DISEASES OF PLANTS. 653 



The first gymptom is the appearance in the field of areas in which the plants 

 bear a more intense green color than normal, accompanied by a different posi- 

 tion of the foliage. Later the leaves become discolored and curly. 



From investigations conducted the author concludes that the disease is not 

 of parasitic origin, nor due exclusively to soil or climatic conditions, but that 

 it is probably the result of a too rapid and strong growth of the plants in con- 

 nection with the attacks of the cicads. 



Two recent important cabbage diseases of Ohio, T. F. Manns {Ohio Sta. 

 Bui. 228, pp. 255-297, figs. 26). — A study is reported of "yellows" or Fusarium 

 wilt and of blackleg or foot rot {Phoma oleracea) of cabbage, including symp- 

 toms of these diseases, methods of dissemination, losses caused by them and 

 methods of control. 



The Fusarium wilt is characterized by a yellowing of the lower, outer leaves, 

 which later drop from the plant at the slightest touch. In older plants, some- 

 times stumps nearly full size may be seen that have shed all their leaves. 

 Cross sections of infected stumps and roots, when not associated with bacterial 

 action, show a light yellowing or browning of the vessels. If bacteria are also 

 present, the vessels change to a dark brown or jet black. 



No si)eciflc treatment is known for this wilt but seed treatment with formalde- 

 hyde, new seed beds each year, the use of only the most hesilthy and vigorous 

 plants, immediate destruction of diseased plants if any should appear, rotation 

 of crops, and the rejection of manures carrying infected cabbage litter are 

 some of the means suggested for combating it. 



The usual characteristic symptoms of blackleg or Phoma rot of the cabbage 

 are described and comparisons made between the symptoms of this disease and 

 the Fusarium wilt. In addition to the same methods as those recommended 

 for combating the Fusarium wilt, a thorough spraying of the seed beds with 

 Bordeaux mixture, particularly just before transplanting is advised, as one of 

 the most active means of disseminating this disease is infection of healthy 

 plants from a few diseased ones at the time of transplanting by the smearing 

 of the spores on the healthy plants. 



A brief bibliography is appended. 



The Fusarium blight (wilt) and dry rot of the 'potato, T. F. Manns (Ohio 

 Sta. Bui. 229, pp. 299-336, figs. 18). — This is a general discussion of this disease, 

 including its history as a storage rot and as a field trouble, the cause of dry rot 

 in storage, losses from using infected seed and from sick soil conditions, studies 

 on the seed-potato condition in 1909 and 1910, culture work, and artificial inocu- 

 lation work with sick soils in the greenhouse, factors which influence the prog- 

 ress and dissemination of the disease, early versus late planting, storage condi- 

 tions for seed purposes, the length of crop rotations, care of refuse and infected 

 material, field experiments in controlling the disease, effects of sprays on 

 foliage, and remedial measures. 



It was found that the dry-rot fungus (Fusarium oxysporum) of the potato is 

 a common field trouble in Ohio, causing a blight and wilting of the crop and 

 producing a sick soil condition in many potato districts. The field symptoms 

 are a cessation of growth and a yellowing of the foliage with an upward and 

 inward rolling of the leaves, accompanied by wilt during the heat of the day. 

 The causative organism is carried within the tubers, which are the chief means 

 of distributing the disease. This internal infection of the tuber is characterized 

 by brown or black areas, usually in the fibrovascular ring. 



The use of sound seed tubers, a 5 or 6 year crop rotation, especially with 

 grass or grain crops, and the avoidance of infected barnyard manures as a fer- 

 tilizer for potato lands are some of the suggestions given for the control of this 

 disease. 



