MAINE) AGRICULTURAI, EXPEIRIMENT STATION. 191O. 395 



as recommended for apple scab and other fungous diseases, 

 would doubtless do much to hold the lichens in check, if not de- 

 stroy them altogether. Hence, if the orchard is well cared for 

 and sprayed it will not be infested with lichens. 



Parasitic Diseases, 

 diseases oe the eouage and fruit. 



Scab. Probably no other disease of the apple is of so much 

 economic importance to Maine orcharding as the common apple 

 scab caused by the fungus Ventiiria pomi (Fr.) Wint. The 

 losses from this disease are not so much in the destruction of the 

 fruit as in the lowering of its market value. On account of the 

 attacks of this one disease, which is largely preventable, the 

 financial returns from the orchards of many sections of the 

 country are reduced from 25 to 50 per cent yearly.* Were it 

 properly controlled in Maine a large proportion of the crop of 

 some varieties which now goes as No. 2 and No. 3, might be 

 marketed with the No. i grade. Moreover where spraying op- 

 erations have not been generally practiced the importance of 

 this fungus is in no way realized. For years it has been com- 

 mon and widespread, particularly on certain varieties and the 

 orchardist has learned to regard it as one of the things to be 

 expected and not as something which can and should be pre- 

 vented. 



The apple scab fungus may attack the flowers, twigs, leaf- 

 stalks, leaves and fruit but it is upon the last two that its appear- 

 ance is most prominent. While severe attacks on the leaves do 

 much to weaken the trees, often causing considerable defolia- 

 tion, the direct monetary loss to the orchardist is greatest from 

 the effects of fruit injury for the reasons mentioned above. 



Scab appears on the leaves in the form of a superficial, some- 

 what velvety, olive-colored growth, darker than the leaf green.j 

 This growth is more likely to be observed on the under side of 

 the leaf but both sides may be attacked. It may occur in spots 

 but is frequently more abundant along the line of the mid-rib 

 and large veins. The later stages may be compact, thin-scurfy, 



*Duggar, B. M. Fungous Diseases of Plants, p. 265, 190Q. 

 t Before the spores begin to form the affected areas are of a Hghter 

 green than the healthy parts of the leaf. 



