Heterodera glycines
Soybean cyst nematode
Ichinohe, 1952
SEM Photo Gallery- Nebraska soybean
SEM Photo Gallery- South Dakota corn
Photo Gallery- Cysts

Females lemon-shaped, bearing the subcrystalline layer.  They pass through a pale yellow stage before developing into a dark brown cyst.  Rugose pattern a series of short, zigzag lines without order.  Punctations of cuticle fine, irregularly arranged.  As many as 200 eggs may be deposited in the egg-sac.  Vulva averaging 49.7 u (43 to 56) long.   Bullae present.
    Males 1.3 mm (1.1 to 1.4) in length, closely resembling those of other Heterodera.  Spear knobs massive, rounded.  Cephalids located dorsally and ventrally near the sixth and eighth annules.  Esophageal gland nuclei about one body width apart.  Spicula bidentate.  Hemizonid about six annules anterior to excretory pore.
     Second-stage larvae avarage 439.6 (373 to 490) u long.  Cephalids near middle of head.  Spear knobs slightly rounded.   Hemizonid adjacent to excretory pore.  Dorsal esophageal gland opening 4.0 (3.3 to 5.2) u behind spear base.  About half of tail length occupied by the hyaline portion.

Symptoms:  Premature yellowing of the foliage on infested area usually is the first obvious evidence of lethal populations of the nemas, but previous to yellowing it is possible to locate the areas by the reduced size and untrifty-appearing plants.
     During years of abundant moisture and on fertile soil, soybeans may produce an almost normal crop while harboring enormous numbers of nematodes.  This is especially true of crops following rotations.  Under these conditions there is a tremendous build-up of the pest.
(Description- Thorne, 1961)

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