DISEASES OF CULTIVATED PLANTS 595 



the fungus was the same in both cases. He furthermore ascer- 

 tained that in all cases when the beet scab was abundant, potatoes 

 had 'been grown on the soil, either the previous year or somewhat 

 earlier. Working independently, at about the same time, Profes- 

 sor Arthur came to similar conclusions about the identity of these 

 two forms of scab; and a single decisive experiment in the trans- 

 fer of scab from potato to beet was reported by him. Since that 

 time there has been abundant general evidence to establish the fact 

 that scabby beets may be expected if the seed are sown on land 

 which has recently produced scabby potatoes. 



The remedy cannot consist in this instance in the treatment 

 of the seed, since the seed do not disseminate the disease; nor can 

 it consist in the treatment of the land, since the experiments with 

 liming, sulfuring, etc., have not given satisfactory results. The 

 only course open, then, is the one of avoiding for the growth of 

 beets any soil which, during several years previous, has produced 

 scabby beets. (Cornell E. S. B. 163.) 



Root-Rot of Beets. Under favorable conditions for its spread, 

 this beet root-rot generally secures its first foothold at the bases of the 

 leaves. These parts are moist with the slightest rain or dew, and 

 inoculation experiments show that in those regions the disease takes 

 very readily. The first evidence of the attack is manifest in the 

 blackening of these leaf bases, the outer leaves first, so that the stalks 

 soon become unable longer to support the blades, and the leaves may 

 lie prostrate on the ground. The leaves do not, however, lose their 

 green color very reaaily. 



The disease soon works into the crown and root proper, caus- 

 ing the infested parts to turn brown. With further spread of the 

 fungus in the root region, cracks appear. If the conditions continue 

 to favor the disease, in time the whole top rots away, and the beet 

 gradually disappears. Cold weather or dry conditions may so retard 

 the disease that plants only slightly affected may recover entirely. 



Even when the bases of the leaves alone are affected, upon 

 careful examination one will find that there are to be seen the 

 brown mycelial threads of the fungus growing over the surface. 

 After the root has become affected, a considerable weft of the fun- 

 gus will be evident in the cracks. A diseased beet sliced lengthwise 

 and placed in a moist chamber yields in a day or two a luxuriant 

 growth of the mould-like hyphse. . 



The use of lime as a possible preventive for certain rhizoc- 

 tonial diseases has been recommended. The use of an alkali as 

 a preventive might be logically suggested knowing the avidity 

 with which the fungus grows on acidulated nutrient media. The 

 failure of the Rhizoctonia to cause trouble in those parts of the 

 field where coal ashes had been used abundantly again suggests 

 the same remedy. Furthermore, Mr. F. C. Stewart has determined 

 that a small amount of alkalinity is fatal to the growth of the Rhi- 

 zoctonia of carnations in cultures. In general it seems that the soils 

 of the State are usually in need of liming, and where this beet disease 

 appears it would be very well to make an application of lime. Sixty 



