Report on the Agricultural Experiment Stations, 1952 Page: 53
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REDUCING LOSSES FROM PLANT DISEASES 53
Nematodes Damage Many Crops
During the past few years the stations have recognized that nematodes
or eelworms are causing injury to some of our more important
food plants to a greater extent than was thought possible a few years
ago. Today approximately 20 stations conduct research on various
phases of the nematode problem.
Nematodes have often been blamed for plant injury when no other
cause was evident or when they were associated with plant tissues in
large numbers. Since the propagation of nematodes in sufficient
quantity for research purposes is sometimes difficult, proof of their
pathogenicity has often been neglected. By varying the number of
nematodes (Paratylenchus hamatus) associated with celery roots, the
Connecticut Agricultural Experiment Station found that the amount
of injury and stunting of the celery plants was in direct proportion
to the number of nematodes present. Previously this same nematode
had been reported only on figs in California. Tests with methyl
bromide-treated soil showed that plants growing in such soil
weighed four times as much as those growing in nontreated
soil. The Oklahoma station found in trials with muskmelons
that row applications of soil fumigants for nematode control
gave yield increases of 25 percent, which was practically equal to those
obtained by treating entire soil areas. Only one-third as much ethylene
dibromide was needed when applied in the row as when applied by
A survey of peanut fields by the North Carolina station showed that
70 percent were infested with the peanut root knot nematode in spite
of the fact that a 2-year rotation was used on many of the farms.
There was very little difference between the action of common nematicide
materials applied in the row in reducing nematode damage.
On tobacco, a cyst-forming nematode was found by the Connecticut
Agricultural Experiment Station that was morphologically indistinguishable
from the golden nematode that attacks the potato. The
tobacco cyst nematode can also attack tomato plants, though more
weakly. It does not attack potatoes, however, nor does the golden
nematode attack tobacco.
Determinations made by the Minnesota station showed that the
virulent race 15B of stem rust which caused losses of over 10 million
bushels of durum wheat in North Dakota and Minnesota during 1950
was found to be widespread in 1951. Partly because of drought in
much of the area where the summer spores often overwinter and partly
because of below-average temperature in the spring wheat area, stem
rust did not develop rapidly in 1951, and consequently, it did relatively
little damage. In 1951, race 15B, however, was found from Texas and
Mississippi northward to Wisconsin, Minnesota, and North Dakota,
and from Virginia and Pennsylvania westward to Colorado, Wyoming,
and Montana. Of the 27 stem rust races identified by the Minnesota
station from 686 collections, comprising 950 isolates, race 15B made
up 21 percent of the total. It was exceeded in prevalence by only one
other race, namely 56. Also, 41 isolates of stem rust were made from
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United States. Office of Experiment Stations. Report on the Agricultural Experiment Stations, 1952, book, January 1953; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc5990/m1/55/: accessed May 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.