PRELIMINARY TEST 



A preliminary test on survival of hot-water -treated Illinois -grown cormels 

 was made in 1956 on a commercial gladiolus grower's farm in Kankakee County, 

 Illinois. The cormels were treated in a specially built insulated treating tank with 

 temperatures of circulating water thermostatically controlled within 0.5 degree F, 

 of the desired temperature. Because the equipment was not ready to use until after 

 mid-June, the treatments were not made as early as had been intended. Cormels 

 were treated June 20 and 11 and planted June 22. The following treatments were 

 used on cormels of the gladiolus varieties Debonair, Spic and Span, and Margaret 

 Fulton: hot-water at 131 degrees for 30, 45, and 60 minutes; hot-water at 125 degrees 

 for 4 hours; hot-water at 135 degrees for 10, 20, and 30 minutes; New Improved 

 Ceresan, one -half pound in 25 gallons of water at air temperature for 1 hour. An 

 additional treatment in water at 110 degrees for 23 hours was used on one variety. 

 One 1 -pound coffee can, level full, of cormels was used as a treatment lot. Sixteen 

 feet of row were used for planting each lot of cormels. Results of this test are shown 

 in tables 1, 2, and 3. 



Although germination was reduced by the heat treatments and there was a pro- 

 gressive reduction in germination as temperatures andtreating times were increased, 

 in none of the lots were all of the cormels destroyed by the hot-water treatments. 

 Since the cormels were probably far out of their dormancy at the time of treatment, 

 the results were not discouraging. As the cormels were planted in a field where 

 diseased gladioli had been present, little significance can be attached to the amount 

 of rot which developed in the various lots. 



HEAT TOLERANCES OF GLADIOLUS PATHOGENS 



In the winter of 1956-57 laboratory tests were conducted on heat tolerances 

 of gladiolus pathogens. These tests were carried out with the help of Raymond E. 

 Wilken, then Technical Assistant, Illinois Natural History Survey. Cultures of 

 Fusarium oxysporum f. gladioli (Massey) Snyd. Si Hans. , Curvularia trifolii (Kauffm.) 

 Boed. rr'gladioli Parm. h. Lutt. , and Stromatinia gladioli (Drayton) Whet., which 

 had been isolated originally fronn diseased tissues of gladiolus corms, were subcul- 

 tured on potato dextrose agar in petri dishes and incubated at 24 degrees C. Fusarium 

 and Curvularia cultures were incubated 10 days and Stromatinia cultures 2 weeks 

 before being used in the heat tolerance tests. Twenty-six isolates of Fusarium , 12 

 isolates of Curvularia, and 3 isolates of Stromatinia were used in the tests. Alto- 

 gether 270 individual tests were made. 



The various isolates of the three organisms were subjected to a series of heat 

 treatments in which the following procedure was used for each test: Six test tubes, 

 each containing? ml. of distilled water, were suspended in an automatic Fisher con- 

 stant temperature bath, fig. 1. All tubes were allowed to reach a preselected tem- 

 perature before inoculum was added. The petri dish subculture of the organism to 

 be tested was dispersed for 30 seconds in a Waring Blendor containing 200 ml. of 

 distilled water. Five drops of the dispersed culture were then added to each of the 

 six tubes in the water bath. At the end of each of three periods, (15, 30, and 60 

 minutes) one pair of test tubes was removed from the water bath and the contents of 

 each tube was poured into a petri dish containing potato dextrose agar. After the 

 dishes had stood for a few seconds to allow the solid particles to settle, the water 

 was poured off. Checks were prepared by adding five drops of the dispersed culture 

 to 7 ml. of water in a test tube, shaking the tube for a few seconds, and then pouring 

 the contents into a petri dish containing potato dextrose agar. After the solid parti- 



