BITTER PIT AND SIMILAR FRUIT SPOTS^ 



George E. Mattus, Horticulture Dept. 

 VPI and State University, Blacksburg, Va 



Bitter pit has long been a disorder in the apple growing 

 areas of the world but pitting seems to be more of a problem today 

 in the U.S. on varieties that once had less bitter pit. 



Cork spot, a problem in Yorks for many years, has in recent 

 years become a problem in Red Delicious and occasionally on other 

 varieties in the Cumberland-Shenandoah apple growing area. 



Bitter Pit 



Bitter pit is evident as small, brown, soft, dried pits of 

 collapsed tissue. Most of the pitting is just beneath the apple 

 skin and primarily in the blossom half of the apple. 



Although some bitter pit develops in the orchard before pick- 

 ing (tree pit), in the Virginia area most of the pit develops af- 

 ter harvest (storage pit). 



One current view is that low calcium 

 pies results in bitter pit although there 

 relationships. 



in the peel area of ap- 

 are many complex inter- 



The question arises as to the causes of the increased inci- 

 dence of bitter pit in recent years. 



We are no longer coating leaves with calcium as we did with 

 lime used in many spray combinations years ago. Today's red sports 

 can be grown at higher nitrogen and higher vigor levels and still 

 develop good red color. With higher nitrogen and more vigor, there 

 tends to be lower calcium in the fruit and increased bitter pit. 

 Also, present day orchards have more young bearing trees which de- 

 velop more pit than older trees. Bigger and better leaf surface 

 than in the "old days" provides more fruit shading and more leaf 

 competition for available calcium in the tree. Earlier red color 

 of apples with improved red sports and use of scald inhibitors now 

 permits earlier picking for storage which results in an increased 

 amount of bitter pit. 



A listing of factors that may influence the incidence of bit- 

 ter pit should help in considering the inter-relationships that 

 may relate to this disorder. The simplified general trends of 

 factors are indicated below according to the world-wide results up 

 to 1971 in the view of this author. 



1 



Excerpts from an article that appeared in Vol. 52 of Horti cul tural 

 News published by the N.J. State Horticultural Society, Sept., 1971 



