Diseases of the Plum 331 



It is seldom destructive on plums, however. Not a 

 single serious case of its work has come to the 

 knowledge of the writer. The powdery mildew can be 

 easily controlled by spraying with fungicides. 



Lichens sometimes appear on plum trees in quan- 

 tity, especially in the southern states. They are un- 

 sightly, but whether they do any direct damage or not 

 is an open question. Bordeaux mixture will keep 

 trees free from lichens. 



Sunscald. — Plum trees are subject to sunscald, to 

 just the same extent that other fruit trees are, and no 

 more. Sunscald is a very serious matter in some parts 

 of the country, especially in the southwestern states. 

 The danger from sunburning is well understood by 

 orchardists in that country, and well-studied precau- 

 tions are taken to avoid damage. In some other sec- 

 tions of the country the seriousness of sunscalding is 

 not fully appreciated; and many trees are lost which 

 might have been saved by a little foresight. The scald 

 is especially disastrous when, as sometimes happens, 

 it is followed by borers. In fact, the scalding of a tree 

 leaves the way open for the attack of all sorts 

 of parasites. 



Sunscald is worse on dry, sandy land, and on 

 southwestern exposures. It is most prevalent in the 

 southern and southwestern states, where, in some 

 places, it may fairly be counted the orchardists' worst 

 enemy. 



The precautions to be exercised against sunscald 

 are good cultivation and low heading of the trees. The 

 latter is the more obviously important, and is always 

 properly recommended. Gcfod cultivation is more im- 

 portant as a protection from sunscald than is usually 

 supposed. The scalding does not come chiefly from 

 the direct action of the sun, but rather more from the 



