172 PATHOLOGY [Bot. Absts. 



tions which favor the particular behaviour of the diseased trees: (1) compact subsoil; (2) 

 diminished resitance of the bitter orange; (3) overcrowding of the trees in the orchard; (4) 

 excessive and irrational irrigation; (5) excessive manuring, a cause that acts by destroying 

 the normal balances in the plants; (6) special cultural practices aiming at the "forcing" of 

 the trees. The author states that investigations are under way for the trial of Citrus trifo- 

 liata and C. limonellus as subjects to the grafting of orange and lemon respectively. — A. 

 Bonazzi. 



1195. Schoevers, T. A. C. Proeven met eenige chemicalien ter bestrijding van het wortel- 

 aaltje (Heterodera radicicola Greef). [Experiments with chemicals for the control of Hetero- 

 dera radicicola.] Meded. Landbouwhoogeschool, Wageningen 15: 85-88. 1918. — The author 

 reports results of further experiments on the control of the root-knot nematode, Heterodera 

 radicicola by applying various chemicals to pots of infested soil. He states that on the roots 

 of tomato plants grown in those pots treated with formaldehyde and with lime mixed with 

 ammonium sulphate no infection was found, but that slight infection occurred where naph- 

 thaline and carbolineum were applied. The other chemicals tested did not appreciably 

 reduce infection. — L. P. Byars. 



1196. Spafford, W. J. Wheat and its diseases. Jour. Agric. S. Australia 21: 947-949. 

 1918. — The smuts, rust and take-all are described. — D. Reddick. 



1197. Sternon, F. Une maladie nouvelle du Dahlia. [New disease of dahlia.] 5 p., 1 pi. 

 Bruxelles, 1918. — A leaf spot of Dahlia, attributed to Entyloma Calendulae which appeared 

 at Gembloux, Belgium, is marked by scattered, sparse, 5 to 7 mm. discolored areas, which 

 later enlarge and become confluent. These spots contain great numbers of double-walled 

 chlamydospores about 13jt in diameter with remarkably refrangible contents. These spores 

 germinate and form a promycelium with four basidiospores. No conida were observed. — 

 W. A. Orton 



1198. Taylor, W. H. Silver-leaf disease in fruit trees. New Zealand Jour. Agric. 18: 

 88. 1919. — It is stated that silver-leaf or silver blight (caused by Stereum purpureum, a wound 

 parasite) is one of the most formidable diseases which orchardists have to encounter and that 

 no cure has been found. Drastic treatment in early stages by severe pruning, and in later 

 stages by removing and destroying the trees including the roots, is advised. — E. R. Hodson. 



1199. Tunstall, A. C. Tea roots. II. 17 p., 7 pi. India Tea Association, 1918. — Dis- 

 eases of tea roots caused by the fungi, Hymenochaete noxia, Ustulina zonata, Rosellinia both- 

 rina, Sphaerostilbe repens, and Thyradaria tarda, result often in great losses. Symptoms of 

 each disease are listed, followed by a detailed description of fungus and host relations. All 

 the fungi are partly saprophytic, living as such mostly on dead stumps; hence are most abun- 

 dant in forest areas. Thyradaria tarda, Ustulina zonata, and Hymenochaete noxia cause 

 greater loss in sandy soil, while Rosellinia sp. and Sphaerostible repens have been observed 

 only in heavy soils. All the fungi excepting Thyradaria may spread through the soil. Con- 

 trol measures: Encircle diseased plants with a trench and surrounding plants by a second 

 trench. Remove and burn roots, add lime to soil where plants are attacked by Rosellinia 

 sp. and Sphaerostilbe repens, and treat wounded or pruned surface in gardens where plants 

 are diseased with Thyradaria. — J. I. Lauritzen. 



1200. Vermorel and Dantony. Les bouillies sulfo-calciques. [Lime-sulfur sprays.] 

 Compt. Rend. Acad. Agric. France 1919: 161-164. 1919. — The various lime-sulfur sprays con- 

 tain in solution hyposulfite, tetrasulfide, pentasulfi.de and oxysulfides of lime; the sediments 

 contain sulfur, lime, sulfite of lime, sulfate of lime, and oxysulfide of lime. The relative 

 proportions depend upon the temperature and length of boiling, proportion of lime and sulfur, 

 amount of water, length of cooling, surface exposed to the air, impurities in the lime, etc. — 

 E. A. Bessey. 



1201. Weir, James E., and Ernest E. Hubert. The influence of thinning on western 

 hemlock and grand fir infected with Echinodontium tinctorium. Jour. Forestry 17: 21-35. 

 1919. 



