1W6] DISEASES OF PLANTS. 847 



A disease of cold frame parsley caused by Sclerotinla libertiana, J. A. Mo- 

 Clintock {Tirginia Truck Sta. Bui. 18 (1916), pp. S19-SiH, figs. 5).— A descrip- 

 tion is given of a disease of parsley due to S. libertiana, with suggestions for its 

 control. The conditions under which parsley is grown for winter markets in cold 

 frames are said to favor the rapid development and spread of the fungus, the 

 plants being started in the open and covered with cold frames that are difficult of 

 ventilation during the freezing weather. 



As a result of the observations reported, ventilation of the frames Is deemed 

 beneficial in preventing the spread of the disease. Removing diseased plants and 

 drenching the soil with a 40 per cent solution of formaldehyde and sterilizing 

 the soil with steam are also recommended, the latter method destroying the 

 organisms occupying the soil. 



A bacterial stem blight of field and garden peas, W. G. Sackett (Colorado 

 Sta. Bui. 218 (1916), pp. S-43, pis. 3, figs. S).—A description is given of bacterial 

 stem blight of field and garden peas that is said to occur generally throughout 

 the San Luis Valley and northern Colorado and to a limited extent in Nebraska, 

 South Dakota, and Utah. The disease is characterized by the watery, olive- 

 brown color of the stems, and by the yellowish, bruised, and watery looking 

 stipules and leaflets. Where a severe outbreak occurs when the plants are 

 young, the stand may be reduced one-third or more. 



This blight is said to be caused by Pseudomonas pisi n. sp., a technical descrip- 

 tion of which is given. The organism enters the tissue through the stomata and 

 through wounds produced by mechanical injury, and is pathogenic to field and 

 garden peas, but not to alfalfa, yellow sweet clover, crimson clover, mammoth 

 clover, cowpeas, and garden beans. In the progress of this investigation, varying 

 resistance to attack was noted, and the author states that planting resistant 

 varieties offers the most satisfactory remedy for this trouble, although later 

 planting than usual may somewhat reduce the amount of injury. 



Control of the powdery dry rot of western potatoes caused by Fusarium 

 trichothecioides, O. A. Pratt (JJ. S. Dept. Agr., Jour. Agr. Research, 6 (1916), 

 No. 21, pp. 817-881, pi. 1). — The results of an investigation of the powdery dry 

 rot of potatoes are given, the work having been carried on partly In Idaho. 

 Powdery dry rot, due to F. trichothecioides, is said to be the most important 

 storage rot infecting potatoes in the irrigated West. Under ordinary western 

 field conditions, the fungus does not attack the growing potato plant, and pota- 

 toes in storage are only attacked through bruises. Planting Infected seed 

 potatoes was found to reduce the stand greatly, although a slight amount of 

 infection in the seed pieces did not cause any serious loss. The causal organism 

 is believed to be well distributed throughout western desert soils. It does not 

 develop below a temperature of 2° C. (35" F.), and in dry, well ventilated 

 storage houses, loss would be very slight at temperatures of from 2 to 4°. 



When it is necessary to store potatoes in poorly cooled or Improperly venti- 

 lated storage houses, the disease may be effectively checked by disinfecting the 

 stock, within 24 hours after digging, with a solution of corrosive sublimate or 

 formaldehyde. 



Infection of timothy by Puccinia graminis, E. C. Stakman and F. J. Pte- 

 MEISEL (U. S. Dept. Agr., Jour. Agr. Research, 6 (1916), No. 21, pp. 813-816).— 

 In a communication from the Minnesota Experiment Station, the authors report 

 having found it possible by means of artificial inoculations to infect various 

 strains of timothy with P. graminis aven<E. This host is said to exert an ap- 

 preciable effect on the morphology of the spores of the fungus, reducing them 

 considerably in size. The rust develops subnormally on timothy and the 

 postoles always remain small. These facts are believed to be suggestive as to 



