some of the strands of wool but this activity in and about the
trees means a decrease in injuries from insects--a worthwhile exchange.
When an unusually large swelling at the graft union appears, it is
certain that the plant needs protection such as I have described. Such
swellings result from a too-rapid multiplication of cells, a condition
which leaves the union weak and susceptible to injury. Although a union
is never entirely safe, even after many seasons of growth, each year
adds to the safety factor by the development of rough, cork-like bark. I
suggest the use of a woolen guard for several winters, by which time
this outer bark should be able to do its protective work alone.
A successful but rather expensive method of winter protection, both to
the graft itself and its union with its host, is to enclose the entire
tree with a box-like structure consisting of four corrugated aluminum
roofing sheets set up on their ends and countersunk into the ground
about six inches. The purpose of countersinking these below the ground
surface is two-fold: it stiffens and braces the structure and prevents
the intrusion of mice and other rodents, which may also appreciate both
the shelter and possible food supply contained therein. By fastening
these sheets together with a stout wire you can depend on the structure
to stand up against wind and snow pressures. Fill the entire inside with
forest leaves, oak leaves preferred, as their insulating quality is the
best and they are slow to rot and ferment.
When working with semi-hardy plants in a cold climate, avoid fertilizing
and cultivating the ground after the first of August. Doing so
stimulates late growth and such growth is very likely to be badly
injured during the winter months. If fertilizer is used, it should be
early in the spring, as soon as the ground is free from frost. Trees
which persist in growing late into the fall are more subject to winter
injury. Protective measures to avoid their doing so by inducing an
earlier dormancy, include keeping the soil around them dry and exposing,
somewhat, the roots near the trunk of each tree.
My last word of advice in raising what might be termed semi-hardy trees,
is to grow them in sod, the ordinary quack grass, June grass, bluegrass
or other natural grass sods which can be found on your planting site.
Although this will probably hold back your tree development for a few
years, until the roots are thoroughly established in the
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