MISCELLANEOUS. 



SOME COMMON FUNGUS DISEASES AND THEIR TREAT- 

 MENT. 



(By Bayard P. Floyd, Assistant in Botany, University of Missouri.) 



APPLE SCAB. 



Venturia pomi {Fr.) Went. 



The apple scab is the most injurious of all apple diseases. It at- 

 tacks the foliage and fruit, causing injury and destruction to both. 

 There are two important stages of this disease. First, the summer 

 stage, in which the disease attacks the buds, leaves and fruit; second, 

 the winter stage, in which spores are formed on the fallen leaves, or 

 possibly on twigs. These spores cause a new infection in the spring. 



The vegetative part of the fungus lives in the tissue of the plant, 

 spreading through the leaves and fruit as it is formed. The scabs are 

 produced by the fruiting fungus, which breaks down the tissue and 

 sends up erect hyphae, from the tips of which are cut off small spores. 

 These, carried by the wind or insects, cause a new infection. In the 

 spring, soon after the leaves unfold, round, light greyish to olive spots 

 or scabs appear. These may coalesce, forming large areas of such 

 abundance that the leaf will shrivel and fall off. Earlier in the season 

 the buds and blossoms may be attacked. 



The fruit is the part that is most seriously attacked ; on it the dark 

 brown of blackish scabs develop from small circular spots to large irreg- 

 ular patches, which may cause the apple to be one-sided and to crack 

 open. After cracking open, the soft rots will attack the fruit. The 

 stems may also be attacked, allowing the fruit to fall. The twigs are 

 rarely attacked. 



This production of scabs is the summer stage. The vegetative 

 part of the fungus in the leaves, which have fallen to the ground, will 

 live there during the winter. In the early spring it will develop minute 

 black bodies in the tissue of the dead leaf. These, on opening, will 

 liberate spores which will infect the new leaves. This constitutes the 



