunk, and, in general, healthy bark 

 wherever moisture lingers, the attack decreasing in dry weather, with partial 

 or total recovery of the trees. The external manifestations, which may vary 

 considerably, are described, also the effects on the deeper tissues. The spread 

 of the fungus into the trunk affects the water supply, browning and killing the 

 foliage and in the end sometimes the tree. The fungus readily passes from one 

 host to another under favorable conditions in wet weather. 



Spraying is impracticable in most cases, owing to the size of the trees 

 affected, the heavy rainfall, and the burrowing habits of the fungus. Precau- 

 tionary painting of young trees with Bordeaux mixture has been found to reduce 

 the percentage of attack. Estates infected to the extent of 1 per cent would, 

 it is thought, better be dealt with by cutting out or by tarring as directed. 

 When burning is impracticable, infected branches cut away should be disin- 

 fected with 10 per cent copper sulphate, then removed and buried. The utmost 

 vigilance is necessary in regions affected. 



A study on a " mottled " disease of the black wattle, P. A. van der Btl 

 (Union So. Africa Dept. Agr. Sci. Bui. 4 (1914), PP- 20, figs. 9).— Mottling in 

 Acacia mollissima, decreasing its tannin content and economic value, is 

 described and discussed in its several aspects and bearings. It is said to be 

 due to physiological derangements caused by unfavorable conditions of growth. 



Control of dry rot, Moormann (Osndhts. Ingen., 37 (1914), No. 28, pp. 533- 

 536, figs. 9). — Some observations are described to show that MeruUus lacry- 

 mans may be dried out and its activity arrested completely by providing free 

 circulation of air through the .spaces beneath floors, etc., within which the 

 fungus otherwise flourishes. 



The dry-rot question, R. Falck (Gsndhts. Ingen., 37 (1914), No. 51, pp. 846- 

 8)9, fig- 1). — This is a discussion, partly critical, supplementing the above 

 report. 



Internal therapy of plants, A. Dement'ev (Zhur. Opytn. Agron. (Russ. 

 Jour. Expt. Landw.), 15 (1914), No. 4, pp. 282-293). — In experiments with 

 plants taking up through cut surfaces salts from solutions under pressures of 

 one to eight atmospheres, and under other conditions, the author found that 

 these substances are taken up at different rates and concentrations, both by the 

 same and different plants, and often in other concentrations than those existing 

 in the solutions offered. He is convinced that these facts may be utilized in 

 combating parasites by a system of internal therapy. 



Investigations on Bordeaux mixtures, B. T. P, Barker and C. T, Giming- 

 ham (Univ. Bristol, Ann. Rpt. Agr. and Ilort. Research Sta., 1913, pp. 56-66). — 

 This is a sinnmary of a number of papers by the same authors, which have 

 been previously noted (E, S. R., 25, p. 45S; 31, p. 541; 32, p. 243). 



