390 PATHOLOGY [Bot. Absts. 



circumstances in the field might produce extreme optimum conditions that would lead to 

 infection of highly resistant host plants which,, under ordinary circumstances, would be 

 regarded as immune. Lesions on such hosts then would be capable of serving as sources of 

 reinfection to citrus plants. — A. H. Chivers. 



2682. Leiby, H. W. The spraying of Irish potatoes. North Carolina Dept. Agric. Bull. 

 254:5-38. 10 fig. 1919. — This paper contains the results of five years' (1913-1918) experi- 

 mental treatment to control insects and foliage diseases of Irish potatoes in North Carolina. 

 Yields are shown from plots receiving no treatment to prevent diseases and injury from 

 potato beetles in comparison with those which were sprayed with Bordeaux mixture, with 

 Bordeaux mixture to which lead arsenate was added and with plots from which beetles were 

 removed by hand picking. — R. A. Jehle. 



2683. Leone, G. II marciume radicale degli agrumi nellOasi di Tripoli. [A root rot of 

 orange in Tripoli.] Agric. Colon. Firenze 12: 209-216. 4 fid- 1918. — The first symptoms of 

 the disease, stunted development, slight yellowing of the foliage, abundant flowering followed 

 by dropping of flowers and fruit, and a partial, then complete loss of leaves, do not become 

 evident until the root rot has reached an advanced stage. Upon examination roots appear 

 blackened, soft, and spongy, with white patches of mycelium beneath the bark. Attacked 

 trees are usually killed, so that the trouble is a serious menace to citrus cultivation in Tri- 

 poli. It is probably due chiefly to excessive irrigation and it is therefore advised that the 

 water supply be reduced to the minimum requirement. Use of healthy stock for grafting, 

 and of mineral rather than organic fertilizers are also recommended. — E. K. Cash. 



2684. Liautard. Preparation des bouillies cupriques et cupro-arsenicales. [Preparation 

 of copper and copper-arsenic sprays.] Prog. Agric. et Vitic, 69:585-590. 2 fig. 1918. — For 

 use in vineyards of Algeria in the control of downy mildew and insect pests. — D. Reddick. 



2685. LoNfi, Frances Louise. The quantitative determination of photosynthetic activity 

 in plants. Physiol. Res. 2:277-300. June, 1919. [Serial no. 16.] — Parasitic fungi and ani- 

 mals found to decrease net photosynthetic activity of leaves. [See Bot. Absts. 3, Entries 

 1375, 1452, 2833.]—/?. E. Livingston. 



2686. Mangin, L.— Action nocive des emanations de l'usine de Chedde sur la vegetation. 

 [The injurious effect of gasses from the Chedde factory on vegetation.] Bull. Soc. Path. Veg. 

 France 5: 104-108. 1918. [Issued April, 1919.] — Injury to various trees growing in the 

 vicinity of a munitions factory in the Alps is reported. The gasses given off contain chlorine 

 which is said to combine with the vapor in the air, finally producing hydrochloric acid. This 

 reaches the foliage in the dew or fog and thus causes injury. Most of the frondose trees show 

 little or no injury except in the immediate vicinity of the factory. The aciculose trees 

 showed most injury. Epicea is particularly sensitive and killed in four to six years. Abies 

 and Pinus are also badly injured. The greater injury to such foliage is attributed to the 

 fact that most of the fogs in the region occur in autumn, winter and early spring when the 

 foliage has fallen from the deciduous trees.— C. R. Shear. 



2687. Mangin, L. Sur le deperissement des Epicea dans la vallee de l'Arve (Chedde et 

 Chamonix). [The death of spruces in the Arve Valley.] Compt. Hend. Acad. Agric. France 

 5: 195-204. 6 fig. 1919. — This is the full paper, of which a discussion (by Mangin, Vincey, 

 Halleu. and Hennegtjy) appeared elsewhere. [See Bot. Absts. 3, Entry 1179.] According 

 to this author, beginning at the tips of the twigs the foliage turns yellow, then dies and falls 

 off. No leaf, stem or root parasites are present. The suspicion that was expressed in the 

 discussion, that this was due to chlorine fumes, seems unfounded since it is also present in 

 other valleys where factories are absent. Apparently a physiological trouble, probably 

 bearing some relation to the dryness of the soil and the altitude i f the locality. — E. A. Bessey. 



