31 



THE PEAR-LEAF BLISTER-MITE. 



The presence of this pest is readily known by the bright red pimple- 

 like spots that appear on the young leaves. Later these spots turn 

 green and then brownish, forming cork-like thickenings on the under 

 sides of the leaves. The cause of the spot is a minute four-legged 

 mite, scarcel}^ visible to the naked eye, and measuring l)ut one one- 

 hundred-and-fiftieth of an inch long. Its body is cylindrical in form 

 and marked crosswise b}" numerous fine stria?. As soon as the leaves 

 burst from the buds in spring the mites burrow into them, forming the 

 bright red galls, which are hollow and have minute openings on the 

 under sides of the leaves. In these galls eggs are laid, which soon 

 hatch into young mites. As fast as new leaves come out the mites 

 migrate to them, forming new galls, and this process continues as long 

 as leaves are developed. Before the leaves fall in autumn the mites 

 crawl back to the twigs and pass the winter in cracks in the bark and 

 similar places, but more particularly beneath the scales of the winter 

 buds. At no stage of the mite's life is it able to move fast, but the 

 pest becomes spread from tree to tree by crawling on insects, the feet 

 of birds, and probably in other similar wa3^s. The damage done is 

 sometimes quite severe, as the function of ithe leaves is seriously 

 impaired by their attacks. The affected leaves also fall prematurely. 



Remedies. — Experiments with this pest have not been very satis- 

 factory. Spraying in winter when the mites are under the bud scales 

 with kerosene emulsion diluted only three tinies gave the best results, 

 but this strength also injured the trees somewhat. In no instance were 

 all the mites destroyed. Protracted periods of cold weather are fatal 

 to the pest, and it was almost exterminated in the inland region during 

 the winter of 1898-99. 



BACTERIAL AND FUNGOUS DISEASES. 

 BLACKSPOT APPLE CANKER. 



description. — This disease has been demonstrated by Newton B.' 

 Pierce to be caused by a fungus which has recently been named by 

 Peck, Macrophoma curvispora^ and later b}" Cordley as Malicofticis 

 gloeosporium. As the disease is unknown save in the Coast region 

 of the Northwest, it is in all probability native, though it has not yet 

 been found on wild trees. Apparently it attacks only the apple. 

 Similar but far less serious diseases occur on both the pear and prune. 

 The blackspot disease is confined to the bark, and derives its name 

 from the characteristic dark brownish or nearlj^ black spots which it 

 causes. These spots appear only on smooth bark in which no cork has 

 developed. Hence on old trees they are found only on the branches 

 and twigs, but on 3'oung trees occur everywhere, being usual h- most 



