The nest, which
enclosed over half of the graft union, was partly composed of woolen
fibers which its builder had gathered from barbed-wire fences that sheep
had brushed against. On the exposed portion of the graft union,
discoloration indicated injury and dead cells, but on that part covered
by the nest, all the cells were alive and green. I have improved on the
bird's nest by wrapping a large wad of wool loosely around each graft
union. The value of wool is that it will not collect moisture and so
start fermentation. It allows the cells to breathe, yet protects the
union from the shock of temperature extremes. Birds will inevitably
steal 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.
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