DISEASES OF PLANTS. 545 



When infected seeds were planted, diseased seedlings were produced, and the 

 disease thus spread. A number of outbreaks of anthracnose in various sections 

 uf South Carolina were traced to the planting of diseased seed. 



Studies have shown that it is impossible to isolate the fungus from material 

 that has remained in the field as late as July 20. On the basis of this and 

 other observations the author believes that it will be possible to eliminate the 

 disease by a one year's rotation with disease-free seed. 



The results of seed treatment, methods of infection, resistance, etc., are 

 to be the subject of a rejxirt from the South Carolina Station. 



A serious potato disease occurring' in Newfoundland, II. T. Gtissow (Can- 

 ada Cent. Expt. Farm Bui. 63, pp. 8, pis. 2, figs. 1). — Attention is called to the 

 rapid spread throughout European countries of potato canker {Chrysophlyctis 

 endohiotica) and its recent (1909) observation in Newfoundland. The history, 

 appearance in the field, damage caused by, and the pathology of the disease, are 

 noted. In this disease the eyes of the tubers produce an abnormal cauliflower 

 or warty outgrowth from the size of a pin's head to that of the potato itself. 

 In many cases the entire potato is covered with a blackish mass of wrinkled 

 warts. 



Prevention, seeing that no diseased potatoes are used for seed, seems to be the 

 best remedy. If the seed tubers are suspected, the sets should be powdered with 

 sulphur at the rate of 4 or 5 lbs. to a ton of potatoes, and then stored in boxes 

 until planted. When the disease has once appeared in a field, the diseased 

 tubers should be collected and either burned or boiled. If boiled, they can be fed 

 to the stock, but under no conditions should unboiled or decayed potatoes be fed, 

 as the spores of the disease are capable of germinating after passing through 

 the body of an animal. 



In removing the potatoes from the field, great care should be taken to clean 

 thoroughly and disinfect boots, carts, and implements. All refuse from the vines 

 and all diseased tubers should be collected and placed in a hole upon a layer of 

 unslacked lime 6 in. deep, covered with a layer of unslacked lime, and so on until 

 the hole is full. If lime is not available, sawdust soaked in bichlorid of mercury 

 1 : 500, and mixed with the tubers in the hole may be used. When the land has 

 been thus cleaned, it should be fallowed and treated with unslacked lime at the 

 rate of 4 or 5 tons per acre, or sprayed with a solution of bichlorid of mercury, 

 1 : 800. In a four-year crop rotation the potatoes should be replaced by some 

 other crop, as, so far as is known, the disease only attacks potatoes. 



A warning is specially given to all potato growers to be on the watch for this 

 disease, as it may be introduced on imported seed potatoes from European coun- 

 ti'ies at any time. 



Infection experiments with Chrysophlyctis endobiotica, the cause of the 

 potato canker, G. Schneiuek {Dctit. Laiidir. Presse, 36 (1909), No. 88, pp. 9JfO, 

 941, figs. 6). — The author conducted a series of experiments relating to the 

 growth, characteristics, and propagation of this disease. 



It was found that the resting thick-walled sporangia withstood without in- 

 jury a temperature of —13° C. in the open air and thus were able to live 

 through the winter and in the spring of the year infect the young potato plants. 

 Remnants of diseased potatoes which were overlooked and left in tlie field were 

 often affected by the dry rot and crumbled, but the thick-walled sporangia re- 

 mained uninjured in tlie soil, and were a source of infection to the new crop. 

 The disease enters through the eyes of the potato when the tubers are young 

 and spreads from cell to cell by its Plasmodia. By this means the stems, 

 shoots, and often the leaves finally become diseased. There was no difference 

 observable in the growth of the tops of those potato plants in which tubers 

 were diseased and of those which were healthy. The disease was not affected 



