PLANT NEMATODES THE GROWER SHOULD KNOW


 There exist other sedentary root parasitic nematodes which in con-
trast with the foregoing groups have preserved a certain, though reduced,
motility; they are called ring and scale nematodes and include various


 Figure 23.-A ring nematode (undescribed species) attacking the root of a
pummelo (Citrus grandis) grown in a greenhouse at the Plant Industry Station,
Beltsville, Md. Its head is buried in the root surface; several nearby surface cavities
were probably made by the same nematode; x 75.

 Figure 22.-Two different types of ring nematodes. A. Criconemoides citri
Steiner 1949, representing a broadly annulated type, infecting roots of the sour
orange in the region of Orlando, Fla. The roots are punctured from the surface with
the remarkably strong buccal stylet and the head itself is frequently buried deep
in the root tissue which becomes necrotic around the organism. B. Criconema ci-
vellae Steiner 1949, representing a very unusual type of nematode with its 8 longi-
tudinal series of fringed scale-like structures on the body surface. It was found
feeding on the roots of Citrus grandis (L.) Osbeck, the pummelo, grown in a
greenhouse of the Plant Industry Station, Beltsville, Md.