Res. (Keloid. ):Ii 



This paper also raises another question concerning the necessity for 

 absolute or extremely high root-knot resistance. In field crops where 

 small increments of tolerance may be economically valuable it may be 

 wiser to utilize the best resistance available in readily accessible 

 material rather than delay improvement until high resistant or immiine 

 sources of resistance are located which may be difficult to transfer. 



Slides were shown giving results of studies on root-resistance in 

 commercial cotton varieties and the relation of this resistance to 

 Fusarium wilt and yield. Root-knot resistance is positively correlated 

 with Fusarium resistance and yield on heavily infested soils. By the 

 use of soil fumigants in row applications the difference in yield on 

 treated and untreated soils gave an indication of total nematode resist- 

 ance. It was shown that Auburn 56, a cotton variety developed at the 

 Alabama Experiment Station by Mr. H. B. Tisdale, was outstanding in 

 root-knot and wilt resistance in comparison with other varieties. 



Discussion 



In a discussion of root-knot resistance breeding with tomatoes, Dr. Al 

 Harrison from Toaloim, Texas, stated that very high resistance to 

 Meloidogyne species had been obtained in combination with resistance 

 to Fusarium and some other diseases. North Carolina workers praised 

 Dr. Harrison for developing this material and stated that in the North 

 Carolina test his material appeared almost commercial in type. 



Dr. Holdeman raised the question of the possibility of the occurrence 

 of races id.thin the several species of root-knot created by Dr. Chitvood. 

 He pointed ovt that most workers have tested their breeding material 

 using the Ox-iginal isolates made by Dr. Sasser as representative of 

 Chitwood's species. Dr. Holdeman reported that Dr. Hartwig was supply- 

 ing the seed of 2$ soybean varieties to a number of people across the 

 Southeast to get a regional measure of root-knot resistance in these 

 varieties and to determine whether different strains could be foiond in 

 the root-knot species involved. 



The finding of a good source of root-knot resistance in tobacco was 

 reported. Resistance was found determined by a single dominant gene 

 which was not deleterious to yield, and it was anticipated that rapid 

 progress would be made in developing resistant varieties. (Other 

 discussion not recorded) 



