130 HOUTICULTURAL MANUAL. 



and as stated by Professor Card fruit will color and develop 

 in the interior of thick-topped trees, and it often happens 

 that orchard fruits of all kinds exposed to the sun are 

 scalded on the exposed side by sun heat. Young trees 

 properly shaped when started in orchard are mainly grown 

 on the let-alone principle, except in the way of cutting out 

 dead twigs and such weak interior growth as cannot have 

 exposure of leaves to the air and sun. The thick-top 

 principle of fruit-growing is sustained by the fact that 

 where the new growth of young orchard trees is cut back 

 in autumn for three or four years in succession the top 

 becomes very thick on the outside. Yet these trees bear 

 finety colored fruit beneath the thick exterior and better 

 average crops than thinner-topped trees of the same 

 varieties. But in quite moist regions of the East and 

 South where moss grows on north-exposed house-roofs, or 

 Spanish moss hangs down from tree branches, the old plan 

 of thinning out to let in the sun will always be practised. 

 144. Heading Back Old Apple- and Pear-trees. With 

 the thick-topped plan of the prairie States and the arid 

 regions, or the more open-topped plan of the moister 

 belts, the bearing wood as the trees get old becomes far 

 removed from the center of the tree. The time has now 

 come for severe cutting back of the top, as is practised 

 with old peach-trees. With the apple and pear in the 

 dent-corn belt this severe heading back is an epoch in the 

 life of the tree, and the shock is too severe if the cutting 

 is all done at one time. The safest plan is to cut one half 

 tbe tree at a time, deferring the work on the other half to 

 the next year, when the growth of new shoots is a relief 

 from the injury liable to occur from sap-pressure. If two 

 years are taken for the severe heading back of old orchard 

 trees in connection with culture and manuring, new 

 growth starts vigorously from the cut-back stubs and the 



