PARASITIC RHIZOCTONIAS IN AMERICA 355 



Flats (9x12 inches) were infected as in Experiment 1, and a vary- 

 ing number of cuttings, seeds, and plants placed in them on March 7, 

 1914. Pure cultures from the diseased plants in each flat were made! 

 and Bhizoctonia was isolated in each case. Following, the results of 

 the experiment are taken up in detail. 



"Alternanthera E.A.C." on Alternant her a. 48 cuttings. On March 18 all 

 were dead. The infection \vas first noticed as a small, brown lesion on one side 

 at the surface of the ground; later the lesion girdled the whole stem. The fun- 

 gus also attacked the cut surface of the cutting, causing a lesion and in some 

 instances a slow, wet rot. The mycelium, which grew very profusely, attacked 

 the leaves, producing a characteristic rot. 



"Alternanthera R.A.F." on Alternanthera. 48 cuttings. The experiment 

 was carried out exactly like the above and produced the same results. 



"Alternanthera B.A.F." on Gernanium. 48 cuttings. These were planted 

 March 20 in the infected flat in which alternant-hero cuttings had died. By 

 May 2, 42 of them were rotted while 6 were rooted and healthy. 



"Amaranthiis" on Amaranthus salicifolius. 100 seeds. Seeds germinated 

 March 23, and by April 1 all the plants in the flat damped off in a character- 

 istic manner. 



"Aster" on Aster. 100 seeds. Seeds germinated March 18 and a few be- 

 gan immediately to damp off. By April 1, 29 percent had died, while the others 

 remained healthy. 



"Bean" on Bean. 30 Feeds. Seeds germinated March 19, and after two 

 months only 5 percent were killed by the fungus. 



"Beet" on Beet. 100 seeds. Seeds germinated March 19 and began to 

 damp off. About 25 percent damped off and later about 25 percent more be- 

 came scabby because of the formation of small, depressed lesions. Injury here 

 was similar to the infection of beet by the strains from carnation. 



"Carnation" on Bean. 50 plants. On May 8, bean plants about three 

 inches high were transplanted from flats to infected sections (Nos. 157 and 

 173). The plants took hold readily, and after about two weeks began to show 

 signs of infection. The disease progressed rather slowly; most of the plants 

 produced a few pods before they were killed by the fungus. When pulled up, 

 May 19, every one was diseased or dead (Fig. 8). A detailed description of 

 four typically infected bean plants follows. It will be seen that it corresponds 

 in most details to the descriptions given by Barrus, 9 Fulton, 43 and Hedgcock 60 



Plant No. 1: Three distinct lesions were present, one directly 

 above the other on the stem. Lesions were oval in shape with a reddish 

 brown band surrounding a lighter colored sunken area. Evidences were 

 present of young lesions over the entire stem and larger roots under- 

 ground. The wounds extended beneath the cortical layer to the woody 

 tissue. 



Plant No. 2: Eoots were infected at the joint of their union with 

 the main stem. The lateral root was very badly infected and rotted off 

 entirely. The lesions on the smaller roots were small, depressed, and of 

 a reddish brown color. 



Plant No. 3 : A large, reddish brown lesion extended from the sur- 

 face of ground downward 2.5 centimeters. Spots were sunken and ex- 

 tended thru the cortex to woody tissue beneath. Two smarl sunken areas 

 of a reddish brown color were present on the stem one inch above the sur- 

 face of the ground. 



Plant No. 4: A large, depressed, reddish brown area extended from 

 the surface of the ground downward 2.5 to 3 centimeters, almost encircling 

 the stem. Cortical tissue rotted away exposing the woody tissue beneath. 

 "Carnation" on Beet. 30 plants. On May 8, young beet plants were trans- 

 planted to a section (No. 158) infected with Rhizoctonia from carnation. By 



