652 EXPERIMENT STATION RECORD. [Vol.43 



DISEASES OP PLANTS. 



Notes on plant diseases in 1917, D. C. George (Ariz. Cown. Apr. and Hort. 

 imi. Rpt., 9 (1911), pp. 62-66, fig. i).— Alfalfa leaf spot {Cercospora medica- 

 ginis) was general in the latter part of the season 1917. Bean bacterial blight 

 (Pscndomonas phasenii) appeared on beans raised on the experimental dry farm 

 at Prescott from seed obtained in eastern States. Cotton angular leaf spot 

 (Bacterium malvacearum) shows three forms which are described. Alternaria 

 leaf spot (Alternaria sp.) was abundant late in the season. Texas cotton root 

 rot (Ozonium omnivorum) is said to be the most serious disease of cotton in 

 Arizona. In connection with a study of this disease, observations were made 

 on the so-called conidial stage known as Phymatotrichum omnivorum. 



Potato black scurf (Rhizoctonia spp.) appeared on 65 per cent of potatoes ex- 

 hibited at the State Fair of 1917. Scab was also prevalent in some potato- 

 growing districts. Dodder is reported as parasitic on citrus and olive. Gum- 

 mosJs of stone fruit trees is said to have been quite prevalent throughout the 

 State. 



Report on the occurrence of insect and fungus pests on plants in Eng- 

 land and Wales in the year 1917, T. H. Miduleton (Bd. Agr. and Fisheries 

 [London], Misc. Pith. 21 (1918), pp. 32).— A general account dealing with condi 

 tions during 1917 is followed by a special account regarding insects and fungi 

 as related to cereals, potatoes, roots, h gumes, pasture and forage crops, vege- 

 tables, and fruit. 



The development of some plant diseases during dry weather, J. Capxjs 

 (Rev. Vitic, 1(9 (1918), No. 1258, pp. 82, S.3).— This deals with the influence of 

 dry weather on grape black rot, a disease of plane tree caused by Gnomonia 

 veneta, and wheat rust. 



Report on work done for the Province of Bengal by the Mycological 

 Section, Agricultural Research Institute, Pusa, during the year ending 

 31st March, 19 18, E. .T. Butler (Ann. Rpts. Expert Off. De.pt. Agr., Bengal. 

 1918, pp. 92-94). — Ufra disease of rice appears to be sometimes conveyed by seed 

 from an infected crop. I>aboratory work at Pusa shows that the nematode 

 Tylenclms angnstus moves freely on glass slides at a relative humidity of 95 

 (temperature 87 to 90° F.) but not at all at 90, the maximum point being about 

 93. On the plant the lower limit is between 75 and 90. The influence of nour- 

 ishment on the nematode is discussed. Starvation is a most important factor, 

 increasing the tendency of the nematodes to wander. This conies into play as 

 the crop ripens, since the nematodes feed only on the unripe plant. Ripening 

 infected Aus paddy must, therefore, be a source of great danger to Ihe neighbor- 

 ing Aman crop. Studies of the effects of the practice of burning the stubble 

 showed inconclusive results. 



Soft rot of ginger has been shown to be duv^ to Pythium graeile, which also 

 causes a .serious stem disease of papaya and attacks tobacco seedlings. 



Black band disease of jute (Corchorus capsvlaris) is ascribed to a fungus 

 supposed to be identical with that known as Diplodia eorchori. Since 1910 

 this organism has been known to occur on jute, but until 1917 it was thought to 

 be only an occasional parasite. 



Sal root rot inoculations on young trees at Dehra Dun have not yielded results. 

 A further series of infections has been started. 



Plant patliology [Nigeria], W. H. .Toiinson (Ann. Rpt. Agr. Dept. South. 

 Provs., Nigeria, 1918, pp. 18, 19). — In this portion of a more extended report, 

 several cases are noted in which oil palms were killed by Fomes lucidus. A 

 fungus attacking yams in the Okigwi district was determined as Bagnisiopsis 



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