i:'-"l DISEASES OF PLANTS. 153 



l'';inii. WCrrilicc. I)ala obtiiiiiod Iruiii ntic yciir's study iiitliciitc^ lliiit iiii 

 iilU.-iliiu' soil favors the (Icvi'lopim'iit (if tlie (ils«'ase. An afcduut is f.'ivcii 

 i)f I lie system of rotation followed in the {^reeii luanurial plats and the per- 

 centaf^e of disease ohserved in tlie various wheat crops {;''<>wn diirinj^ 11)18. 

 A list of hosts of the fiin^is is jriven ; also an account of rainfall at this 

 ])oiMl, which si'enis to he connected with the development of this disease. 



The bacterial blight of beans, K. M. Doiikik {So. African Jour. ,SV/., 7J 

 (mill). No. 7, pp. 50.i-i)05). — Investigations following numerous complaints of 

 a di.scoloriition and malformation of tield beans showi-d the trouble to be due 

 to an organism apparently identical with Bacterium phaseoli. 



Diseases of celery, W. S. Krout {New Jersey Klan. Circ. 112 {1919), pp. 12, 

 fills. 7). — I'opniar notes are given on different diseases of celery, together with 

 suggesti(»ns on methods of control. These include sanitation, proper culture, 

 seetl bed and soil sterilization, and spraying. As a result of spraying experi- 

 ments conducted by the author, a net profit of .$324 per acre is reported. 



K.vperinients in root rot control, C. R. Lettekr {U. 8. Dept. Ayr., Dept. 

 circ. 73 {1920), pp. 32-34). — In continuation of investigations previously re- 

 ported (E. S. 11., 39, p. 852), the author gives an account of additional «'X- 

 periments at San Antonio, Texas, in soil treatment, mulches, and the effect of 

 excavations for the control of root rot due to Oogonium ou)niroruiii. 



The results in 1918 showed no beneticlal effect of the acid phosphate treat- 

 ment in reducing root rot infection, and the application of oat straw and coarse 

 manure and other mulches was without effect on the spread of root rot, the 

 disease being fully as ijrevalent on the mulched areas as on adjacent land. In 

 order to determine the depth at w'hich the root rot infection takes place, ex- 

 cavations were made 18, 32, and 48 in. in depth in a field badly infected with 

 root rot. From some of these holes the soil was hauled away and the holes 

 fdled with fresh soil from fields which had not been cropped in several years, 

 while from others the soil was thrown out, allowed to remain a few days, 

 and returned to the holes in nearly the same order as before. Cotton was 

 again planted in the fields including the excavated areas, and the results in- 

 dicate that the root rot is in the soil and is removed with the soil. 



Onion smut, R. E. Vaughan and J. C. Walkeb {Wis. Hort., 10 {1920), No. 8, 

 pp. 133, 1//5, fiy-s. 2). — Onion snmt is said to cause losses in Wisconsin amount- 

 ing in some fields to more than .50 per cent. Onion plants with four or five 

 leaves are much more resistant than are those which are just starting. The 

 formaldehyde treatment is said to be effective if properly applied to the seed. 

 Treatment during 191.3-1918 gave increased results, averaging 328 bu. per 

 acre. Directions are given for the preparation and application of the remedy. 



Resistance of potato tubers to scab, B. F. Lutman {Vermont Sta. Bnl. 215 

 {1919), pp. 3-30, pis. 5). — In a study on the potato scab, the author has investi- 

 gated the resistance of varieties to attack. Repeated plantings made between 

 1914 and 1917 on the same soil showed that the percentage of scab in(reas4's 

 even if no manure or lime is added to the soil. Marked resistance to scab was 

 found in the true russet types of tubers. The semirusset types showed some 

 scab resistance, while the white, thin-skinned varieties appeared to be most 

 susceptible. 



In order to determine the reason for the resistance on the part of the russet 

 types, a study was made of the relation of thickness of skin of potato tubers 

 to their resi.stance to scab. It was found that the thickne.ss of skin determines 

 the resistance of the tubers to scab, while color plays no role in the resistance. 

 All russet varieties appeared at least moderat«>Iy resistant. The application 

 of fertilizers and chemicals was found to affect to some extent the amount of 



