e by diseases, and thus
the success or failure of nut tree plantings, is the ignoring of soil
and fertilizer requirements. Trees weakened by drought, because they are
on a site having a soil too shallow for good root growth, are much more
subject to attack even by weakly parasitic fungi than those growing on a
site with deeper soil. Innumerable dying twigs and branches with fungi
growing on them are sent to the U. S. Department of Agriculture or State
experiment stations with requests that the disease be identified, when
the real trouble is lack of water for the roots. Weak trees are much
more subject to winter injury than vigorous ones.

Trees require a good supply of plant food materials and water to produce
profitable crops. Tho heaviest bearing chestnut trees we have observed
were grown in an irrigated orchard in California and in a poultry yard
in the East where chicken droppings actually formed a mulch under the
trees. However, if you wish to kill a young chestnut tree quickly, just
apply a very heavy application of chicken manure; the point is that
trees must become adjusted to chicken manure by gradual applications.

Another way to damage a tree is to keep it growing late in the fall by
cultivation and fertilizers so that it does not harden off properly.
Many plantings, representing heavy investments, fail because of lack of
organic matter in the soil. This is related to water-holding and
water-supplying capacity of the soil, and lack of proper fertilizer. Dr.
Harley L. Crane and his assistants, in their work with tung and pecan
trees, have shown the vital need for certain elements on some soils.
Trees weakened by the lack of these elements are early prey for some
diseases. The element most frequently deficient is nitrogen, but
sometimes boron, copper, or iron is lacking; or the elements are not in
balance, because of the excess of some, or the lack of others.

By adjusting the various soil, water, and site factors necessary for a
continuous, vigorous growth of trees, many so-called disease conditions
are eliminated. Many fungi and viruses, however, will attack trees in
the pink of condition; a few of the more important of these are treated
in the following sections.

+Chestnut Blight+

The destruction by blight of the native stands of the American chestnut,
and of the small eastern orchard industry based on European and American
chestnuts and their hybrids is almost complete. Blight has been found in
the