The San Francisco call., 1909-11-11
SHOWS CONTROL OF
PEAR TREE BLIGHT

BERKELEY, Nov. 10.-Three years
work of the university college of agri-
culture directed against the trouble
some pear blight has resulted most
favorably, according to the report is
sued from the department today by
Prof, Ralph E. Smith, director of the
southern stations and plant pathologist
of the university. The report covers
the period between July 1, 1906, and June
80. 1909, and is the most comprehensive
issued on particular campaign against
an enemy to a California industry
The work of the university in co-op-
GRAFTON with the United States depart
ment of agriculture has cost more than
$4,000, and has necessitated the con-
tinuous employment OF from to 12
men for two years. Every pear grower
in these sections of the state where the
crop is heavy has been visited and
more than 100000 pear trees examined
several times.
ABLE TO COMBAT DISEASE
Although Professor Smith does not
say that the blight of the year has been
eradicated, he declares that the knowl-
edge gained from the study of the, dis
ease will prevent any great losses
from the blight in the future. Profess
sor Smith continues:
One of the most valuable results obtained from
the work done thus far has been the experience
gained as TO the behavior Of the disease under
California conditions. OF these pecuiiarities
there are two which seem of particular import
ance since they the factors which have
most largely prevented complete control of pear
blight in California: these are: first, the very
large amount of Infection of twigs and green
shoots which occurs with no relation to the bios
SONS; second, the large number of trees which
become infected in the body near the ground
in the butt underground. In the latter case the
blight runs down into the roots and often girdles
and kills trees which, in the tops, appear per-
fectly healthy, or only slightly affected with the
disease SO far as the usual form of the disease
is concerned occurring In the top of the tree
with the Infection mostly through the blossoms,
our growers have learned to handle it with con-
siderable success by the usual methods where
the work is done carefully.
The one most discouraglng and battling feature
OF the disease has been that mentioned, where
large numbers of trees in orchard apparently
fected in the butts and thus beyond redemption
ected In the butts and thus beyond redemption
by the methods Of handling blight in the tops.
Could this difficulty be overcome we believe that
pear growing would again flourish sound
basis, though requiring more care and attention
than at present.
The efforts of the department have
also been directed against the walnut
blight, a cure for which Professor
Smith has found In the improved cul-
tural practice, thus increasing the pro-
duction of the trees. He continues:
The greatest possibilities in this direction
seem to lie in soil fertilization, and extensive
experiments along such lines are being carried on
by this division. Some of these are now in
their third season ana ought 10 show results in
the crop OF 1903. 1t is already very evident that
in spite of the disease the production of most of
the present orchards could be greatly increased
by fertiizlng the soil, IL the most economical
method In this respect determined. In re-
gard 10 irrigation. also. as affecting the condi-
tion of the trees, considerable benefit is being
by the determination of the best
practice In this regard.
The ultimate solution of the blight problem
appears to be in the growing of walnuts Immune
to the blight desirable types of which are
already in existence. Much work is being done
at the Whittier laboratory in this direction.
This involves the growing of grated rather than
Seeding trees and thus opportunity Is given for
choice regarding both the root and the top of
the tree. Each is of great Importance. Exten-
sive paintings have been made at the laboratory
of nuts of various kinds and sources for the pro
duction of root stocks. These represent several
species of walnuts and also hybrids between diff
ferent species. Experience has already shown
that in the native California black walnut we
have a more hardy root than that of the English
walnut, one that is more capable Of fourishing
under unfavorabie conditions and one with a
much wider range OF soil. The native walnut
varies however. in individual trees almost as
much as the cultivated species. so that there
is for careful selection and discrimination
in growing root stock. The California walnur
is also divided less distinctly into two
separate species II may be classed as the south
ern California aud northern California typez-