36 



Besides the pear, the same disease affects the quince and the apple. 

 The apple is, however, quite resistant and rarely suffers injury. 



The first appearance of the disease is usually after the flowering 

 time. In 1901, owing probably to the cold weather, the disease did 

 not become noticeable till the fruit was fairly well grown. An attacked 

 branch is alwa3^s killed and not rarely the whole tree succumbs. If 

 left alone the disease usually continues to go down the branches during 

 the greater part of the summer. Sooner or later, however, it ceases, 

 and in the fall of the year one will find that in a majoritj'^ of the black- 

 ened limbs, where the leaves cling a long time, there is a well-defined 

 line between the dead blackened part and the healthy bark. On these 

 limbs the disease has died out. On the other limbs, especially water 

 sprouts, it will be found that there is no such line of demarcation, but 

 the diseased portions fade insensibl}" into the healthy ones. On cut- 

 ting into such a branch it is found to be moist, not dry as in the case 

 of the dead limbs. It is in these comparativel}^ few limbs that the 

 blight germ lives over the winter. With the renewed growth in 

 spring it frequently happens that a slimy sap exudes out of these 

 limbs, which is swarming with the germs of the disease. Flies and 

 bees are attracted to the juice, and then flying to the flowers are almost 

 sure to leave in the honey pit some of the germs which have become 

 attached to their beaks or feet. In the hone}" of the flower the germs 

 rapidl}^ multiply, and work thence downward into the twigs. As bees 

 are very abundant on trees in flower it may readily be seen how the 

 disease becomes spread. 



Culture methods. — A peculiar fact about this disease is that it attacks 

 first the most thrift}^ trees; slow-grown stunted trees are less liable to 

 it. This fact has been taken advantage of in blight-infested regions 

 by planting the pear and quince trees in very poor soil, thus insuring 

 slow growth and a consequent partial immunity from the disease. 



In richer lands the pear orchard should not be cultivated. In irri- 

 gated lands no more water should be given the pears than is absolutely 

 necessary. It is well, too, not to prune the trees much, as this tends 

 to force new growth, which is more favorable to the disease. Such 

 methods are of value in the handling of a pear orchard. 



Summer pruning. — In an}'^ case recourse must be had to cutting out 

 the ])light. This should be done as soon as it appears, care being taken 

 to cut off each diseased sprig or branch Avell below the lowest trace of 

 the blight. If the disease has run down a short lateral to a main 

 branch, the latter must be cut off" below the origin of the lateral. If 

 the disease has reached the main trunk the tree is doomed. Ip this 

 pruning it is quite easy to get the knife or the shears covered with the 

 germs and thus spread the disease each time a cut is made. It is there- 

 fore well to dip the knife or shears now and then in a strong solution 

 of carbolic acid, which will destroy any germs that may be on it. 



