DISEASES OF PLANTS. 845 



on certain soft tuber rots of G. colviUi and /. maculata, are said to sliow that 

 these are produced by two bacteria claimed to be new and uarued Pseudumonas 

 gladioli and Bacillus ixiw, which also proved able to produce disease on other 

 plants. Conditions indispensable to the progress of the disease after infection 

 are a temperature of 25 to 30° C. and a high degree of humidity. 



The enzymatic activity of two bacteria pathogenic to plants, G. Seveeini 

 {Ann. Bot. {Romc^, 11 (1913). No. 3, pp. ^.'f 1-^52). —As a result of further 

 study of Pseudomonas gladioli and Bacillus twice (see above) the author states 

 that both these produce pectinase, showing about equal activity in each case. 

 It is claimed also that invertase, amylodextrinase, and maltase are produced by 

 both, but much more abundantly by B. ixiw. P. gladioli produces proteolytic 

 enzyms which long retain their activity. 



Annual report for 1912 of the botanist, R. H. Biffen {Jour. Roy. Agr. Sac. 

 England, 73 {1912), pp. 284-2S9). — In addition to a report of the results of seed 

 testing work, the author gives an account of a number of diseases observed on 

 various economic plants. 



Serious injury following the spraying of potatoes with a mixture of 8 lbs. of 

 copper sulphate and 10 lbs. of sal soda in 40 gal. of water led the author to 

 conduct some experiments to test the effect of a fungicide of this strength. 

 The treated plants became yellow and were partially defoliated. Later leaves 

 were put forth that were quickly attacked by the fungus Phytophthora infestans. 



Brief notes are given on the occurrence on specimens of sainfoin and alfalfa 

 of sclerotla similar to those produced by Sclerotinia trifoliorum. The possibility 

 of controlling this fungus with the application of fresh lime is being tested on a 

 large scale and spraying with fungicides on a smaller scale. 



Considerable loss to wheat and other cereals is reported as due to rust, mil- 

 dew, smut, and also attacks of Scptoria graminis and CladospoHum herbanon. 

 Helminthos-porium gramincum on barley is reported, and it is said that injury 

 may be prevented by soaking the seed in a dilute solution of formalin for 5 or 

 10 minutes. 



The occurrence of silver leaf on Victoria plums, apple trees, and laurel is 

 reported, and as curative measures are said to be unsatisfactory the destruction 

 of the trees is recommended. Specimens of an obscure disease, popularly known 

 as leaf scorch of the apple, were received from a number of fruit growing dis- 

 tricts, but all attempts to find a fungus capable of causing the disease have 

 failed. 



Beport of the Hohenheim. Institute for Plant Protection, 1912, O. Kirch- 

 NER {Wiirltemb. Wchnbl. Landxo., 1913. Nos. 29, Bcihige, pp. 439-U2; 30, 

 Beilage, pp. 455-457). — This is a condensed account of some investigations made 

 during the year on the nature, progress, prevention, and treatment of numerous 

 pests and diseases affecting grains, grasses, vegetables, fruits, vine.s, ornamental 

 plants, etc. 



Field experiments with flag smut, 11. W. Peacock {Agr. Gaz. lY. S. Wales, 

 24 {1913), No. 5, pp. 3S1-3S4). — This disease, due to Urocystis triiici, is said to 

 be gradually spreading each year in New South Wales and to be seriously 

 interfering with the quantity of wheat produced. It is estimated that in 

 parts of Australia as much as 50 per cent of the crop has been lost la this way. 

 This first year's experimentation, admittedly tentative, but fairly consistent in 

 the two plantings, apparently shows that treatment with copper sulphate and 

 lime water is effective in destroying the spores on infected seed grain, but that 

 the presence of diseased parts of plants plowed under may prove a source of 

 infection even when the seed has been treated. The use of stable manure was 

 followed by tafection, but this result was not regarded as conclusive. 



