April, 1912.] SOME APPLE DISEASES — TREATMENT. 



The majority of the scab infections are made early in the 

 season, but there is often a second spread of the disease in 

 August. The young scab spots on the fruit at gathering time 

 are evidence of this late attack. They do not, however, show 

 the total amount of damage done by a late spread of the disease, 

 as young scab colonies may continue to develop in storage and 

 unsprayed apples apparently free from scab may develop the 

 disease in storage if taken from an orchard in which a late spread 

 of scab occurred. These scab spots that develop in storage 

 must have their origin either from colonies that were too small 

 to be noticed at the time of picking or from spores carried into 

 the barrel with 

 the fruit. 



The scab 

 fungus, like 

 most ot h e r 

 plants, is 

 greatly checked 

 in its growth by 

 1 o w tempera- 

 tures. Itsgreat- 

 e 5 t develop- 

 ment on stored 

 fruit can there- 

 f o r e be ex- 

 pected in bar- 

 rels from cellar 

 storage or 



which are delayed in reaching the cold storage plant. In some 

 seasons there has been heavy loss from the development of scab 

 on cold storage apples. Storage experiments have shown sprayed 

 apples to be largely or entirely free from this trouble. 



One familiar with the disease as it occurs in the orchard is 

 inclined at first sight to call the storage trouble a separate and 

 distinct disease (Fig. 3). The fungus makes an unusual devel- 

 opment beneath the cuticle before breaking thru and the myce- 

 lium is very dark in color. Consequently black, sunken spots 

 develop on the apple and sometimes attain a diameter of one 

 quarter of an inch before any break is evident in the skin (Fig. 



Fig. 3. — Scab on cold storage apple. 



