John C. Walker
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The few cabbage plants that could survive the disease were interesting to these
men. Healthy plants from the most severely infected field were to be selected for
seed production — stored over winter and replanted the following spring. Three
plants were selected from a field of over 25,000, they were carefully stored and
replanted in the same infected field of Matt Broesch. One night Mr. Broesch’s cow
got loose and partially destroyed two of the plants! The cabbage industry was
saved, however, by that single plant that was spared.
John Charles Walker was born on July 6, 1893 in a house on Lathrop Road
that still stands just north of 21st Street. He entered Beebe grade school, attended
Racine High School where he graduated with the highest scholastic record of any
boy in his class. In 1910 he entered the University of Wisconsin. In the spring of
1912 he went to Dr. L. R. Jones and stated that he thought he would like to major
in plant diseases, the new science recently named Plant Pathology. Dr. Jones’ answer
to this was, “That is fine, Charley. You have quite a problem in your own backyard,
a disease in cabbage that we know very little about. You can start working on that
this summer during your vacation” — and for more than 45 years J. C. Walker has
been working with cabbage.
RESEARCH CONTRIBUTIONS TO WISCONSIN
Wisconsin is a giant among states in the production of vegetable crops for fresh
market and processing. It leads all states in production for processing of peas,
sweet corn, beets, and carrots. It is second in production of cabbage for sauerkraut,
and cucumbers for pickles. It is a leader in production of onions (both sets and
bulbs), potatoes, beans, and lima beans.
ACCOMPLISHMENTS
Cabbage
Seed of the first yellows-resistant variety of cabbage, Wisconsin Hollander
No. 8, was being increased locally as rapidly as possible. Slightly less than
100 pounds were produced in 1916, hardly enough to meet the needs of the local
growers. Seed production in 1917 exceeded 800 pounds. (In 1957, forty years
later, total production of yellows resistant cabbage seed in this country exceeded
135,000 pounds!) At this critical time another disease, Blackleg hit Wisconsin.
This was a disease that was transmitted from one crop to another through seed,
unlike cabbage yellows which was soilborne. The success of the new yellows-
resistant program was doomed unless blackleg could be controlled. J. C. Walker
was handed this assignment and in short order he had the disease under control.
He showed that if cabbage seed was produced in the Pacific Northwest instead of
in Wisconsin it was disease-free. This not only saved the day for the cabbage
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Wolf Prize in Agriculture
industry in Wisconsin but was a prime factor in the shift of the cabbage seed
industry from Northern Europe to the United States.
Walker next turned his attention to the yellows disease which had been brought
under control by the development of the Wisconsin Hollander No. 8 variety. This
variety was only partially resistant and was not suitable for all uses. Walker
discovered a more desirable type of resistance and has given to the growers some
12 or 15 different varieties of resistant cabbage.
The Clubroot disease of cabbage is as ancient as the crop and control of it has
defied man through the centuries. Walker turned his plant breeding skill to this
problem and has developed resistance to it. He took resistance from curly kale and
transferred it to cabbage. Control of this most serious disease is now certain.
1914. Same field, the first yellows resistant
strain of cabbage. In the background,
right to left, the student J. C. Walker,
Dr. L. R. Jones and W. J. Honsche.
In recent years kraut manufacturers in Wisconsin have been deeply concerned
about a disease called Tip-burn. This disease occurs in lettuce also and results in
shreds of dead tissue in both crops. Walker is now working on this problem and is
on the track of a way to control it.
Onion
Walker did some of the early work showing the effect of artificial heat on the
drying of onions in storage and the relationship of their preservation to disease
control. This work was done about 40 years ago. With the recent change in onion
production, mechanical harvesting and storage in bulk, with large amounts of air
being forced through these bulk piles of onions, every grower today is referring to
Dr. Walker’s paper and is using heat to cure and control the diseases of onion in
storage. He made the original technical descriptions of two of the neckrot diseases.
Smut is Wisconsin’s worst disease of onions. Our basic knowledge on the effect
of soil temperature on the occurrence of this disease was made by Walker. He took
the idea of dripping formaldehyde solution on the onion seed as they are planted
and worked out a practical application that saved the onion industry in Wisconsin.
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John C. Walker
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Onion smudge is a disease of white but not of yellow or red onions. Walker
showed that the pigments that form the yellow color in onions acted as a chemical
substance forming resistance to smudge in onions. White onions, without this
chemical substance, are susceptible to smudge. This is the most classical piece of
research on the nature of resistance due to chemicals that has ever been worked out.
Walker was instrumental in starting a national program for the development
of onions resistant to pink root, a disease of increasing importance in Wisconsin.
Peas
The story of peas differs little from that of cabbage. Pea wilt was ravaging the
fields of southern Wisconsin. Walker tested some 250
varieties of peas and found
some to be naturally resistant. With Professor E. J. Deiwiche, he developed resistant
varieties suitable to Wisconsin’s needs. Today, Wisconsin’s 150,000 acres of peas
are planted to these resistant varieties.
Beets
As Wisconsin’s beet canning industry developed, it was faced with a serious disease
known as black spot or heart rot. This disease was shown to be due not to a
parasite but to a lack of boron in the soil. Walker showed that the disease could be
controlled by adding boron in minute amounts to the soil or by spraying it on the
leaves.
A few years ago Wisconsin’s great pickle industry was
threatened with extinction
by epidemic occurrences of the scab disease and by severe losses from the mosaic
disease. Walker crossed a scab-resistant slicing variety with a mosaic-resistant
pickle variety and developed varieties of the pickle-type resistant to both diseases.
These varieties are saving Wisconsin’s agriculture over one million dollars each year.
This picture shows the difference between
the death and survival af an annual 2½
million dollar industry which is directly
attributable to the work of Dr. John
Charles Walker.
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