ROOT KNOT NEMATODE INFESTATION 77 



Tyler 1938: 62 Mexican zinnias possibly somewhat resistant (experimental, 



in greenhouse). District of Columbia. 

 Watkins 1929 {248): Zinnia rated as "resistant." Florida. 



Zizyphus jujuba, common jujube. (C) 



California Nematode Committee 1925: 63 Resistant. 



Georgia Coastal Plain Experiment Station 1935 (80): "Jujubes have 

 been growing in the trial grounds 12 years, have produced 11 consecutive 

 crops of fruit, are as yet free from insect and disease attack" [nematodes 

 not mentioned]. 



SUMMARY 



It is impossible at present to draw lines between high resistance, 

 moderate resistance, and tolerance. All possible gradations and com- 

 binations of qualities are found ; there are even occasional instances of 

 heavy and conspicuous infestation on some of the most resistant plants. 

 For the benefit of growers the following tentative list of plants that 

 now appear most highly resistant is given. Even this carefully culled 

 selection is arbitrary and subject to revision as additional information 

 becomes available. A comparative testing of all these plants would 

 be of great value. The reports cited in this compilation are in no 

 way considered final. 



Plants Usually Recommended to Growers as Resistant to 



Root Knot 



Amygdalus persica : certain selections of Shalil and Yunnan peaches and P. I. No- 



61302 (peach X nectarine). 

 Avena sativa, oat. 



Citrus spp., grapefruit, lemon, orange. 

 Crotalaria spectabilis. 



Desmodium tortuosum, Florida beggarweed. 

 Lanlana camara, common lantana. 

 Malus sylvestris, apple. 

 Narcissus spp., narcissus. 

 Panicum miliaceum, broomcorn millet. 

 Panicum purpurascens, Para grass. 

 Pennisetum glaucum, pearl millet. 

 Phleum pratense, timothy. 

 Prunus armeniaca, apricot. 

 Prunus cerasus, sour cherry. 

 Prunus hortulana, hortulan plum. 

 Prunus mume, Japanese apricot. 

 Prunus munsoniana, wildgoose plum. 

 Prunus hybrid, Marianna plum. 

 Rhododendron spp., azalea and rhododendron. 

 Ribes spp., currant and gooseberry. 

 Secale cereale, rye. 

 Senecio cineraria, dusty-miller. 

 Sorghum vulgare, sorghum. 

 Stizolobium deeringianum, velvetbean. 

 Tagetes erecta, African marigold and other species. 

 Tulipa spp., tulip. 



Vitis champinii, Var. Dog Ridge (Champin grape). 

 Vitis doaniana, Var. Salt Creek (Doan grape). 

 Ferns are assumed to be highly resistant. 



62 See report of Tyler on p. 140 of reference given in footnote 4, p. 6. 

 fi 3 See footnote 6, p. 8. 



