EXPERIMENT STATION REPORTS. 261 



Hot appear. The experience in Wisconsin, however, where similar work 

 was in voj2;ue, demonstrated the practicabiHty of this reconnoisance sys- 

 tem. With wet weather in the first half of the season, Late Blight would 

 have been prevalent, and the warning given would have been most helpful 

 in preventing loss. The full report of Dr. Woodcock's observations on 

 Potato Diseases is to be published in the Twentieth Report of the Michigan 

 Academy of Science. 



A general summary of plant disease conditions of the year has been pre- 

 pared and this is in course of publication in the Twentieth Report of the 

 Michigan Academy of Science. 



The work of the Experiment Station on cucumber diseases under your 

 direct charge, carried on in cooperation with the U. S. Department of 

 Agriculture, is also financed from this fund. Similarly your work in 

 continuation of observations on ginseng diseases is financed from this fund. 



From time to time calls for investigation of various diseases of crop 

 plants come to the Experiment Station. Greenhouse troubles, especially, 

 call for attention. From time to time, workers in the Experiment Station 

 answer these calls and give such. help as the disease conditions warrant. 

 In passing it may be said that the diseases of greenhouse crops are numer- 

 ous and exceedingly important. One of the chief factors governing the 

 success or failure in the greenhouse business is control of plant diseases. 

 It is to be hoped that more attention will be given to the pressing prob- 

 lems confronting the greenhouse industry. 



- STATE POTATO WORK. 



For some years a portion of my time has been devoted to the investiga- 

 tion of potato diseases. A large part of the work done has been to interpret 

 for Michigan conditions the findings of various scientists upon the ex- 

 tremely puzzling and elusive diseases — Mosaic, Curly Dwarf and Leaf 

 Roll. It may be said that due to the facilities afforded by the fund al- 

 lotted to potato work to attend the various conferences of workers on 

 potato diseases, there has been made available to Michigan growers the 

 results of all the research work of plant pathologists in these important 

 and little understood diseases. The observations by Dr. Woodcock have 

 shown that Michigan is in rather fortunate condition in respect to these 

 diseases in comparison with other great potato-producing states. 



Emphasis has again been placed in the potato work upon seed treat- 

 ments for the prevention of Scab, Black-Scurf, and Black Leg. During 

 the war period, the experiments of the Station gave plant pathologists in 

 the various states grounds for great simplification of the methods of 

 potato seed treatments. In place of the rather long period reciuired for 

 soaking potatoes for Scab (13^ hours in formaldehyde, 1 pint to 30 gallons) 

 it was found that 15 minutes was effective. Similarly a 30-minute soak in 

 corrosive sublimate 1-1000, is as effective — and apt to be less injurious to 

 stand — than 1^ or 2-hour soak in the solution. These conclusions, based 

 on ,one year's work are now reinforced with the results of a second year's 

 trials. The full report of these experiments is at present being prepared 

 for publication. 



As a new contribution toward the solution of potato seed treatment 

 problems, the work of last year brought out that mercuric cyanide* 1-1000 



•I am indebted to Mb. Ezra Levin for the suggestion to try marcuric cyanide in this connection. 



