DISEASES OF PLANTS. 589 



During the latter part of April the author's attention was called to a milky fluid 

 which was exuding from blighted limbs of pear trees. This fluid was examined and 

 found to be swarming with bacteria. In order to test its virulence dilutions were 

 made of some of this fluid and applied with a camel's-hair brush to pear blossoms. 

 As a result the terminal growth of all shoots whose blossoms were inoculated showed 

 the blight. The organism was separated, grown in pure cultures, and inoculation 

 experiments conducted, in one of which the blight extended down the shoots 14 in. 

 in 4 weeks. In another instance the diseased tissue was observed for 24 in. on the 

 shoot, and all the leaves were blackened. Inoculations made on jjear leaves showed 

 that they were easily infected. 



A peculiar blight of red and black currants was observed that was found to be due 

 to some sterile fungus. The blight may show itself at any point on a live cane as a 

 black discoloration of the bark around a spur. The cause of this disease is believed 

 to be the same as that described in New York State Station Bulletin 167 (E. S. R., 

 12, p. 154). As remedial treatment the author suggests cutting out and burning all 

 blighted canes and protecting the healthy ones by a thorough spraying with Bordeaux 

 mixture. 



A blight of Japanese chestnuts was investigated in which the cause was determined 

 as a species of Cytospora, possibly C. ceratophora. All attempts to produce the dis- 

 ease by inoculation with spores have thus far been unsuccessful. A similar disease 

 was observed on newly set peach trees, and inoculations made with masses of spores 

 resulted in the destruction of the wood about the point of inoculation, but there was 

 no marked spread from that i:)lace. 



The experiments in the spraying of tomatoes for blight were performed on a plat 

 of about one-fourth acre, the vines being given 2 applications of a 6 : 6 : 50 solution of 

 Bordeaux mixture. The sprayed plants seemed fresher and freer from blight than 

 the untreated ones, but the amount of disease on the unsprayed j^lants was so slight 

 that little commercial benefit would have arisen from such an experiment. 



Letters on the diseases of plants, N. A. Cobb {Agr. Gaz. New South Wales, 14 

 {1903), No. 8, ijp. 681-712, pi. 1, figs. 26). — Notes are given on banana scab, stigmo- 

 nose, moldy core of apple, and quince rot. 



The banana scab, which is described at considerable length, affects the fruit, render- 

 ing it unsightly and seriously impairing its quality. The author has separated a 

 fungus which he believes to be the cause of the scab, but has not yet determined its 

 botanical relationship. The banana scab can be prevented by spraying the plants 

 with Bordeaux mixture, but care must be exercised not to discolor the fruit by the 

 adherence of the fungicides. In addition to occurring on the bananas in Australia a 

 scab disease of bananas from the Fiji Islands is reported. 



The stigmonose disease described was due to insect punctures and is said to seri- 

 ously affect apples and pears in Australia, rendering fruit of certain varieties iin^ightly 

 and almost worthless. A shot-hole effect is produced on apricot leaves by attacks of 

 several species of thrips, and the author has described this disease as the shot-hole 

 stigmonose of apricot leaves. 



The moldy core of apples is described as due to attacks of certain molds f)n a fruit, 

 entrance being secured through the calyx end of the apple. Different varieties of 

 apple are unequally affected, and a list is given of a number of species indicating 

 their liability to infection. 



The paper concludes with a brief description of (piince rots caused l)y species of 

 Alternaria. 



A guide to fungus parasites, H. Yandekvst {licv. Gen. Agron. [Loiivalii], 12 

 {1903), No. 9, pp. 3.58-36S). — The present paj^er gives in condensed form descriptions 

 of the Ustilaginea.', their characteristics, distribution in Belgium and elsewhere, host 

 plants, and notes on their economic importance. About 20 species are enumerated. 



Some injurious milde-ws on cultivated plants in German East Africa, P. 

 Hennings {Notizbl. K. Bot. Garten u. Mm., Berlin, 4 {1903), No. 32, pp. 80-82).— 



