548 EXPEKIMENT STATION RECORD. 



ically is placed upon a normal leaf of such a plant as lettuce, infection spreads 

 rapidly. 



Experiments were undertaken to ascertain whether conidia could cause the 

 infection of plants weakened in various ways. Lettuce plants were grown in 

 sterilized sand which was watered from time to time with different minei-al 

 solutions. One group of plants received a complete fertilizer, and others solu- 

 tions containing I'espectively no nitrogen, phosphorus, potassium, and mag- 

 nesium. The plants of these groups after growing six weeks were subjected 

 to conidia of Botrytis without infection. 



It was found that by tearing the healthy green leaves of lettuce plants infec- 

 tion was readily caused when spores were placed upon the torn portions. The 

 conidia were also found able to infect leaves that were beginning to turn yel- 

 low, whether the yellowing occurred in ordinarj- light or when the plants were 

 placed in darkness. 



Cotton wilt, n. R. Fulton (Loiiislann Htas. Bid. 0(1, piK 15, pis. 3). — A gen- 

 eral summary is given of information relating to the wilt, blackheart, or black 

 root of cotton, caused by the fungus Xcocosniospora rasinfccta. Especial atten- 

 tion is called to the use of resistant strains of cotton in combating this disease 

 and suggestions are given for their breeding. 



Prevention of sorghum and Kafir corn smut, H. F. Roberts and G. F. Free- 

 man {Kansas >S7«. Bui. JJ/O, pp. ll-h'>, dgm. 1). — During the summer of 190G a 

 series of experiments were carried on at the station to determine means for 

 the control of the grain smut of sorghum and Katir corn due to Cintractia 

 snrghi-viih/aris. These experiments consisted of tests of different strengths of 

 formaldehyde, and it api)ears that the spores of the fungus can be destroyed 

 by soaking the seed for 12 hours in a 0.2 per cent formaldehyde solution, or for 

 2 hours in a 0.5 per cent solution. The cost of the treatment is estimated at 

 about G cts. ijer bushel of seed treated. 



The present state of our knowledge regarding potato diseases and their 

 control, O. Appel and W. Kreitz {Mitt. K. BioL A list. Land u. Forstir., J907, 

 \(j. J, pp. 31, pgs. IS; abs. in Dent. Landiv. Prcsse, S.'f {1907), No. 8.'/, pp. 66.'i, 

 673.7). — Compiled notes are given describing the more important diseas(^s of the 

 l)otato, the time of their appearance, conditions for the development of the 

 diseases, and means for their prevention. , 



A bacterial disease of potatoes, O. Appel (A'. Biol. Ansi. Land ii. Forstw. 

 Flughl. 36, pp. J/, figs. 2). — A bacterial disease of potatoes is described, the most 

 striking characteristic of which is a darkened zone within the tubers that corre- 

 sponds in the beginning with the fibrovascular layer of the tuber, from which 

 is derived the name ring disease. Later the infection spreads and other portions 

 of the tuber become involved. The above-ground portions of the infected plants 

 are stunted in growth, the flowers greatly reduced in size, the lower leaves 

 die, and the whole api)earance of the plant is changed. 



According to the author, the disease does not seem to be caused by a single 

 species of bacteria but by a number of closely related forms that are common 

 in the soil. The abundance of these bacteria depends upon weather and mois- 

 ture conditions, and they appear to readily gain entrance to the plant through 

 freshly cut surfaces of tubers or accidental injuries to the growing plants. All 

 tubers showing dark rings should be rejected and the cut tubers should be 

 allowed to dry for a day or two before planting. 



Some apple diseases, F. L. Stevens and J. G. Hall {XortJi Carolina Sta. Bid. 

 196, pp. 39-0.'). figs. 5). — Notes are given on a number of diseases of the apple, 

 of which the Volutella rot has been previously described (E. S. R., 19, p. 49). 



The present account gives in detail some of the characters of this fungus. It 

 is believed that thorough spraj'iug would control the disease. 



