state: pomological society. 41 



effect produced by ringing or partially ringing the tree. Growth 

 goes on above the ring but stops below for the food supply is 

 entirely cut oft'. 



Not all the manufactured food is used at once for growth but 

 some of it is stored away in the tissues of the stem and root for 

 future use. This is especially true toward fall when the wood 

 is "ripening up," as we say for winter. Then the tree is actively 

 storing up food material, largely in the form of starch to be used 

 the following spring. In the early spring, the food materials 

 begin to go into solution again, pass up through the vessels with 

 the water current and are used in building up the young leaves 

 till thy are ready to go into the food manufacturing business 

 on their own account. 



After a severe winter we are sure of a large number of 

 bundles of apple twigs to examine during \lay and June. The 

 owner in each case is very much alarmed, saying that some 

 unknown contagious disease has appeared in his orchard and 

 is sweeping through it like wildfire. In some cases the trees fail 

 to put forth leaves at all. With these trees the orchardists 

 readily recognize that they have winter killed. ]\Iore often the 

 leaves appear as usual and frequently blossoms are also put 

 forth. In less severe cases the fruit sometimes sets. Suddenly 

 the leaves begin to wither and fall off and the bark on many o£ 

 the younger limbs and twigs withers and dries out. Bearing in 

 mind what has just been said with reference to the structure of 

 the tree and the storage and movements of food materials the 

 explanation of the cause is now easy. 



When the ground begins to warm up in the spring the sap 

 current from the roots starts up through the vessels of the wood 

 through the trunk, limbs and twigs to the buds. The dormant 

 buds on the trees are quite well protected from frost and appar- 

 ently can withstand greater variations in temperature than the 

 smaller limbs. The stored food materials go into solution and 

 are carried along with the water current, the buds swell and 

 begin to put forth leaves as usual. If the frost injury is not 

 severe the trees will have a sickly appearance for a season or two 

 and may gradually recover unless another cold winter follows 

 to finish them. More frequently the leaves fall as has already 

 been described. Here we have stored food materials sufficient 

 to start the young leaves, but this soon gives out. So many of 



