Jcne, 1920] PATHOLOGY 406 



2784. West, Fiidman. An undescribed timber decay of hemlock. Mveologia 11: 202-266. 

 1919— See Bot. Absts. 4, Entry 1188. 



2785. Westerduk, Johanna. Neueres iiber Flachskrankheiten. [Flax diseases.) 

 Jahresber. Vereinig. An^cw. Botanik 16: IS. 1918. — Flax blight, caused by /'Vsanum lini, 

 is very destructive in Holland. White-flowered flax is more resistant than blue-flowered 

 kinds. — Rust (Melampsora lini) appears in wet seasons when the phmts arc nearly mature 

 and only on white-flowered kinds. It develops best on highly fertilized, rank plants. — 

 Anthracnose (Gloeosporium lini) occurs on stem, capsule and seed. It is controlled by seed 

 treatment, for 3 hours, with formaldehyde vapor. — Iiotri/lis cincren may appear in damp weath- 

 er particularly on seedlings. — A dead-stem disease has appeared in North Holland. I'lants 

 are brown and dry. A species of Phoma occurs on many plants but not on all. [From ab- 

 stract by O. K[irchner] in Zeitschr. Pflanzenkr. 29: 121. 1919.]—/). Reddick. 



27S6. Winston, J. R., and Fulton, H. R. The field testing of copper-spray coating on 

 foliage. Better Fruit 13 12 : 9, 27-28. June, 1919. — A field test has been devised to indicate 

 the copper-spray coating on foliage. The method is as follows: 200 gm. of fresh leaves are 

 washed for 3 minutes in 1000 cc. of 0.2-per cent solution of chemically pure nitric acid in 

 water. Some of the wash water is treated with a few drops of 2-per cent solution of potassium- 

 ferrocyanide to precipitate copper. A color comparison is then made with a series of stand- 

 ard copper solutions of known strength. The latter are made by proper dilution from a 

 stock solution of 3.928 gm. of copper sulphate in water to make 1000 cc. — About 75 spraying 

 schedules, extending over two seasons, have been tested. Representative results of tests 

 on apples in Virginia and grape fruit and nursery stock in Florida are considered in detail. 

 The authors conclude that the method may be of service (1) "To secure data showing the per- 

 sistence of copper-containing sprays as it may be influenced by method of preparation, weath- 

 ering, or other factors; (2) to determine the minimum and maximum limits of working 

 safety-zones, as measured by evenly distributed residues, effective to the practical control 

 of specific diseases; (3) to secure prompt correction of faulty spraying practices, either in 

 the preparation of mixtures or in the times or modes of application; and (4) to serve as a 

 practical guide in timing new applications, especially after rainy periods." — A. E. Murneek. 



2787. Wormald, H. The brown rot diseases of fruit trees with special reference to two 

 biologic forms of Monilia cinerea Bon. I. Ann. Botany 33: 361-404. PL S5-S6. 1919.— Two 

 distinct species of Monilia (frucligena and cinerea) occur as parasites on fruit trees in England. 

 Each species has two forms, to be distinguished by the effects produced on mature apples in- 

 oculated under laboratory conditions. — M. cinerea has two biologic forms, mali and pruni, 

 the former only, being able to produce a blossom wilt and canker disease of apples. Liter- 

 ature is reviewed extensively, methods and experiments are described in detail and a lengthy 

 bibliography is appended. — D. Reddick. 



2788. Wober, A. Ueber die chemische Zusammense tzung der Kupferkalkbruhe. [Chem- 

 ical composition of Bordeaux mixture.] Zeitschr. Pflanzenkrankh. 29: 94-104. 1919. — Dis- 

 cussion of the precise chemical actions taking place in the preparation of Bordeaux mixture. 

 Alkalinity of solution is essential; acidity is easily removed by rain, and this makes Bolution 

 likely to cause damage by burning. — H. T. Giissow. 



2789. Wurth, Th. De schade aangericht door de Kloetuitbarsting op de koffie- en Rubber- 

 landen van den Kloet. [Damage to coffee and rubber by the Kloet eruption.] Proefsta. Malang 

 [Java] Circ. 7. 8 p. 1919. — Preliminary survey of the damage to 31 plantations on the slopes 

 of the Kloet volcano is given. Besides the local destruction of trees by mud streams and 

 falling stones, most of the high-lying areas showed severe scorching and death of leaves at- 

 tributed to heated air currents and also to ash rains, with possibly poisonous gases. Hard- 

 packed layer of sand and ash particles, in consequence of the presence of colloidal silicic acid, 

 caused damage by preventing entrance of air and water to the soil.- — R. D. Rands. 



2790. Zacharewicz, Ed. Traitements contre le mildiou et l'oidium. [Treatment for 

 the mildews of grapes.] Jour. Agric. Prat. 31: 127-128. 1918. 



