hould be practiced at that time, which
would tend under suitable conditions to stimulate late growth of the
trees. This is because some trees like the Persian walnut are slow to go
into rest at best and practices that stimulate late growth of the trees
cause them to be susceptible to cold injury especially in late fall or
early winter. I have seen very severe injury and killing of pecan trees
in south Georgia as a result of spring fertilizer applications which,
because of drouth, did not become available to the trees until late
August and early September and then caused second growth of the trees.

In the case of walnuts and pecans, especially, but also others than are
not sprayed for the control of diseases and insects, it is not uncommon
for the trees to become defoliated in late summer and while bearing a
crop of nuts. Very often this premature defoliation results in the
production of a new crop of leaves and some shoot growth. This is one of
the worst conditions one can have in an orchard, for the nuts are
certain to be very poorly filled and the trees especially susceptible to
cold injury.

In such a case as this, the nuts withdraw carbohydrates, proteins and
minerals from the leaves and wood of the tree for their development and
the production of new leaves and shoots has a like effect. This all
results in such a severe removal or using up of the materials involved
in the development? of hardiness that such trees are very susceptible to
cold injury.

Woody plants to be resistant to cold injury must be well nourished.
Unbalanced mineral nutrition of trees is a very important factor in
determining the amount of injury they may sustain from cold weather. In
the various parts of the United States the soils on which fruit and nut
trees are grown generally do not supply in adequate amounts some one or
more of the essential elements required in their nutrition. This
condition results in unbalanced nutrition, in that too much of certain
elements is absorbed by the trees and too little of certain other
elements. Under severe conditions this causes the leaves to be abnormal
in size or in form, for them to be chlorotic or to scorch or burn, or
for them to drop prematurely. Such leaves do not function properly, they
are not able to carry on photosynthesis at a normal rate and hence do
not make sufficient plant foods of the proper kinds to properly nourish
the trees. This results in disorders of various kinds said to be due