Black Knot of Plums and Cherries. 647 



to be of value. The earlier literature upon the subject contains 

 considerable advice regarding the treatment of the disease, but as 

 its nature was not understood such remedies were founded mostly 

 upon an unreliable basis. For example, it was recommended to 

 dig about the base of the trees in the fall, and to keep chickens ; 

 the use of two or more quarts of salt per tree was considered of 

 value; pulverized blacksmith's cinders scattered about the base 

 of the trees prevented the disease ; iron filings or scraps of old 

 iron answered the same purpose ; much importance was also at- 

 tached to the nature and drainage of the soil in which the trees 

 were growing. This list by no means includes all the sugges- 

 tioras made. 



The preventive measure of cutting out the knots as fast as they 

 appeared was strongly recommended from the earliest time, and 

 this is still one of our best methods, if not the best, of checking 

 the spread of this pest. The best time to do the work is in early 

 spring when the new knots can be seen. This prevents the pro- 

 duction of both crops of spores and will undoubtedly soon rid a 

 neighborhood of the disease if the work is properly done. The 

 next best time is in the fall, before the second crop of spores have 

 matured. If the work is postponed until after these spores have 

 been distributed the value of the operation will be almost entirely 

 lost. From two to three inches of apparently sound wood should 

 be cut away below the knot in order that no part of the fungus 

 will remain in the portion left upon the tree. It has been gen- 

 erally advised to cover the cut surfaces with some material to pre- 

 vent further infection at this point. Shellac, paint, and a solu- 

 tion of copper sulphate have been recommended for the purpose, 

 but the value of the practice has not yet been determined and the 

 labor of covering such surfaces may be very great. When the 

 knots have been removed they should be buried or burned, so that 

 no spores may mature after the operation, as sometimes occurs 

 when the knots are left lying upon the ground. One individual 

 cannot exterminate the fungus in a locality, and if no laws exist de- 

 manding the destruction of the knots, public sentiment should be 

 brought to the point of making such demands. I^aws framed for 

 the purpose of controlling the black knot now exist in Michigan, 



