DISK ASKS OF PLANTS. ( .tS. r ) 



An accounl of the cause and prevention of pear blight, by M. 15. Waite, is given, 



the article being dopied from the Yearl k of this Department for 1895 E. S I;.. 



s, p. 796). The bulletin concludes with a brief accounl of the leaf blighl of pear and 

 qwince, caused by the fungus EhUomosporium maculatum. 



A new disease of olives, A. Mau blanc /.'"/. Soc. \tycol. France, .'" {1904), rr- 

 figs. 7; abs. in /:<>/. CentbL, 98 (1905), No. 12, p. 299). \ brief accounl is 

 given of a disease of olives due t.> Wacrophoma dalmatica. This fungus forms its 

 pycnidia in brown spots on the surface of the fruit, which extend t . . the center, 

 resembling in a way the puncture <>i insects. The fruil in the process of its develop- 

 ment is 'laic- these diseased areas by forming al »< >ut them ;i corky layer. 



Some causes of the destruction of vines in Tunis, L. k\\ \/ /.'"/. Agr. 

 Algeru <t Tunisie, 11 (1905), No. /•''./'/'. f&4 443). A report isgiven of the investi- 

 gations of a commission appointed to determine the cause of the rapid destruction of 

 grape\ ines over quite an extended area in Tunis. 



Studies made in the vineyard and laboratory failed to -how the presence of any 

 fungus or other organism, and the author finally concluded that the trouble \\m- 

 chiefly due to the heavy overbearing of young vines, and the history of a Dumber of 



vineyards tended to confirm this conclusion. Under the condition of grape grovi itr_' 



m Tunis :; and A year old vines produce such abundant crop- that the vines are per- 

 manently weakened and finally die. The author suggests the removal of all dead 

 stocks, replacing them with new ones, and by attention to culture, the use of ferti- 

 lizers, and irrigation during the first few years after planting the losses attributed to 

 this trouble can be avoided. 



Studies on the gray rot of grapes, <h i>i: Istvanffi (Ann. Tmt. Cent. Ampklol. 

 Roy. Hongrois,S\ 1905), No. /,/>/>. 18SS60,pls.8,figs. 15). -The results of an extended 

 series of biological and mycological studies on Botrytis cinerea or Sclerotinia fuckeliana 

 are given. 



Germination experiments are reported upon at length, in which the normal germi- 

 nation of the fungus is described and the effect of various physical agents and chemical 

 compounds si i own. The author gives a general account »f the sclerotia of the fungus, 

 describing their growth on different ['arts of the vine, behavior in pure cultures, etc., 

 as well as practical suggestions for combating the disease, which at times becomes 

 epidemic in its nature. In the studies reported the polymorphism of the fungus is 

 shown and the different forms of growth and reproduction are described. The author 

 bas traced the life cycle of the fungus, adding a number of important discoveries 

 relating to it. 



Among considerations of practical importance in combating the disease, the author 

 Bays that the Botrytis form of the fungus lives saprophytically on fallen leaves, twigs, 

 fruits, etc., "luring the early season, but the conidia develop with great rapidity on 

 the arrival of warm, moist weather, and when transferred to the growing foliage, 

 live parasitically. The Botrytis attacks the ripening fruit in autumn, often causing 

 great loss. Sclerotia are formed abundantly on the grapes and also on the cuttings 



made dining the summer. If the fungus is present upon the cuttings w hen stratified 



the disease will be carried over the winter. The mycelium is also able to pass the 

 winter in the young Bhoots, so care should be exercised in selecting cuttings either 

 for layering or grafting that they are not affected. 



In stratifying cuttings the author recommends wetting the twigs, sand, benches, 

 boxes, etc., with a - r » per cent solution of calcium bisulphid, after which all are to be 

 well dried in the sun before being packed away. In the sprite: of the year the -de- 

 rotia can easily he found on the fallen leaves, twins, dried grapes, etc.. where they 

 germinate about June 1. All debris in vineyards Bhould he coil,, ted and burned in 

 the autumn. Thoroughly washing the vines with a •"> percent solution of calcium 

 bisulphid during late autumn or early spring, and alternate application- during the 

 growing season of I per cut solutions of Bordeaux mixture and powdered sulphur 



