348 SUMMARY OF CURRENT RESEARCHES RELATING TO 



resting nredospores. Arthur describes a number of species that possess 

 amphispores, nine species in all. 



Potato Diseases.* — F. M. Rolfs has made a careful study of a 

 disease of potatoes caused by Corticivm vagum var. solani. He has 

 established the connection of this fungus with Rhizoctonia, of which it is 

 the fruiting form. There are, therefore, three stages of the disease, the 

 Rhizoctonia, the sclerotial, and the Corticium. The latter usually occurs 

 at the edge of a diseased portion next the living tissues. It bears 

 basidia and spores. Rhizoctonia is a mycelial stage. 



Diseases of Trees.f — 0. Appel has investigated a disease of Red 

 Alder trees. He found dead branches beset with the fruits of Valsa 

 oxystoma. Infection experiments with Valsa spores failed to reproduce 

 the fungus, and the author concludes that the damage is due to several 

 factors, such as frost, failure of water, etc., which render the young trees 

 peculiarly liable to attack from fungi. Other observers have detected 

 several other fungi causing the same disease, Cytosjwra, Meianconium 

 and Cryjrfospora, which attack dry twigs and enter the tissues through 

 wounds. A change of trees is recommended, as also altering the 

 conditions of moisture by draining, etc. 



A. Moller J reports that Trametes Pini causes loss to German foresters 

 yearly of some 1,000,000 marks. He has examined the manner of 

 propagation, and insists on the effort to stamp it out. Pines are safe 

 until the heart-wood is formed, because only in the heart-wood does the 

 fungus develop, infection taking place by a broken branch, and always 

 by means of spores. The spores may be formed during the whole year, 

 but in most abundance from September to January. The mycelium 

 does not live saprophytically. Moller recommends breaking off the 

 fruiting bodies and brushing the base with a preparation of lime. It 

 does not kill the fungus, but it greatly retards spore-production. 



H. C. Schellenberg § writes on the occurrence of Hypodermella Laricis. 

 It attacks the leaves of the lower branches of the Larch more vigorously 

 than those higher on the tree, causing them to turn brown. It does not 

 cause great damage. 



Adolf Aeslar |j gives his views on the cause of Larch disease. The 

 fungus Peziza WiUlcommii is not a pure parasite ; it attacks through 

 wounds or in weakened conditions of the host-plant. 



Plant Diseases in India during 1903.1F — E. J. Butler, Cryptogamic 

 Botanist to the Government of India, records the chief cases of disease 

 that came under his notice. He gives a very short account of the 

 parasite and the host-plant. The most destructive on tea was, he found, 



* Colorado Agric. Exp. Stat. Bull., xci. (1904) pp. 1-33 (5 pis.). See also Bot. 

 Centralbl., xcviii. (1905) pp. 255-6. 



t Naturwiss. Zeitschr. Land. Forstw., ii. (1904) pp. 313-20. See also Aim. 

 Mycol., iii. (1905) p. 111. 



I Zeitschr. Forst. und Jagdw., xxxvi. (1904) pp. C77-715 (2 pis.). See also Bot. 

 Centralbl., xcviii. (1905) pp. 147-8. 



§ Naturwiss. Zeitschr. Land. Forstw., ii. (1904) pp. 330-7. See also Ann. Mycol., 

 iii. (1905) p. 115. 



| Centralbl. Ges. Forstw. (1904) 27 pp. See also Ann. Mycol., iii. (1905) pp. 

 111-12. <J Zeitschr. Pflanzenkr., xv. (1905) pp. 44-8. 



