248 EXPERIMENT STATION RECORD. 



affected with leaf roll. It was found that such enlargement took place also in 

 case of potatoes not so affected, lasting for about the first 4 weeks after planting. 



Successive crops from planting affected tubers were found to diminish both 

 in number and size of tubers produced until in from 4 to 7 years the results 

 became practically nil. A few escaped from this decline and showed a tendency 

 toward normal products, which tendency is to be more fully tested. See also 

 previous notes (E. S. R., 21, p. 243; 22, p. 347). 



Bacterial rot of potato, O. Appel (Mitt, K. Biol. Anst. Land u. Forstw., 1911, 

 No. 11, pp. 12, 13; aJ)s. in CentU. Bakt. [etc.], 2. AM., 32 (1912), No. 6-12, 

 p. 319). — It is stated that a soft rot of potato tubers is caused by Bacterium 

 xanthochlorum, also that this organism causes a blackleg disease of Yicia 

 faba and a stem rot of Ltipinus mantis. The author was not able to breed from 

 B. fluorescens, which at 35° C. takes on pathogenic characters, a race cor- 

 responding to B xantJi ochloru 771. 



Investigations with potato scab, A. Beenhard (Deut. La7idw. Presse, 38 

 (1911), No. 27, p. 320; abs. w Ceiithl. Bakt. [etc.], 2. Ait., 31 (1911), No. 11-15, 

 pp. 399, JfOO). — Continuing previous investigations (E. S. R., 25, p. 245), the 

 author compared results from the use of sulphur alone with those from its use 

 in connection with lime. The all-sulphur treatment seemed the more effective. 



The results obtained from planting seed potatoes affected with scab seem to 

 forbid such use of infected tubers, while sound seed tubers in infected soil 

 showed only sporadic infection. 



Rice blig'ht, J. L. Hewitt (Arka7isas Sta. Bid. 110, pp. ^.'/7-^59). — ^A form of 

 rice blight characterized by the appearance of blighted heads at the time the 

 grain is ripening is described. 



Various theories have been proposed as to the cause of this trouble. The 

 author has investigated a number of them and has arrived at the conclusion 

 that it is due to some soil condition, probably an organic disturbance, and that 

 whatever it is that causes the disease the plant suffers through injury to the 

 root system. 



An investigation of a number of plants from badly infected and slightly in- 

 fected portions of the field and from a field which contained no blight showed 

 that the roots were injured in proportion to the amount of blight. The blight 

 appears to be associated with decaying plant d&bris in the soil, and the author 

 proposes this as a working hypothesis to be further investigated. 



For preventing the disease, the rotation of crops so as to have rice follow 

 some crop that will leave the land free from decaying debris, plowing late in 

 the fall, the burning of stubble, and such other means as are feasible to complete 

 the normal decay or removal of all straw, weeds, and trash are suggested. 



The beet nematode, L. Fulmek (Monatsh. La/idio., Jf (1911), No. 9, pp. 

 268-275, figs. 8; abs. in Coitbl. Bakt. [etc.], 2. Abt., 32 (1912), No. 6-12, p. 

 31 Jf). — This parasite was studied chiefly in its relation to the sugar beet. Its 

 life history is discussed, also direct and indirect methods of combating its 

 ravages, which also extend to several other cultivated plants. The develop- 

 ment period is said to depend largely upon temperature. 



Recommendations are made as to economical means for control of the dis- 

 ease, mainly along the following lines: (1) Rotation of crops so that no two 

 which are favorable to the i^est shall be planted within 4 years, (2) care- 

 ful adaptation of fertilizers to soils, (3) shallower plowing, (4) avoidance of 

 carrying infection by feet or tools, (5) removal of harboring weeds, and (6) 

 the Kiihn device of trap plants. 



Further notes on the sooty mold of tobacco, B. Inglese (Bol. Tec. Coltiv. 

 Tabacchi [IScafati], 10 (1911), No. 5, pp. 255-267; abs. m Intcniat. Inst. Agr. 

 [Ro7ne], Bui. Bui\ Agr. Intel, and Plant Diseases, 3 (1912), No. 1, pp. 308, 



