378 MAINE AGRICULTURAL EXPERIMENT STATION. I9IO. 



moisture. It also assists materially in the control of the fungous 

 and insect pests of the orchard, particularly the latter. 



As has already been pointed out (p. 340), the vegetative por- 

 tions of the fungi causing disease are deep within the tissues 

 of the plant beyond the reach of destruction. Hence sprays are 

 of value largely to prevent the entrance of parasites into the 

 healthy tissues and not as agents to kill them after they have 

 once gained entrance. To be successful the spray must be on 

 the fruit or foliage in advance of the spore of the fungus. 



For many years bordeaux mixture has been practically the 

 only spray used on orchard trees for the control of fungous 

 diseases. While it has proven in every way efficient in con- 

 trolling most of the destructive fungous diseases of the orchard, 

 it has been found that the fruit and foliage of certain varieties 

 of apples are frequently injured by the spray. As a rule the 

 beneficial effects resulting from disease control have far out- 

 numbered the ill effects of spray injury. That certain varieties 

 of apples are susceptible to spray injury, or bordeaux injury 

 as it is frequently called, especially if rainy, damp or cloudy 

 weather is experienced at or immediately following the applica- 

 tion of the spray, has been held responsible in a considerable 

 measure for the lack of more general adoption of spraying by 

 Maine orchardists. In too many cases, the fact that many varie- 

 ties (see list on p. 346) are seldom, if ever injured by bordeaux 

 mixture bas been entirely overlooked. Neither has it been 

 understood that the danger from bordeaux mixture can be min- 

 imized largely, in many seasons, by applying the spray only dur- 

 ing periods of bright, sunny weather, and avoiding its use, if 

 possible, when there are several, successive, cloudy, rainy days. 



However, there has been and is a demand for a fungicidal 

 spray which will control the various plant diseases and still cause 

 no injury to the foliage and fruit of the more tender varieties. 

 Experiments begun by Scott* in spraying apples and peaches, 

 the latter being very susceptible to bordeaux injury, and later 

 taken up by others in various parts of the country, indicate that 

 in the different lime-sulphur sprays we have the promise of 

 something which may control certain of our orchard diseases 

 nearly if not quite as well as bordeaux mixture and if not used 



■*^ Scott, W. M. Self-boiled Lime-su!phur as a Promising Fungicide. 

 Bureau PI. Ind., U. S. D. A., Cir. i, pp. 1-18. 1908. 



