144 TWENTY-EIGHTH FRUIT-GROWERS' CONVENTION. 



all parts of the globe, and with them have also been imported pests and 

 diseases that were hitherto unknown to us. There is no such thing, it 

 is said, as unalloyed good, and so in this case, in our efforts to improve 

 our stock, we have become the agents for the introduction of unnum- 

 bered ills and many pests, which were originally confined to a limited 

 area, but which have now become almost world-wide. 



Now, the matter that bothers us is, how to preserve what is good 

 and eradicate that which is ill; and it is to this end that some of the 

 ablest minds of the age have devoted their lives, and we have numerous 

 methods, preventive and curative, adapted to the various diseases or 

 pests to be reached. 



Tree diseases may be roughly classed under two heads: fungous and 

 bacterial. Among the former, Ave have peach curl-leaf, shot-hole fan- 

 gus of the apricot, apple scab, rose rust, mildew, and many other forms 

 with which we are all too well, acquainted. The cause of curl-leaf is a 

 parasitic fungus, Exoacus deformans. This disease appears early in the 

 spring, at the time when the trees are making their most vigorous 

 growth and the tender leaves offer it the most favorable conditions for 

 growth. It has its origin from two sources: the perennial Mycelium, 

 which remains dormant from a previous season, and from the dormant- 

 spores shed the preceding year, which have found lodgment on the 

 twigs and branches of the tree, awaiting the favorable conditions for 

 growth which the spring affords, when they spring into active life, attack 

 the new leaves and tender growth, and spread with wonderful rapidity, 

 very soon involving the whole tree. Moist conditions are favorable to 

 the growth of this fungus; hence, we usually find it worse in wet 

 seasons, or in sections where there is much moisture in the air, while it 

 is less virulent in its attacks in the drier localities and dies out as the 

 summer advances. 



The history of the peach-tree curl-leaf is in a general way the history 

 of most of the fungous diseases which attack our fruit, and their treat- 

 ment is largely the same. For a winter wash, the salt, sulphur, and 

 lime is the most approved of our known remedies. This is excellent, 

 both as a fungicide and as an insecticide, and should be thoroughly 

 applied as late in the season as it is safe to use it. When the young 

 leaf or fruit buds begin to swell, it is too late to apply it. After the 

 trees are in leaf, the Bordeaux mixture of reduced strength, two pounds 

 of sulphate of copper, two pounds of lime, and fifty gallons of water, 

 may be safely used and is recommended. 



The second group of diseases are those of bacterial origin, and here 

 we have a class that is more than usually difficult to reach. I believe 

 it is even yet a mooted question whether these bacteria can be classified 

 as of animal or vegetable origin, but it is certain that their work is 

 carried on beneath the surface and spreads through the sap of the tree, 



