PLANT NEMATODES THE GROWER SHOULD KNOW


perimental work with this group is difficult because of their small size
and their migratory way of life.
 There exist, of course, many other nematode parasites of similar
habits that belong to the same or related taxonomic groups, but the
meadow nematodes are apparently the most destructive and most widely
distributed.


 MISCELLANEOUS TYPES
 Since it would not be possible to mention here all these other types,
 only a few will be listed. Some are known to occur in Florida and other
 southern states. Among them the hoplolaims or lance nematodes espe-
 cially should be mentioned. They appear to be mainly a tropical and
 subtropical group of migratory root parasites. Various species from
 Florida soils are known to us, while farther north only one form, Hoplo-
 laimus coronatus Cobb, as yet has been observed. The lance nematodes
 are stout, cylindrical, rather large-sized parasites with an extremely
 strong buccal stylet, the tail end usually being obtuse and the cuticle
 coarsely annulated. They somewhat resemble the meadow nematodes
 in their life habits and may also occur in large numbers on roots if
undisturbed for considerable periods of time. In combination with other
pathogenic agents and adverse environmental conditions such as drought,
a killing effect by these nematodes has been observed, particularly on
seedling plants. In Florida they have been noticed as pests in forest
nurseries, parasitizing seedlings of Pinus palustris Mill. Often only sur-
face parasites, the hoplolaims may also enter the roots with the whole
body. They are therefore endo- as well as ectoparasites (Fig. 30).
 Other extremely interesting types are the awl nematodes, Dolicho-
dorus heterocephalus Cobb (Fig. 81), and the sting nematode, Belono-
laimus gracilis Steiner, 1949. (Fig. 32). Both are found in Florida and
both feed on roots which they puncture from the surface with their long
needle- or awl-shaped buccal stylets. The former was observed on
celery roots near Sanford. The latter was found on corn roots, also
from Sanford, and on roots of slash and long leaf pine seedlings in
various forest nurseries (Ocala, Brooksville, Valparaiso).
 In recent years much progress has been made (through the work of
J. R. Christie, V. G. Perry, and others) in establishing the wide distri-
bution and the virulence of these and still other ectoparasitic nematodes


 Figure 26.-Paratylenchus elachistus Steiner, 1949, a pin nematode that was
found attacking the roots of ramie (Boehmeria nivea (L.) Gaud.) in the region of
Clewiston, Fla. Material collected by W. D. Wylie, December 1943. A. Female;
cer ppl, cervical papilla; lat fid, lateral field, x 500. B. Head end of female; dsl
oe gl, dorsal oesophageal gland, ampulla outlet; subv oe gl, subventral oesophageal
gland outlet; x 1800. C. Male; phas, phasmid (?); x 500.