246 EXPEEIMENT STATION EECOED. 



myces chromogenus. Several strongly pathogenic strains were studied at tlie 

 Maine Experiment Station after being isolated from diseased specimens from 

 Maine, Vermont, and Wisconsin. 



It is stated that while temperatures of 35 to 40° C. are most favorable for 

 germination of the gonidia, they are unfavorable for long continued growth, 

 although at 35° a stimulating effect was produced at first. The maximum 

 temperature for growth is about 40.5°, the optimum 25 to 30°, and the minimum 

 about 5°. 



Involution forms appeared abundantly when 0.25 per cent of potassium mono- 

 phosphate was included in a synthetic culture medium, but none resulted from 

 temperature conditions. 



The use of sulphur for the control of potato scab, H. C. Lint (Abs. in 

 Phytopathology, 4 (1914), No. 6, pp. S96, 397). — Investigations have been car- 

 ried on to obtain data regarding the effectiveness of sulphur for the control of 

 potato scab, and also to determine the influence of the various factors involved. 



The results thus far obtained indicate that spring applications are more satis- 

 factory than fall applications. The benefits derived from the use of sulphur 

 were greater when applied to land on which no cover crop had been grown the 

 preceding season than on land where such a crop had been used. Seed treat- 

 ment with formaldehyde and the application of sulphur to the soil gave better 

 results than the sum of these two treatments used separately. Broadcasting of 

 the sulphur on the soil after planting is considered the best method of appli- 

 cation. When used in connection with fertilizers, sulphur was found more 

 effective with ammonium sulphate than with sodium nitrate, with acid phos- 

 phate than with steamed bone, and with muriate than with sulphate of potash. 



Seedling diseases of sugar beets and their relation to root rot and crown 

 rot, H. A. Edson {U. 8.*Dcpt. Agr., Jour. Agr. Research, 4 (1915), No. 2, pp. 

 135-16S, pis. 11). — ^A study is reported of damping off in beets, also of another 

 seedling trouble designated as root sickness, together with associated rots of 

 the growing or of the mature root. Some factors influencing the health of the 

 plants, as alkali injury, are also discussed. 



Four fungi casually related to damping off are Phoma hetw, Rhizoctonia sp., 

 thought to be identical with Corticium vagum solani, Pythiiim deharyanum, and 

 an undescribed member of the Saprolegneacese. While plants attacked by the 

 first two may recover temporarily or permanently, those suffering from the other 

 two usually succumb. Phoma and Rhizoctonia produce a characteristic decay 

 in mature beets, the former infecting primarily the seedling and remaining after 

 recovery in a dormant condition on the host, developing occasionally a charac- 

 teristic black rot on growing beets in the field, and being noted frequently on 

 beets in storage. It may destroy the root or appear on the seed stalk and the 

 mature seed. 



Control measures are to be sought in proper cultural methods and seed treat- 

 ment looking to the production of uninfected seed. 



P. deharyanum is capable of attacking the feeding roots of the beet throughout 

 its vegetative period, and may attack the mature beets. 



Rhizopus'iiigricans is found to attack the tissue of dead or dormant sugar 

 beets, producing a characteristic decay. 



A bibliography of cited literature is appended. 



Phoma betas on the leaves of the sugar beet, Venus W. Pool and M. B. 

 McKay (J7. S. Dept. Agr., Jour. Agr. Research, 4 {1915), No. 2, pp. 169-178, pi. 

 1). — ^The authors found that P. hetw produces a characteristic infection on leaves 

 that have a stomatal count of CO to 100 per square millimeter on the upper 

 leaf surface, a low physiological condition permitting infection of all except the 



