Minnesota Plant Diseases. 399 



peanut. It is single-celled and produces swimming spores in 

 the early summer months. It forms small, dark, reddish galls in 

 the tissues of the host plant, quite like those formed by the gall 

 fungi of dandelion, wild peanut and cranberry, but the galls are 

 colored red as in cranberry. This fungus is very common in 

 Minnesota and is especially conspicuous in late spring and early 

 summer. It can be readily recognized by the dark, reddish col- 

 or of the host plant leaves and the small wart-like excres- 

 cences. 



Leaf wart of dandelion (Synchytrium taraxaci DcBy. et 

 Wor.\ This fungus is closely related to the fungus of the seed- 

 lingi disease of cabbages. It attacks the leaves of the dandelion 

 and stunts and distorts them. The fungus is a single spherical 

 cell and lives in one of the epidermal cells of the host. The 

 latter cell swells to many times its original size and produces 

 the simplest kind of a plant gall. The leaf when badly infected 

 contains many of these galls, so that the surface is more or less 

 roughened by the abundance of warts. Swimming spores are 

 produced in a manner similar to those of the seedljng cabbage 

 disease and spread the infection under moist conditions. Thick- 

 coated winter spores are also produced. This disease, though 

 not uncommon, is never serious enough to assist materially in 

 getting rid of the dandelion pest. 



Cranberry scald (Undetermined fungi). The life stories of 

 the fungi which cause this disease have not yet been worked 

 out. There are probably several kinds producing what is com- 

 monly known as scald. Small soft spots arise in the cranberry 

 and these soft spots enlarge rapidly until the whole berry is af- 

 fected and it now has the appearance of a scalded berry. The 

 skin remains intact but the contents are watery and soft. In 

 the diseased tissues one can find abundant threads of the fun- 

 gus. The berry in later stages turns dark brown, finally shrivels 

 and becomes black. On the surface are produced minute black- 

 spots appearing somewhat like the capsules of certain parasitic 

 burnt-wood fungi. The disease appears in July and August 

 and affects also cranberries in storage. Excessive moisture 

 seems to favor the disease. Sanding of the bogs, an inch in 

 depth, and draining in summer, so that they shall remain fairly 

 drv, have been recommended. 



