224 SUMMARY OF CURRENT RESEARCHES RELATING TO 



0. A. Pratt ■" calls attention to the frequency of storage-rot in 

 potatoes, in the majority of cases these being due to surface-wounds 

 caused in harvesting. He has investigated the worst of these rots, due 

 to the attack of Fusarium trichothecioides, which produces " powdery 

 dry-rot." It does not attack any part of the growing plant, and as to 

 the tubers it is entirely a wound-parasite. The diseased portion usually, 

 presents a wrinkled sunken appearance, and in advanced stages may 

 show a pinkish-white growth of the fungus. The decayed tissue varies 

 in colour from light brown to nearly black ; internal cavities partially 

 filled with the mycelium and spores of the fungus are frequently found 

 in decayed tubers. The fungus does not develop under 2° C, and in 

 dry well-ventilated storage-houses loss would be very slight. The disease 

 may also be effectively checked by disinfecting the stock with mercuric 

 chloride or formaldehyde, provided the disinfection is done within 

 twenty-four hours of digging. 



J. A. McClintock t has described a disease of peanut (Arackis 

 hypogsea) due to Sclerotium Rolfsii, a fungus that attacks the plants when 

 one to two months old, and continues to develop during the season. The 

 disease shows itself in the wilting of the leaves, while round the shoots 

 at or near the surface of the soil appears, first, the white mycelium, and 

 later the brownish sclerotia, about the size of a mustard -seed. 



C. W. Edgerton % has explained his method of testing disease- 

 resisting varieties of plants in order to secure such plants on the least 

 possible acreage of ground. He experimented with tomato-wilt, a disease 

 due to a Fusarium which lives in the soil. He selected the seed of such 

 plants as had resisted the disease though grown in badly infected soil, 

 and these he subjected also to diseased conditions. A hmited extent of 

 soil was also sterilized and reinfected with tomato-wilt, and the plants 

 were then reared on this soil ; by this method it was possible to collect 

 data as to the varietal resistance to disease, the virulence of the fungi, 

 and the influence of the different soils. 



C. Jagger and V. B. Stewart § have studied the various types of 

 VerticilUum disease in a series of cultures of the fungus from various 

 hosts. They noted in all the ultimate formation of numerous black 

 sclerotia-like bodies. The cultures differed mainly in the rate of growth 

 of these bodies. Experiments were conducted in the field by inocula- 

 tion and by mixing healthy with diseased plants. 



L. M. Massey || records the results obtained in the use of various 

 fungicides. The iiests were made on diseases of roses due to Diplomrpon 

 Rosse (blackspot) and on Sphserotheca pamiosa (powdery mildew). In 

 both cases he found that dusting the bushes with a mixture of ninety 

 parts of finely-ground sulphur and ten parts powdered arsenate of lead 

 was the most effective remedy, and also less unsightly than the sprays 

 generally used, 



F. A. Wolf and E. E. Stanford If describe a disease of fig-trees in 



' " Jouru. Agric. Research, vi. (191G) pp. 817-31. 



t Jouru. Agi-ic. Research, viii. (1917) pp. 441-8 (2 pis.), 

 j Phytopathology, viii. (1918) pp. 5-14 (4 figs.). 

 § Phytopathology, viii. (1918) pp. 15-9. 

 ■ II Phytopathology, viii. (1918) pp. 20-3. 



i Phytopathology, viii. (1918) pp. 24-7 (2 figs.). 



