416 SUMMARY OF cui;u1':nt keseaughes relating to 



that at the time of thinning the trees contain a large amount of suitable 

 food material for the fungus in the form of soft rubber wood, and it 

 therefore follows that the thinning-out stage is the most dangerous one 

 in the life of the plantation. 



Takewo Hemmi * has written a full account of a die-back disease of 

 Pauloivnia tomentosa caused by a fungus, Valsa Pauloivnise Miyabe & 

 Hemmi sp. n. It attacks branches and trunks of the tree at any age, 

 though young trees are most liable to disease ; the bark turns brown, 

 and the area of disease gradually extends. After the stem is dead, the 

 fructili cations of the Valsa appear : first a small black stroma con- 

 taining the pycnidia, later the ascosporous stage. The fungus grows 

 well on cultures, though the ascosporous stage is more difficult to 

 reproduce. 



A root-rot fungus from Texas, which has only been found so far in 

 the couidial stage, has been described tentatively by B. M. Duggar f as 

 Pli'l/matotriclium omnlvorum. Such various host-plants are enumerated 

 as Ulmus, Moms, Ficus, Acer, Tilia, Gydonia, Eobinia, Prumis, etc., 

 though the disease was first known as cotton-blight, and was described as 

 Ozonium omnivorum. The plants are attacked at the root, and very 

 quickly die off. The hyphse invest the roots with a weft of small 

 strands, and these strands may spread for a long distance through the 

 soil ; they are colourless, or pale-buff, when young, becoming brown 

 when old. The different growth stages and the fructification are 

 described, and a bibliography of works bearing on the subject is 

 appended. 



J. C. Gilman* has published an account of the relation of tempera- 

 ture to the occurrence of the disease known as Cabbage Yellows, which 

 is caused by the fungus Fusarium conglutinans. This is a facultative 

 parasite living in the soil, and, under certain conditions, becomes 

 destructive to cabbage, causing the yellowing and finally the falling-off 

 of the leaves by the formation of an abscission-layer. The disease is 

 most active between the temperatures 17-22° C. Lower temperatures 

 prevented the occurrence of the disease in controlled areas. A large 

 bibliography of works bearing on the question is given. 



In a contribution concerning silver-scurf on potatoes it is stated by 

 J. J. Taubenhaus § that (1) it has been proved that Sponylodadlwn 

 atrovirens Harz is the cause of the disease ; (2) that it is only a skin- 

 disease, and is carried with the seed and soil. Another fungus, recorded 

 variously as PheJlomyces scUroUophorus, Vennicularia atramentaria, and 

 C'oUetot rich urn solanicolum, but, Ijy rules of priority, to be now known 

 as CoUeiotrichum atramentarium, is entirely unconnected with Spoadijlo- 

 chuUam ; it is apparently a saprophyte, or at best a very weak parasite, 

 and, though frequently found on the spots caused by silver-scurf, is 

 merely a secondary invader. Silver-scurf itself does not produce scab 

 or rot ; when such symptoms accompany its appearance, they are due to 

 Fusaria or other funo-i. 



o 



* Bot. Mag. Tokyo, xxx. (1916) pp. 304-15 (4 figs.). 



t Ann. Miss. Bot. Gard., iii. (1916) pp. 11-23 (5 figs.). 



X Ann. Miss. Bot. Gard., iii. (1916) pp. 25-84 (2 pis. and 21 figs.). 



§ Mem.N.Y. Bet. Gard., vi. (1916) pp. 549-60 (3 pis.). 



