644 EXPERIMENT STATION RECORD. [Vol 40 



As a result of laboratory and field experiments, it has been determined that 

 the disease can be carried with infected sets or from year to year in the soil. 

 Steam sterilization or sterilization with formaldehyde will kill the organism in 

 the soil. In addition to onions, garlic and shallot are subject to attack, but 

 the organism does not seem to attack any other liliaceous plants. It has been 

 found that by the liberal use of fertilizers growth may be so stimulated that 

 new roots are produced more rapidly than the disease can destroy them. 



The growth of the potato scab organism at various hydrogen ion concentra- 

 tions as related to the comparative freedom of acid soils from the potato scab, 

 L. J. Gillespie (Phytopathology. 8 (1918), No. 6, pp. 257-269, fig. 1).— In order to 

 ascertain a reason for the freedom from Bcab in potatoes grown on acid soils, 

 the author carried on experiments to determine what intensity of acidity is 

 inimical to the growth of Actinomyces ehromogemm in culture media. A num- 

 ber of strains of the organism were studied in relation to various hydrogen 

 ion exponents, different media being employed. 



In media at an exponent of Ek2 growth was slower and generally less vigorous 

 than at less acid exponents. Under some conditions individual strains were 

 somewhat more sensitive to acidity, but the differences did not lead to any 

 consistent distinctions among the strains. Sometimes the strains succeeded 

 in growing well in a medium which had initially an exponent of 5.2 or even 

 4.8, but the growth was accompanied by a marked decrease of acidity. From 

 his Investigations the author concludes that the acidity of the Caribou loam 

 soil, which is known to he generally immune from the common scab of the 

 potato, is often of sufficient Intensity to exert to th^ soil an injurious action 

 on the causal organism. 



A new disease of the Irish potato. C. YV. CAXFKRTO (l'h\it<>i>a1h<>U>g)i, 8 

 (1918), No. 6. i>y 286-288, i>l. />.— A disease of the Irish potato occurring in 

 Hawaii and considered new to pathologist- is described. The disease, which 

 appears to be due to mites, is characterized by the bronzing and twisting of 

 the young terminal and axillary leaves. Later the leaves and shoots become 

 abnormal and soon dry up and die. The author states that with averge rainfall 

 in potato sections mites do not appear troublesome, but in the dry periods 

 losses estimated at as much as 50 per cent have been reported. Spraying with 

 lime-sulphur or dusting with dry sulphur has been found an effective means 

 of control. 



Blossom drop of tomatoes. 1". M. EtoUS (Oklahoma Sta. Rpfc, 1918, pp. 40- 

 43). — A progress report is given on investigations carried out to determine the 

 cause of blossom drop of tomatoes in Oklahoma and methods for its control. 

 In the period covered by the report, cultivation, irrigation, mulching, slaking, 

 and pruning were tested. 



The application of water produced more vigorous vegetative growth, the fruit 

 from this plat being smoother and better In appearance though the yield was 

 not increased over that of the check plats. In culture and pruning experiments 

 the use of a V-shaped trellis seemed to give somewhat larger yields, although 

 the fruit of plants which were staked and pruned was earlier and larger. The 

 development of Individual blossom clusters was noticeably stimulated by prun- 

 ing. Tests of varieties were made, but no apparent differences in 36 varieties 

 were noted, the yields from all being very low. 



Dissemination of Septoria lycopersici by insects and pickers. W. EL Martin 

 ( I'liytojiatliology, S {1918), No. 7. pp. 365-372).— In connection with experiments 

 conducted in the summer of P.U7 for the control of the tomato leaf spot, studies 

 were made to determine the possibility of dissemination by Insects and pickers. 

 The author reports that in New Jersey the tomato is visited by Colorado potato 



