52 Report of the Director. 



copper sulphate and paint over with some heavy paint. Actively 

 spreading cankers ma}' be checked by simply cutting out the diseased 

 bark and allowing the wound to dry. It should be painted later to 

 prevent the entrance of rot fungi. 



h. Cultivation increases the susceptibility of apple trees to this 

 disease. 



i. Certain varieties are more susceptible than others. Only one 

 was found that was entirely immune, that was the Wolf River. 

 Talman Sweets are quite resistant. Baldwins and Ben Davis are 

 most susceptible and the first to go out. 



While the cause of this disease seems to be well established, there 

 still remains much important work to be done in the way of verifjdng 

 certain conclusions by more extended observations, the duplicating of 

 some of the inoculations, the determination of conditions most favor- 

 able to the development of this disease on the bodies of the trees, 

 susceptibility of varieties, relation to "collar rot," etc., and the 

 relation of certain phenomena, such as, bleeding, etc., to this disease. 

 A continuation of the work along these lines is planned for next year. 

 It is also planned to undertake some investigations into the means 

 by which this disease is disseminated to the twigs and water sjjrouts 

 resulting in twig blight. 



2. Diseases of Ginseng. — This investigation is a continuation of 

 the work begun by Mr. Van Hook in 1903. Practically all our work 

 along this line during the past season has been devoted to a study of 

 the leaf blight of ginseng. 



Leaf Blight. — This disease is by far the most widespread with 

 which the grower has to contend. The past rainy season has been 

 especially favorable to its development, and losses from it have been 

 heavy. It is due to a fungus, Alternaria. It attacks stem, leaves 

 and fruit. In most cases it completely destroys the parts of the 

 plants above ground. The roots are not affected and aside from a 

 reduction in growth do not seem to suffer. They send up apparently 

 as healthy stalks the year following a severe attack of the disease as 

 they do following a year in which the tops have not gone down. The 

 disease almost always ruins the seed crop. It is quite destructive 

 to the foliage of seedlings, greatly reducing root growth. It is 

 largely responsible for the "blasting" of seed even though the foliage 

 ma}'' not suffer much. It has been demonstrated beyond question 

 during the past season that it may be controlled entirely by the 

 proper use of Bordeaux mixture. The disease was found on wild 

 plants. 



