TWENTY-EIGHTH FRUIT-GROWERS' CONVENTION. 



145 



and we have so far discovered no remedy that does not damage or 

 destroy the tree. In this class we find the pear- blight, which has 

 wrought such destruction in our State, the olive-knot, and kindred 

 diseases. The disease, in these cases, finds entrance in some tender part 

 of the plant. In the case of the pear-blight, it is through the blossoms 

 largely, and being taken up in the sap spreads through the cambium 

 layer and gradually involves the whole tree. It is insidious in its work, 

 and often passes unnoticed, until the greatest damage is accomplished. 

 The germs in some of these diseases may be carried by the wind, but 

 more frequently insects are the principal vehicles of their spread. In 

 the case of pear-blight, there is little question but that our honey bees 

 are an important source of infestation, flying as they do from blossom 

 to blossom and carrying the germ to the most susceptible point of entry 

 of the plant. At the same time I question very much the advisability 

 of shutting the bees out of the orchards, as other insects and wild bees, 

 which can not be removed, are equally culpable. 



The remedy for this disease is to injure the trees. When the tree is 

 making its most vigorous growth, the sap is flowing freely, and it is 

 then that the germs spread most rapidly. As the season advances, the 

 growth stops, the wood hardens, and the disease is checked. If the trees 

 are neglected, uncared for, and stunted, the disease will be largely 

 checked. The disease may be stopped to some extent if, when the 

 first evidences of it are observed, the diseased portion is cut back 

 Avell below the point of attack. The trees should be gone over in the 

 fall, and all wood showing any indication of the disease removed; this 

 should be followed during the growing season by the removal of all 

 portions which have been attacked; and all wood removed from the 

 trees should be burned, and all tools and implements used for pruning 

 should be disinfected. For this purpose, a solution of 5 per cent carbolic 

 acid is effective. Spraying, fumigating, and all other external remedies 

 are utterly worthless, as the disease is in the sapwood of the tree, pro- 

 tected from all external influences. 



There is yet another group of diseases, which have proved very serious, 

 and which are as yet unclassified. These are such as the peach yellows, 

 peach rosette, Littles, Anaheim disease, etc. It is not yet known what 

 causes these diseases or what remedies can be applied. As they are not 

 responsive to external remedies, however, it is quite probable that they 

 are bacterial in their origin. Fortunately, except for the vine disease, 

 these scourges are unknown to our fruit-growers, and by quarantining 

 against the sections in which they exist, we may be able to prevent 

 them from obtaining a foothold in California. 



For practical purposes, pests of deciduous fruits, like the diseases, may 

 be roughly classified under two heads — insects that gnaw, and insects 

 that suck. Under the former classification, we include the larvae of the 

 10— F-GC 



