134 Pflanzenkrankheiten, 



cucumber fruits showed the characteristic Spotting. These cultures 

 were also brushed on cucumber leaves, and the characteristic leaf 

 Spotting appeared. No infection occurred in check plants. Inoculation 

 into healthy female flowers caused, that the ovaries did not develop 

 any further, but turned yellow, blackened and dried up. 



In all cases a certain Pseudomonas was found to be present in 

 the tissue. The cultural characteristics are described briefly. 



M. J. Sirks (Haarlem). 



Coleman, L. C, The Control of Koleroga of the Areca 

 Palm, a disease caused by Phytophthora omnivora var. 

 Arecae. (Agric. Journ. India. X. 2. p. 129—136. April 1915.) 



The control of the disease due to Phytophthora omnivora var. 

 Arecae, which has been very prevalent in Mysore and has caused 

 considerable loss, is difficult on account of the heavy monsoon 

 rains and the height of the trees. It was found that double strength 

 Bordeaux mixture prepared with an adhesive mixture consisiing of 

 ordinary colophonium resin dissolved by heating wilh soda in 

 water, remained on the nuts sufficiently long to protect ihem from 

 infection. The difficulties of application were surmounted by the 

 use of a special type of small air-pressure sprayer. Experiments 

 already made have been so successful that there is hope of even- 

 tually stamping out the disease. E. M. Wakefield (Kew). 



Cook, M. T. and C. A. Sehwarze, A Botrytis- disease of 

 dahlias. (Phytopathology. III. p. 171 — 173. 1913.) 



The dahlia-root-rot is caused by a species of Botrytis, correspon- 

 ding very closely to the description of B. cinerea (Syn. B. vulgaris). 

 The fungus attacks the roots in storage, causing a rot, and is espe- 

 cially severe in moist places, but is of no importance if the storage 

 houses are reasonably dry and well-ventilated. When the rotting 

 roots or cultures are allowed to dry gradually, the fungus produces 

 sclerotia of various sizes. The infections are always through wounds; 

 it is impossible for them to occur through the uninjured epidermal 

 covering. The young mycelia tend to unite or conjugate by means 

 of Short mycelial tubes which usually come out at right angles. In 

 Order that this union may occur, the mycelia must be young and 

 at a distance not to exceed 10 microns. Growths similar to, or the 

 same as those described by other writers as "hold fasts" always 

 developed into sclerotia. No ascospore stage has been found. 



M. J. Sirks (Haarlem). 



Grooni, P., "Brown Oak" and its Origin. (Ann, Bot. XXIX. 

 p. 393—408. July 1915.) 



The replacement of the ordinary heart-wood by the so-called 

 „brown oak" in certain individual oak trees appears to be due to 

 the influence of a fungus. After the usual precautions as to Sterili- 

 sation, hyphae were found to grow out from the brown tissue of 

 freshly felled wood, Subsequently conidiophores developed resem- 

 bling those of a Penicillium, and "it was found possible to reproduce 

 in blocks of normal heart-wood by infection with the conidia co- 

 lours approximating to or agreeing with those of true „brown oak". 



The fungus has little power of attacking lignified walls, but 



