Report on the Agricultural Experiment Stations, 1952 Page: 54
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54 REPORT ON EXPERIMENT STATIONS, 1952
the barberry by the Minnesota station. These comprised 18 races but
15B was isolated most frequently, emphasizing again the need for
eradicating the rust-susceptible barberries as quickly as possible.
Preliminary reports obtained on the development of stem rust in 1952
indicate that race 15B is causing serious reduction in yield of spring
wheat in certain areas.
In greenhouse tests the Kansas station (coop. USDA) found excellent
resistance in wheats to many races of leaf and stem rusts,
including 15B. The principal sources of this combined resistance
were Chinese2 2X Agropyron elongate, Egypt Na. 101 X Cheyenne,
Timstein x Pawnee2, Bobin-Gaza-Bobin X Pawnee, the Brazilian
variety Frontana, the Mexican variety Kentana, several selections
from Kenya Colony, Red Egyptian, and many selections from complex
wheat X Agropyron crosses.
Control of the cereal rusts depends on the constant development of
new varieties that are resistant to the changing races of the parasites.
One of the problems that has hampered the cereal breeder and pathologist
in this work has been the preservation of the parasite. It
can grow only on the living host plant and formerly could be stored
for only short periods in the laboratory. This made it difficult to
maintain collections of the many races of the rust organisms and to
compare results among the investigators cooperating in rust research.
Within the last 2 years, a new method, called lyophilization, has been
successfully applied to rust by the Iowa station (coop. USDA) on
this problem. Collections of Puccinia coronata, the oat crown rust
parasite, have now been in storage up to 22 months with no significant
loss of viability or change in pathogenicity. Similar results also
have been obtained with the oat stem rust fungus, P. graminis avenae,
and it appears that the method is applicable to any of the cereal rusts
and perhaps to other obligate phytopathogenic fungi. The technique
itself is simple and requires only ordinary laboratory apparatus.
Verticillium wilt of cotton
The Arizona station continued investigations on the verticillium
wilt of cotton and found that the causal fungus can pass from the
branches and pedicels into the bolls. The lint in immature bolls was
a reasonably good medium for growth of the fungus, which also grew
in the lumina and walls of the fibers. Experimental work by the
New Mexico station (coop. USDA) indicated that several cultural
practices may help to control this disease. These include a 1-year
rotation with legumes or a small grain planting in high beds, and thick
spacing of plants. A 15- to 20-percent increase in yield of seed cotton
per acre was obtained following the legumes and a 37-percent increase
occurred following barley. There was 30 percent less disease and yield
was 16 percent higher, on the average, in the thick planting than in
thin planting. Extra-high-approximately 15 inches-double-row
beds resulted in decreased wilt percentages and increased yields. This
is due in part to an increase in soil temperature of from 4 to 5 F.
in the high beds over that in the conventional double-row beds.
In the greenhouse it was found that disease was most pronounced
at a constant soil temperature of 78 F. As the soil temperature was
increased, the severity of damage was reduced sharply and at a constant
soil temperature of 90 almost no damage occurred to the cotton
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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/m1/56/: accessed November 14, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.