8 MISC. PUBLICATION 4 6, U. S. DEPT. OF AGRICULTURE 



GENERALIZED REPORTS BY PLANT GROUPS 



Whole groups of related plants do not as a rule show uniform 

 behavior toward root knot infestation, yet generalizations have been 

 made. Grains and grasses are commonly accepted as resistant; 

 writers of bulletins have quoted each other to this effect in a continu- 

 ous series, but — far from adding any species to those named by 

 Bessey (16) — few workers have recorded any original observations of 

 resistance in particular species. When grasses are found infested, 

 on the other hand, the fact is almost invariably reported. This 

 results in a lack of balance in the citations under certain species, in 

 that instances of infestation have been reported more often than 

 instances of resistance. Other grasses, undoubtedly resistant, have 

 never specifically been so reported and are thus not listed at all. 

 Again, there are no reports on any species of fern, yet ferns are possibly 

 as nearly immune as any plants can be. Thus there are certain data 

 that can best be presented in a group arrangement. 



Filicineae, ferns. 



Christie, J. R. (Division of Nematology, Bureau of Plant Industry. 1938): 

 Ferns are probably as nearly immune as any plant. 



Steiner, G. (Division of Nematology, Bureau of Plant Industry. 1939): 

 Never found nor reported infested. 



Stone and Smith. 1898 {224)'. Ferns are listed among greenhouse plants 

 "attacked by nematodes." [Although root knot is the subject of the 

 bulletin, this statement, from whatever source, refers undoubtedly to 

 the fern-leaf nematode, Aphelenchoides jragariae (Ritzema Bos) Christie 

 (syn. Aphelenchus olesistus Ritzema Bos).] 



Taxaceae, yew family, and Pinaceae, pine family. 



Hume 1937: 5 Harmful infestation never found on the commonly grown 

 conifers, including Chamaecyparis, Juniperus, Pinus, and the Taxaceae. 

 Florida. 

 "Young, V. H. (Arkansas station; in letter, 1937): Coniferous stock seems 

 to show no galls. 



The only conifers so far reported infested are Cedrus, Chamaecyparis, Juniperus 

 (only one report each), and Pinus (q. v.). 



Gramineae (Poaceae), grass family. 



Baker 1910 (5): Millet is easilv grown on the worst infested soils. Brazil 

 (Para). 



Balachowsky and Mesnil 1935 (6) : Cereals are resistant when they have 

 more than four leaves. [Question: To what nematode? These authors 

 claim to have seen root knot on wheat, but they have included under 

 Heterodera marioni, without reference to authorities, citations dealing 

 with H. schachtii Schmidt, the sugar-beet nematode (see Avena and 

 Hordeum), and they describe symptoms for cereals that suggest other 

 nematode diseases (see final paragraph under Avena) .] 



Bessey 1911 (16): Many of the grasses seem to be resistant. 



California Nematode Committee 1925: 6 Cereals resistant. 



Cobb 1890 {89): The cereals generally are "but little affected." 



Fikry 1939 (64) : Grasses are attacked throughout the Nile Valley. Egypt. 



Frank 1885 (68): Infestation conspicuously absent from all cereals; other 

 hosts preferred (one planting). Germany. [The fact that the potato 

 plants and the Cruciferae tested weie also conspicuously free from 

 infestation throws considerable doubt on the uniformity of infestation 

 in the test plot.l 



Georgia Coastal Plain Experiment Station 1936 (83): In 3-year rota- 

 tions for tobacco growing, bull grass (Paspalum boscianum) has been 

 observed to be very susceptible; tobacco has failed, because of root knot, 

 following this weed; crabgrass, Sudan grass, carpet grass, and Bermuda 

 grass are also susceptible but to a lesser degree. 



5 See discussion of host plants by H. Harold Hume on p 118 of reference given in footnote 3, p. 6. 

 « California Agricultural Experiment Station. Nematode Committee. Unpublished data. 

 11925?! 



