MAINE AGRICULTURAL EXPERIMENT STATION. I3 



Crotch Injury. A peculiar form of injury on apple trees was 

 observed in the summer of 1907. This was later shown to be 

 an undescribed form of winter injury, although in one State a 

 similar appearing trouble has been attributed to the pear blight 

 organism. 



Russetiug of Fruit. Studies made at this Station continuing 

 for a number of years show that russeting of fruit is due to a 

 variety of causes. None of the various forms of spray used 

 which would control apple scab were entirely free from pro- 

 ducing some russeting or spray injury to the fruit, in the case 

 of ver}^ tender varieties like the Ben Davis. Some of the pro- 

 prietary forms of sprays used in experimental work produced 

 severe injury of this nature. Apparently excessive quantities 

 of arsenate of lead will also produce russeting. On the more 

 tender varieties lime-sulphur was found to be superior to bor- 

 deaux mixture on account of the greater amount of russeting 

 produced by the latter. 



Evidence accumulated during several years leads to the con- 

 clusion that in some years there is a considerable amount of 

 russeting of fruit due to the natural causes. The actual factors 

 concerned in this have not been determined, but it is possible 

 that it may be associated with cold, wet weather or late frosts 

 when the apples are small. This russeting sometimes has 

 appeared in the form of bands around the center of the fruit 

 and here there is no doubt about the injury being traced directly 

 to frosts when the apples are small. 



ORCHARD DISEASE STUDIES. 



Beginning in 1908 this Station has been carrying out an 

 extensive orchard disease surve}- of Maine. Before this very 

 little was known of the character and distribution of the various 

 apple diseases in this part of the country, and since that time 

 some very important data have been obtained, both from a 

 scientific and from a practical point of view. Several matters 

 upon which very little or no information was available have 

 been made the subject of rather extended investigations. 



Among the non-parasitic diseases it has been demonstrated 

 that with certain sprays injury may be produced which cannot 

 be told by its appearance from the leaf-spot caused by the black- 



