ROOT KNOT NEMATODE INFESTATION 49 



Oak, see Quercus. 



Oat, see Avena. 



Oatgrass, see Arrhenatherum. 



Oenothera lamarckiana, lamarck evening-primrose. 



Goff 1936 (96): No infestation found (25 plants, 1 test). Florida. 

 Onion, see Allium. 

 Opuntia spp., pricklypear. (N) 



Grower: Vigorous; not injured by infestation. California. 

 Orange, see Citrus and Poncirus. 

 Orchard grass, see Dactylis. 

 Ornithopus sativus, serradella. (C) 



Bessey 1911 (16): Nematodes not abundant and no injury observed. 



Frank 1885 (68) : Galls numerous. Germany. 



Orthosiphon bracteosus. 



Collins (4D: No signs of nematode attack (1937); weed host (1938). 

 Rhodesia. 



Oryza sativa, rice. (C, N) 



Barber 1901 (9): Paddy recommended as an "immune crop." India 

 (Madras). 



Fajardo and Palo 1933 (60): Rice fields kept under water for 2 to 4 

 months are usually free, /n upland variety, "Dumali" (native name), 

 was rated as resistant; 10 plants infested, 30 plants free. Philippine 

 Islands. 



Krishna Ayyar 1933 (132): No infestation found in pot experiment. India 

 (Madras). 



Rolfs 1907 (201): "Almost quite immune." 



Steiner 1934 (222): The rice plant (Var. Supreme Blue Rose) suffers more 

 than numerous other hosts because root tips are blinded and infested 

 tissues break open. Arkansas. 



Ttjllis 1934 (285): Plants yellow and dwarfed in the field; heavy experi- 

 mental infestation on Var. Supreme Blue Rose; infested roots reduced in 

 number and in length; more nematodes in the submerged than in the 

 nonsubmerged roots. Arkansas. 



Pachyrhizus angulatus. 



Beeley 1939 (14)' Infestation apparently not observed [Malaya?] nor 

 reported [in literature?]; experiments projected. 



Pachyrhizus erosus, yam-bean. (N) 



Fajardo and Palo 1933 (60): Rated as "resistant"; 45 plants infested, 20 

 plants free. Philippine Islands. 



Paeonia hybrids, peony. (N, S) 



Brown 1929 (25): Infested roots received for examination have not included 



any of the officinalis group. 

 Buhrer 1938: 87 P. officinalis listed as a host plant. [Data from Bureau of 



Entomology and Plant Quarantine; infested shipments intercepted from 



three different European countries.] 

 Nelson 1926: 88 P. officinalis Var. "Rosea" especially "affected." Michigan 



(in nursery). 

 1931 (177): There appears to be little if any varietal resistance in P. 



albiflora, Chinese peony. Michigan. 

 S., 1928 (206): Heavy-growing varieties with big roots, like Festiva Maxima, 



seem to thrive in spite of the nematodes; less vigorous varieties suffer 



severely. Missouri. [Bailey's Standard Cyclopedia of Horticulture 



(1935) names Var. Festiva under both common species, P. albiflora and 



P. officinalis.} 



87 Buhrer, Edna M. additions to the list of plants attacked by the root-knot nematode 

 (heterodera marioni). U. S. Bur. Plant Indus., Plant Dis. Rptr. 22: 216-234. 1938. [Mimeographed.] 



88 Martin, G. Hamilton, diseases of forest and shade trees, ornamental and miscellaneous 

 plants in the united states in 1925. U. S. Bur. Plant Indus., Plant Dis. Rptr. Sup. 50, pp. 413-478, illus. 

 1926. [Mimeographed.] See report of Nelson, p. 461. 



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