June, 1920] PATHOLOGY 389 



rot of the grape, a Btem rot and also injures leaves ami Bhoots. The disease may he con- 

 trolled by applications Of nicotine soap emulsion :is used against Saiierwurm (CochyHs), 

 but being unobtainable during the war, all one could do was to provide good circulation of air 

 in the vineyards. — //. T. Gussov. 



267G. K[ikchnkk], O. [Rev. of : Appkl, O. Die Blattrollkrankheit der Kartoffeln. (The 

 leaf-roll disease of potatoes.) Deutsche Landw. Presse 45. 1918. No. 14, with art supple- 

 ment.] Zeitschr. Pflanzenkrankh. 29: 51. 1919. — Separating all diseases previously confused 

 with leaf roll (vascular, wilt, and diseases of the base of the stem), author discusses symp- 

 toms of true leafroll disease, represented by a colored plate. The cause has not yet been 

 determined, but change of seed should be practised as control measure. — //. T. Gussou-. 



2677. Koch, G. Ein fur Oesterreich neuer schadling auf Picea pungens. [A new disease 

 on P. p. in Austria.] Oesterr. Gartenzeit. 13: 147-148. 2 fig. 1918.— Buds curl up and are 

 covered with black fructifications of Cucwbitaria piceae. Disease occurs also on Finns 

 -picea. [From abst. by Matotjschek in Bot. Centbl. 140:202. 1919. J— D. Reddick. 



2678. Laffer, H. E. Disease of the vine. Downy mildew (Plasmopara viticola). Agric. 

 Gaz. New South Wales 29: 581-584. 1918.— The disease has appeared lately in New South 

 Wales. — Owing to climatic conditions it is not thought that the disease will be particularly 

 serious, the current wet season being regarded as unusual. — D. Reddick. 



2679. Lauritzen, J. I. The relation of temperature and humidity to infection by certain 

 fungi. Phytopath. 9: 7-35. 1919. — -Pathogens and host plants used were Puccinia graminis 

 var. tritici on Triticum sativum; Ascochyta fagopyrum on Fagopyrum esculenlum; Colleto~ 

 trichina lindemuthianum on Phaseolus vulgaris. A description of a double-walled humidity 

 and temperature infection chamber in which the temperature could be maintained within 

 1° F., is given. The humidifying was accomplished by open pans of water or saturated salt 

 solutions in combination with temperature manipulations. — Puccinia graminis showed a 

 temperature range for infection of 42°-80° F.; a humidity range of 95-100 per cent relative 

 humidity. Ascochyta fagopyrum showed a temperature range for infection of 45°-100° 1'.; 

 a humidity range of 90-100 per cent. Colletotrichum lindemuthianum showed a temperature 

 range for infection of 57-S0 F.; a humidity range of 92-100 per cent. — A film of water cover- 

 ing the surface of the leaf is not regarded as essential for infection but plants with a dry 

 surface show a narrower humidity range for infection. — L. K. Bartholomew. 



2680. Ledeboer, F. Voorloopig bericht omtrent de verbreiding der Gomziekte. [Pre- 

 liminary report on the spread of gum disease.] Arch. Suikerindust. Nederlandsch-Indie 

 18: 956-961. 1919. — -The spread of the disease was found to occur principally by means of 

 the chopping knife in making the cuttings. In an extensive experiment where the knife was 

 contaminated by first cutting diseased and thereafter healthy cane 94 per cent of the plants 

 from the latter became diseased whereas there was only 0.3 per cent where the knife was not 

 previously contaminated. No benefit was obtained when cuttings made with an infested 

 knife were treated with tar or bordeaux mixture. Removal of all diseased nursery plants 

 early in the season is recommended. — R. D. Rands. 



2681. Lee, H. Atherton, and E. D. Merrill. The susceptibility of a non-rutaceous 

 host to citrus canker. Science 49: 499-500. May, 1919.— Citrus canker is a disease recently 

 introduced into the gulf states from Japan. At present, attempts are being made to eradi- 

 cate the disease by burning trees on which infections are found, thus eliminating the sources 

 of new infections. The senior writer has shown that citrus canker affects plants of a num- 

 ber of other genera of the Rutaceae. More recently inoculations with Pseudomonas citri 

 on the lansones (Lansium domesticum) of the Meliaceae have produced swellings which later 

 cracked. Eruption of tissues followed. The organism was reisolated. The results of the 

 experiment warrant the statement that P. citri, upon stem tissue of Lansium domesticum, 

 produces a reaction not evidenced in control inoculations. It is conceivable that a chain of 



