482 THE MONTHLY BULLETIN. 



How to Control.— As this disease starts its Avork early in January in 

 California and as spraying in the spring is ordinarily too late for the 

 best results, it is advisable to spray the trees between October 25th and 

 November 25th, in order to destroy the fungus before it can start 

 working upon the winter buds. The spray recommended is Bordeaux 

 mixture, the formula being 30 pounds bluestone and 35 pounds lime 

 to 200 gallons water. 



Pear Blight. 



What the Disease Is. — Pear blight is a bacterial disease. It is more 

 conspicuous in the early part of the season, when it appears in the form 

 of twig blight during the blossoming period on both pears and apples. 

 A few weeks later, after the period of pollination, the blossoms and 

 tips affected begin to wilt and blacken. This results in the complete 

 blackening and death of all affected branches and spurs upon which 

 the flower clusters have been borne. Upon the pear the blight may 

 continue to extend down the twigs into the branches, later from the 

 branches into the larger limbs or into the trunk of the tree. Water 

 shoots are often attacked. The disease is usually indicated by the 

 appearance of the bark: the soft bark presents a water-soaked appear- 

 ance and finally becomes blackened and shriveled. The organistns 

 may, however, extend to a distance of several inches or even a foot 

 helow the water-soaked area. If the disease ceases to spread rapidly 

 there is a line between the dead and the apparently live wood. Some- 

 times the bark becomes broken and a gummy exudation appears. The 

 pear blight bacteria winter over in relatively few affected branches, 

 under conditions where moisture is sufficient and protection is furnished 

 from drying out. 



How to Control. — The essential steps in pear blight control, accord- 

 ing to Duggar,* consist in the following: 



"In pruning out the blight in situations where it may winter 

 over, if the blight could be thoroughly pruned out of the orchard 

 during the fall and winter, there would probably be no oppor- 

 tunity for infection the following season, except from other 

 orchards. In practice the pruning of the blight during the winter 

 is not so easy, as it requires care and the keenest eyesight. It may 

 be necessary to go over the orchard several times. Pruning during 

 the growing season is also practiced, but it is not so effective. This 

 pruning has not proven such a great success, on account of the 

 fact that infection may be contantly taking place. Moreover, when 

 the blight is rapidly extending in the limb or trunk, it is difficult 

 to determine the extent of the region aifected. Carelessness in 

 pruning of nursery stock may actually result in spreading the dis- 

 ease to practically all the trees. The knife should be promptly 

 applied wherever a limb or trunk may be saved. Disinfect both 

 pruning tools and cuts with corrosive sublimate, 1 to 1,000." 



The Brown Rot. 



What the Disease Is, — The brown rot is a fungous disease, which 

 attacks the stone fruits. The fruits are the most susceptible parts of 

 the tree, although in the early spring the flowers and young twigs 



•Fungous Diseases of Plants. 



