FRUIT NOTiilG - August, 1939 



v;. H. Thies 

 Extonsijn Horticulturist 



The Internal Cork Situation 



A mid-suniffler drought has again resulted in some browning around the 

 cor« of certain varieties of apples where grovm on less favoruble soils. This 

 condition has been observed in at least 20 v^fidely scattered Massachusetts or- 

 cn.urds and has also been reported in Rhode Island and Connecticut. The injury 

 ranges from a tinge of brown to irregul^vr corky areas extending from coro to 

 skin. Only in the more seriously affected fruit can the dt.raagt^ bu dctoctud 

 without cutting tne apple. Appl'js v;ith much intern;;l cork generally h..vo a 

 roughened or pebbly surface. 



The relation of internal cork to the subsoil on which the tree grows 

 is Vi/ell established. V/h^re the tree is sliallovi; rooted because of an impervious 

 hardpan, ledge, or high water table at certain seasons the fruit is subject to 

 tne development of internal cork. Also, where the tree is underlain by coarse 

 sand or gravel incapable of retaining enough moisture for an extended dry spell, 

 internal cork is likely to appear. Varieties most commonly damaged are Mcintosh 

 and Cortland, although some rather "corky" Baldwins have been observed this 

 Season. 



A Careful survey of the extent of intorn-1 cork in a number of Massa- 

 chusetts orchards shov;s much variation even in adjacent trees. V/e sometimes 

 find a tree vidth normal fruit vi/ithin 20 feet of a tree bearing "corky" fruit. 

 And in som.e cases cert^-in linos sliow much more internal cork than the rest of 

 the tree. One grov^er reports finding internal cork only in tiiose trees along 

 a hard packed driveway where rain water fails to penetrate. This suggests a 

 moisture relationship. Little relation to hurric-ne damage has been noted. 

 One would think tn„t a tree with injured roots -would necessarily suffer in a 

 dry season. But the soil type seems to bo a more important ft^ctor. A coi.ipu.r- 

 atively few roots are app..rently capable of supplying the top with water pro- 

 vided the soil is deep, well drained and retentive. 



This brings us to the question "VvTict can we do about it?" Unf ortun-.tely , 

 there is little we can do to improve the present season's crop. But we ought 

 to eX-mine apples in all parts of the orchard to locate the affocted trees in 

 order th-^t fruit showing internal cork may be kept sep^.rate from normal fruit. 

 Then the "corky" fruit should by all means be kept off the generd market. 

 Our Mcintosh reputation is in danger if we sell fruit of that v..riety showing 

 internal cork for anything but what it is - a very inferior apple. One needs 

 only to eat a "corky" apple to appreciate how inferior at is -.nd how necessary 

 thct we inform the buyer of the actual situation. Vi/e often talk about keeping 

 inferior fruit off the market. Here is an excellent place to start, in cor.- 

 pa.ny with Mcintosh growers in other l\lev; England states. 



Next spring .,11 susceptible orchards should be given a light applica- 

 tien ef boi-ay, applied either en the soil or l.s a spr-y on the f ullage. The 

 amounts will be announced vi^hen the proper seasen arrives. Striking results 

 have been obtained freiii such treatments made in previeus yeare. In ne orchard 



Isi-ued by the j^xt-ns^en Service, Willard A. Munson, director, in furtheranc 

 uf Acts of May 8 and June 30, 1914-, Hasaachusetts State College, United States 

 Department of Agriculture, ..nd County iitensien Services c^ eper-iting. 



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