DISEASES OF PLANTS. 645 



Wtisbiiiii' or .sprayiiii;' will be found iiietiectual, as tlie mycelium bas 

 been traced 00 cm. tVoiu the i)lace where the organs of fructiticatioii 

 are shown. The only treatment is to prevent the spores from gaining 

 access to wonnds and dead wood. For this purjjose the wounds should 

 be covered by some im])crmeable coating, such as coal tar or a mixture 

 of linseed oil, zinc oxid, and lauipblack. The antiseptics mentioned 

 above, tannin and sodium naphtlialate, nuiy be tirst used as a wash 

 before applying the c-oating. 



Weather vs. injurious fungi, B. D. Halsted {Afjl. *S'ci., 8 (1891), JS^o. 

 6-9, pp. 292-297). — The author considers the relatioubetween the weather 

 and the twig blight of fruit trees due to Baoillus amylovorus and a 

 blight of potatoes due to a Vermicularia. 



The twig blight had never been known as prevalent in New Jersey 

 as during the past year. It appears that warm, moist Aveather is con- 

 ducive of ra])id development of the parts of the plant attacked by the 

 fungus and the conditions are offered for a rapid multiplication of the 

 germs within the tender parts of the host. "If this supposition is 

 rational it goes without further discussion that lire blight, while not 

 caused by the weather, is a creature largely of moisture and heat wdieu 

 they come in excess while the fruit trees are unfolding their buds highly 

 charged with the rich elements of stored-up plant food." 



The author thinks that with a knowledge of the relation between 

 weather and fungus development some method of treatment may be 

 found to prevent the blight. 



In the case of the potato blight the vines fail to make normal growth, 

 and when about half sized the leaves begin to turn brown and finally 

 the stems fall to the ground. The crop of tubers will be small ami 

 scarcely worth harvesting. The trouble is usually located near the 

 ground but in bad cases it covers the whole plant, and the fungus 

 causing it thrives under conditions of abundant moisture and warmth. 

 Too much rain will prove injurious to the plants, causing a greatly 

 weakened condition and fittin'g them for the attacks of a fungus not 

 otherwise capable of serious injury to the potato. In this case weather 

 has a very important part in prepari]ig the host for the fungus, and a 

 study of the relation between the two may result in the discovery of 

 the proper time for pieventive application of fungici<les. 



The most important factor in the development of rust, L. II. 

 Pammel {Agl. 8cL,8{1894), No. 6-9, pp. 287-291).— Of the more impor- 

 tant factors potent in causing rust development, namely, climate, 

 character of soil, especially its fertilitj^, and variety of host, the author 

 considers the climate as the most important. Meteorological tables are 

 given showing the rainfall at Ames, Iowa, for the months of May, June, 

 and July, 1800-91, from whicdi it is shown that the amount of rust and 

 precipitation are very closely related, being worse during the years of 

 greatest rainfall. In 1894, -wheu the rainfall was very small, the absence 

 of all fungi was very general. 



