328 STATE HORTICULTURAL SOCIETY. 



If arsenites are used with the fungicide, as they should be for at least 

 two applications, the trees should not be sprayed while in bloom, on 

 account of the danger of poisoning the bees. After careful experiments 

 for three years, we are convinced that we must look to the copper com- 

 pounds for our remedies, but we have been able to find but little difference 

 in the effects produced by the various standard mixtures, and, in selecting 

 the kinds to use, would be guided by the relative cheapness and the ease 

 of preparing and applying. 



PEAR BLIGHT. 



This dreaded disease is due to the presence in the tissues of a minute 

 germ, known as Micrococcus amylovorus — Burr. They enter through the 

 stigmas and nectaries of the flowers, through the soft tissues of the newly 

 formed leaves and stems, or through wounds or cracks in the bark. The 

 pear Phytoptus also seems to greatly increase the spread of the disease. 



The character of the variety seems to have much to do with the liability 

 of the trees to attack, as varieties that grow rapidly and develop soft, 

 watery shoots, are more subject to the blight of the young shoots than 

 those that grow slowly and ripen their shoots as they develop. 



Trees on land rich in organic matter, make a rank growth and are very 

 subject to the disease. Pear trees on light soils, particularly in dry 

 seasons, and when bearing full crops of fruit, are also liable to the attack 

 of the disease on the trunk and lower branches. Under the burning rays 

 of the sun, the tree gives off moisture faster than the roots can take it up 

 from the dry soil; the bark becomes parched, and growth is checked; the 

 trunk keeps on growing and bursts the bark, exposing the live tissues 

 below, and affords a means of access to the germs. When the tree makes 

 a late growth in the fall, the freezing and thawing of winter often crack the 

 bark. From the portion of the tree attacked, and the appearance of the 

 affected portions, various names have been applied to the disease; when 

 the trunks have been cracked by frost it is called frozen sap blight; if they 

 they were ruptured owing to the scalding by the sun's rays, fire blight is 

 the term used; when the new shoots are first attacked, it is often spoken of 

 as twig blight. This form also attacks the apple and quince, but seldom 

 does so much harm to them, while in the pear it frequently extends to the 

 older portions and destroys the tree. 



Whatever the means by which the germs enter the trees, or the forms in 

 which it appears, the disease itself is due to the presence of the microbes, 

 as can be shown by the fact that if a healthy tree is inoculated with sap 

 from a diseased tree, the blight will be developed. 



The first thing to be done as a preventive, is to avoid the conditions that 

 favor the entrance of the germs. Select varieties that make a slow, firm 

 growth; avoid the use of land, for pears, that is unduly rich in organic 

 matter; head low, and so prune as to leave enough branches well down on 

 the trunk, to protect the trunk and main branches from the midday sun; 

 keep the surface soil to the depth of two inches stirred so as to form a soil 

 mulch, or secure the same thing by applying a mulch of straw or marsh 

 hay; assist the tree in maturing its wood by applying mineral fertilizers, 

 such as wood ashes and ground bone. In case blight manifests itself on 

 the branches, they should be cut off well below the point where the dis- 

 ease has appeared. Little or nothing is known concerning the efficacy of 



