In the preparation of the oat cultures the oats, in Erlenmeyer flasks, were 

 soaked for several hours and then autoclaved 1 hour. After cooling, the oats in the 

 flasks were inoculated with the disease organisms and the cultures incubated 10 to 14 

 days . During this period the flasks were shaken daily to prevent the oats from clumping. 



Four infested oat grains were dropped into 7 ml. of preheated distilled water 

 in each of several test tubes, placed in the water bath, and removed after specified 

 periods of time, as described for treatment of subcultures on potato dextrose agar. 

 After the heat treatments the four oat grains in each tube were embedded in agar 

 and incubated. The dishes were examined for fungus growth after 4 to 6 days. 



When Fusarium cultures grown on potato dextrose agar were kept in the water 

 bath for 30 nninutes, the temperature necessary to completely destroy the organisms 

 varied from 131 degrees F. for isolate 55-15 to over 139 degrees for isolates 55-12 

 and 55-31, table 4. When grown on whole oat grains, isolate 55-52 was not com- 

 pletely destroyed by treatments below 143 degrees, table 5. Only two isolates were 

 subjected to heat treatments for 24 and 48 hours. Isolate 55-52 was destroyed by a 

 treatment at 125 degrees F. in 24 hours. A 48-hour exposure to 120 degrees weak- 

 ened the culture but did not destroy it. Isolate 55-62 was weakened when subjected 

 to 120 degrees for 24 hours and killed at 120 degrees F. in 48 hours. 



Curvularia cultures were more uniform in their tolerance to heat than were 

 Fusarium cultures. All isolates of Curvularia tested were killed in 30 minutes at 

 132 to 04 degrees F. Only two isolates were treated for longer periods and both 

 were killed in 24 hours at 123 degrees, but not at 122 degrees. 



All three isolates of Stromatinia tested were killed in 30 minutes at 124 de- 

 grees F. The three isolates reacted similarly to long-time exposures, being killed 

 in 24 hours at 105 degrees F. 



CORMEL TREATMENTS 



Bald (1956) stated, "Tolerance to high temperatures seems to arise from the 

 initiation of full dormancy by warm growing conditions. Cormels maturing under 

 cool conditions become only partially dormant." He stated further, "The most fa- 

 vorable time for treatment of cormels is about 2 to 4 months after digging. " 



In the winter of 1956-1957 a test was made to determine if there was a time 

 at which Illinois -grown cormels could withstand the hot-water treatment. Cormels 

 of six varieties which had been dug in early October were divided into lots, the corm- 

 els of each variety into six lots. Each lot of a variety contained approximately the 

 same number of cormels. No attempt was naade to use the same size lots for all va- 

 rieties. One lot from each variety was treated in hot water at 135 degrees F. for 30 

 minutes on Novennber 30. This treatment was selected because it is recommended 

 in some gladiolus -growing areas of California and Florida. Subsequent lots were 

 treated December 22, January 31, February 27, and March 27. One lot was left un- 

 treated to serve as a check. The cormels were kept in the laboratory at a tempera- 

 ture of about 75 degrees F. from November 1 until treated. They were kept at 40 

 degrees F. from the time they were treated until May 13, when they were removed 

 to a commercial gladiolus grower's warehouse andkept thereuntil planted on May 23. 



Results of this experiment are shown in table 6. The varieties varied con- 

 siderably in their tolerance to the heat treatments. As indicated by yields of corms 

 from the cormels, none of the varieties withstood the November 30 heat treatments 



