DISEASES OF PLANTS. 445 



plums to the brown rot fungus, which have been carried on since the spring of 

 1913. The fungus in Minnesota is believed to be identical with that found in 

 other parts of this counti*y and witli Sclcrotinia cinerea in Europe. 



Infection may tal^e phice througli tlie uninjured sliin at any time during the 

 development of the plum fruit. Varieties show variations in resistance to rot 

 after the hyphse have gained entrance to the fruit. Resistance is considered to 

 be correlated with a thick skin, the production of parenchymatous plugs which 

 fill the stomatal cavity, the production of corky walls in the lining cells of the 

 stomatal cavity, and firmness of fruit after ripening. No relationship was 

 observed between the oxidase content of the fruit and resistance, or between 

 tannin content and resistance. 



The brown rot is said to be essentially a ripe rot, affecting the plums most 

 noticeably as soon as they begin to soften as a result of ripening, due to the 

 solution of the middle lamella. Varieties which are resistant remain firm on 

 ripening. The hyphre of the fungus are said to be entirely intercellular. All 

 attempts to demonstrate the presence of an enzym capable of dissolving the 

 middle lamella or to extract it from a culture of the fungus in apple cider 

 proved futile. 



The rot caused by S. cinerea is a firm rot, due to the mechanical support of the 

 hyphse which completely fill the intercellular spaces left by the collapse of the 

 host cell walls. A soft rot is produced by Penicillium expansum, which does not 

 produce extensive hyphse and therefore does not give mechanical support to the 

 rotted tissue. 



A bibliography of literature cited is given. 



Experimental spraying' for blackberry anthracnose in 1915, H. L. Rees 

 (Washington Sta., West. Wash. Sta., Mo. Bui., 3 (1915), No. 8, pp. 2-10, figs. 

 If). — Continuing previous work (E. S. R., 33, p. 54), the results are given of 

 experiments for the control of blackberry anthracnose in western Washington. 



It was found that the disease can be successfully and profitably controlled by 

 two sprayings, the first just before flowering, using Bordeaux mixture 5 : 5 : 50, 

 the second 2 or 3 weeks after the petals have fallen, Burgundy mixture being 

 employed. The author states that neither cutting out the canes nor spraying in 

 the fall is necessary for the control of anthracnose. 



Attention is called to the fact that much of the loss is due to the dying of 

 canes through inadequate drainage and insufficient plant food. 



Formulas for the preparation of the fungicides are given. It is recommended 

 that resin fish oil soap, at the rate of 1 lb. to 50 gal. of spray, be added to secure 

 better distribution and greater adhesiveness of the mixtures. 



Observations relative to an obscure grape afiEection, F. E. Gladwin {Phyto- 

 pathology, 5 (1015), No. 3, pp. 169-174, fig. i).— The author states that his 

 attention was attracted in 1910 to a sickly appearance of the leaves of Concord 

 grapes in a young vineyard. In 1911 and 1912 the disease was reported in the 

 same vineyard and also in some where the vines had been set for a considerably 

 longer time. Except in the oldest vineyards, the same conditions appeared in 

 1913 and 1914. 



During the dormant season there are no evidences of the trouble, but early in 

 July the upper leaves of the shoots show a streaked yellow between the veins. 

 Later other leaves on the shoots develop a pale discoloration, which is more 

 marked near the margin of the leaf. As the season advances, the tissues dry 

 and become functionless. The infected vines produce few shoots, the fruit is 

 abnormal, and the woody growth materially checked. 



No fungus or other organism could be definitely associated with the trouble, 

 but a study made of the soil indicated that the disease was due to a lack of 



