scab is the most typical fungus parasite of
the pecan. It attacks the leaves, fruit, etc. It attacks the vessels or
veins of the leaves and frequently enters by means of aphis punctures
which break the skin so that there is no doubt but that this particular
disease is favored by an aphis. We have investigated this disease quite
carefully and carried on a series of spraying experiments for some three
years and there is no doubt about our ability to control it. It can be
prevented by spraying with Bordeaux mixture. You never can tell how many
sprayings will be required. It may take three to ten sprayings to
protect the nuts. The leaves are grown mostly within a month--the leaves
are pushed out within thirty days and you can spray those leaves and
protect them. The weak point in the treatment is that the nut of the
pecan grows steadily from the time it starts to way into September. This
makes a hard problem in spraying as the nut keeps expanding and forming
a new and unprotected surface for an unreasonably long season and they
are susceptible to scab attacks all the time, so you have the problem of
spraying the nuts all summer. The spray does not stick very well on the
nuts. The result is that we advise dodging that parasite by planting the
non-susceptible kinds; it is much better and cheaper. It is certainly an
encouraging thing that you can plant good varieties, that do not scab
badly, and which at the very most require but two or three sprayings to
protect them entirely, and in a great majority of cases, no spraying at
all. Those already are the great nuts in cultivation, like the Stuart,
the Schley and the Frotscher. Most of those good varieties will be
occasionally attacked by scab because of a wet season, just as a variety
of apple which is very resistant to apple scab is occasionally attacked
by that disease.

The pecan has quite a number of leaf-spot fungi and most of those we
have tested by spraying. These experiments have been made in the
nursery where it is more convenient to spray and where the necessity is,
perhaps, a little more pronounced, and there it is, undoubtedly, a
proper practice to spray and fight out the pecan leaf diseases. Bordeaux
mixture is the thing to be used on all occasions. The pecan resists
copper poisoning almost as well as the grape and can be sprayed with
safety.

If a pecan tree has crown gall don't plant it. All nursery trees should
be rejected in planting if they show signs of this