spraying Methods in the Peach Orchard 



Prof. L. Caesar, O.A. C:, Guelph, Out. 



THE chief objects of spraying are 

 to keep trees healthy and vigor- 

 ous, to prevent the fruit from fall- 

 ing to to preserve it from injury by 

 either insects or diseases. The chief 

 insects that weaken peach trees or at- 

 tack the fruit in Ontario are : San Jose 

 Scale, plum curculio, peach borers, and 

 shothole borers, or pin borers as they 

 are often called. Several other insects 

 such as aphids, red spiders, tarnished 

 plant bugs, and peach twig borers are 

 present, but seldom require much atten- 

 tion. 



The chief peach diseases are : Leaf 

 curl, brown rot, scab or black spot of 

 the fruit, powdery mildew, crown gall, 

 gummosis yellows, and little peach. Of 

 these insects and diseases the following 

 can be controlled by spraying: San Jose 

 Scale, plum curculio, leaf curl, brown 

 rot, scab or black spot of fruit and pow- 

 dery mildew. It is true that sprays will 

 control aphids, red spiders, and twig 

 borers, but, as mentioned above, these 

 are seldom of much importance, and so 

 would not in themselves justify treat- 

 ment. 



San Jose Scale and leaf curl can both 

 be satisfactorily controlled by a single 

 very thorough spraying of the trunk and 

 branches with strong lime-sulphur, 

 either commercial or home-made con- 

 centrated. If the commercial is used, 

 it should be diluted about one gallon to 

 eight, but the safest way to dilute either 

 this or the home-made concentrated is 

 to use the hydrometer as described on 

 pages twelve and thirteen in bulletin 

 198 of the Ontario Department of Agri- 

 culture, and make the strength 1.032 

 specific gravity or even stronger. The 

 spraying should be done before the buds 

 begin to swell in spring because the leaf ' 

 curl disease begins to develop with the 

 buds and often cannot be warded off if 

 the spraying is delayed until the buds 

 are almost ready to burst. Damp, cold 

 springs when the buds are swelling and 

 the leaves coming out greatly favor this 

 disease. No one should expect to con- 

 trol it or San Jose Scale unless he will 

 take the trouble to cover every twig and 

 bud and in fact the whole tree with the 

 sprays. In most orchards these two 

 pests are by far the most destructive 

 ones controllable by spraying, therefore 

 this application is much the most im- 

 portant ; in fact, it is the only applica- 

 tion the majority of our peach orchards 

 receive . 



An application of four pounds of 

 arsenate of lead to forty gallons of 

 water to which one or two pounds of 

 freshly slaked lime has been added is of 

 great value against the plum curculio if 

 applied shortly after the fruit has set 



and before it is half an inch in diameter. 

 It is also indirectly valuable against 

 brown rot, because wherever the cur- 

 culios feed on the fruit they give an 

 opportunity to the spores of this dis- 

 ease to enter, hence the prevention of 

 such insect injuries means to a large 

 extent the prevention of brown rot. 



Whenever scab, or black spot as it is 

 often called, attacks and disfigures the 

 fruit, this can be prevented by a thor- 

 ough application of the self-boiled lime- 

 sulphur about four weeks after the blos- 

 soms have fallen. The self-boiled lime- 

 sulphur is a weak spray mixture, and is 

 the only really safe one we yet know of 

 for peach trees after the foliage is out. 

 The commercial and home-made con- 

 centrated will burn unless diluted so 

 greatly that they are ineffective against 

 diseases. The self-boiled is made by 

 putting the lime and sulphur together 

 in a vessel, adding water and allowing 

 the heat generated by the slaking lime 

 to do the boiling. As the details of the 

 method of preparation are given fully in 

 bulletin 198, Department of Agriculture, 

 Toronto, on pages fifteen and sixteen, 

 readers are urged to consult that bulle- 

 tin, which may be obtained free of cost. 



Whenever a grower is troubled with 

 brown rot, the use of the self-boiled 



lime-sulphur about four weeks before 

 the fruit ripens will be found very valu- 

 able. Of course, as previously mention- 

 ed, he must have previously sprayed for 

 plum curculio with the arsenate of lead 

 if this insect is present. The self-boiled 

 lime-sulphur clings to the pubescence of 

 the fruit, so has to be applied nearly a 

 month before ripening or otherwise it 

 will remain on the fruit and render it 

 unsaleable. This is the reason it is not 

 applfed nearer the time of ripening. 

 Usually it is the white-fleshed and early 

 peaches that are most subject to rot and 

 that would be most benefited by spray- 

 ing. 



THE MIIxDEW 



It is very seldom that growers spray 

 for mildew on the leaves, but if a con- 

 siderable number of trees are affected 

 the self-boiled lime-sulphur can be used 

 against this disease also. The mildew 

 is a surface feeding disease and can be 

 killed after it appears, whereas spraying 

 for other diseases is intended to prevent 

 germination of the spores and thus keep 

 the disease from getting a start. 



The different sprayings that peach or- 

 chards may receive and the object of 

 each have now been outlined. Each 

 grower will have to be his own judge 

 as to how many of these applications it 



