396 SUMMARY OF CURRENT RESEARCHES RELATING TO 



In the United States* chestnuts have suffered severe damage from 

 Armillaria mellea. The effect on the trees is shown in the large Dumber 

 of diseased beads, in the drying of the tips of the branches, and in the 

 ultimate destruction of the trees. The prevalence of Armillaria in 



S. Carolina is one of the factors responsible for the gradual disappear- 

 ance of the chestnut from that State. 



In discussing diseases of potatoes 0. Appel t cites several that are due 

 to microfungi. A number of these, termed leaf -roll diseases, he prefers 

 to designate as vascular mycosis, as the vascular tissues are browned by 

 the disease. The fungus causing the disease may be a Fusarium, but 

 Verticillium also causes a similar disease. Vascular mycosis in America 

 is especially prevalent in irrigated districts. 



Other diseases are the "foot-diseases." One of these is caused by 

 Rhizoctonia, which attacks seedlings. It also retards growth of older 

 plants, so that the haulms are shorter than usual. In a bad attack the 

 whole shoot dies. As the fungus is in the soil it is not of much avail to 

 sterilize the seed tubers. More study of soil conditions is required. 

 Another disease caused by a fungus, probably Fusarium. caused the 

 blackening of the stem. The primary vessels were filled with the hyphae 

 of the fungus. 



E. E. Hubert | found that galls on the twigs of Populus tricho- 

 carpa were masses of pycnidia of a new Macrophoma, which has been 

 named by C. L. Shear M. tumsefaciens. A diagnosis of the fungus 

 is given. The galls almost invariably appear " at the point where twigs 

 and branches fork." The twigs and branches are frequently killed by 

 the fungus. 



Faith Fyles§ publishes an account of the ergot of wild rice (Zizania 

 aquatica and Z. palustris). Experiments were made by inoculation on a 

 series of grasses other than Zizania, with negative results. Further 

 work is promised. 



Lichens. 



(By A. Loreain Smith, F.L.S.) 



Development of the Ascogonium in Peltigera. || — Fernand 

 Moreau and wife have published an account of their research, on 

 the development of the ascogonium in the genus Peltigera. It orig- 

 inates from the hyphae of the medulla at the edge of the fertile 

 lobes of the thallus, and at first consists of hyphae larger than those of 

 the surrounding tissue, which are at first uninucleate, but by nuclear 

 division become multi-nucleate. At the same time the protoplasm 

 becomes denser and more chromatic. Very soon the cells of the asco- 

 gonium send out multi-nucleate ascogonial hyphae ; these branch and 

 cut off at their tips a series of bi-nucleate cells. These terminal cells 



* Bull. U.S. Dept. Agric, No. 89 (1914) pp. 1-9 (2 pis.). See also Bull. 

 Agric. Intell. Rome, vi. (1915) p. 472. 

 + Phytopath., v. (1915) pp. 139-48. 

 X Phytopath., v. (1915) pp. 182-5 (3 figs.). 

 § Phytopath. v. (1915) pp. 186-91. 

 . Comptes Rcndus, clx. (1915) pp. 526-8. 



