Population Development and Influence of Bursaphelenchus xylophilus on Gliocladium virens.

Gliocladium virens was isolated from slash pine trees symptomatic and asymptomatic for pine wilt disease with frequencies of 24% and 10%, respectively. Populations of Bursaphelenchus xylophilus, the nematode incitant of this disease, reproduced on this fungus and inhibited its growth. Growth inhibition of the fungus was characterized by an absence of sporulation and by the formation of chains of dark, thick-walled, chlamydospore-like cells. Population increase during a 12-day period following infestation of cultures of the fungus with 10,000 nematodes averaged 3-fold at 16 C, 9-fold at 20 C, and 24-fold at 24 C. In greenhouse studies, nematode recovery from slash pine seedlings coinoculated with both organisms was significantly greater than that obtained from seedlings inoculated with the nematode alone.

Resistant Germplasm in Gossypium Species and Related Plants to Rotylenchulus reniformis.

Gossypium hirsutum, G. herbaceum, G. arboreum, G. barbadense, wild Gossypium spp., Hibiscus spp, and other Malvaceae were tested in the greenhouse to identify germplasm resistant to Rotylenchulus reniformis (Rr). Host resistance was based on Rr egg production per gram of root compared with known G. hirsutum susceptible 'Deltapine 16' as check. G. longicalyx and Sida rhombifolia were nonhosts. High levels of resistance were found in G. stocksii, G. somalense, and G. barbadense 'Texas 110.' Other cotton lines with potential value in breeding for Rr resistance were G. herbaceum P.I. 408775; G. arboreum P.I. 41895, P.I, 417891, CB 3839; and G. hirsutum 893. All these supported less than 20% of the egg production on the check. Seventy-three percent of the Hibiscus spp. tested were resistant. Female development and egg production reflected host resistance; healthy females and large egg masses were observed on susceptible plants, and degenerated females and small egg masses on resistant plants. Females penetrating nonhost G. longicalyx never matured to kidney shape.

Observations on the Morphology of the Pine Wood Nematode, Bursaphelenchus xylophilus.

Scans of slash pine wood chips infested with pine wood nematodes showed coiled aggregates of 5-10 nematodes in the axial resin canals, and 1-2 nematodes folded in the radial resin canals. Observations of the pine wood nematode by SEM showed the head to be offset with six labial lobes. A smaller circle of six inner lobes surrounded the stoma. A single labial sensillum was observed on each of the two subventral and two subdorsal lobes. The two opposite lobes, without sensilla, bore a pore-like amphid. The female vulva flap was observed to be a pouch. In addition to two pairs of copulatory papillae previously described for the male, three additional papillae were observed: an additional post-anal pair, and a single papilla anterior to the cloaca. Spicules were fused ventrally. Distal spicule ends terminated in two fused half discs. Caudal alae were angular at the tail terminus, but culed inward at the corners to appear oval. Lateral fields had four lateral striations.

Scanning electron microscopy of perineal patterns of three species of Meloidogyne.

The perineal pattern of Meloidogyne graminicola is oval, characterized by the anastomosing of cuticular striae converging, and elevating at the tail terminus. A deep lateral incisure forming a low arch traverses the rounded perineal pattern of Meloidogyne hapla. Punctations at the tail region of M. hapla are not observed with the scanning electron microscope. Minute crosslines invaginate with the vulvar lips of Meloidogyne incognita. Punctate indentations around the anal opening and bordering the lateral sides of the vulvar slit of M. incognita are revealed.

Meloidogyne incognita wartellei n. subsp. (Meloidogynidae), a Root-knot Nematode on Resistant Soybeans in Louisiana.

Meloidogyne incognita wartellei n. subsp, is described and illustrated from roots of soybean (Glycine max L.) near Washington, Louisiana. It is rather limited in distribution in that state, being known at five locations comprising about 60,000 acres. It not only attacks commonly susceptihle soybeans but is a destructive pest on other commercial soybean varieties that are resistant to other forms of the M. incognita group in the area. This new subspecies is related most closely to M. i. incognita and M. i. acrita, but differs especially in the females having a delicate stylet with small, rounded knobs sloping posteriorly; dorsal esophageal gland orific further back (5 mum) from base of stylet; and excretory pore often two to three stylet lengths (sometimes more) from the anterior end. Also, males are often without detectable head annules and with an average stylet length of 22.4 mum. Comments and morphometric data are given on M. i. incognita and M. i. acrita.

Heterodera graminophila n. sp. (Nematoda Heteroderae) from Grass with a Key to Closely Related Species.

Heterodera graminophila n. sp., a member of the H. goettingiana group, is described and illustrated from roots of barnyard grass, Echinochloa colonum (L.) Link, in Baton Rouge, La. This new abullate species, having second-stage larvae with only three lines in the lateral field, is most closely related to H. cyperi Golden, Rau &Cobb, 1962, and H. graminis Stynes, 1971, but differs particularly in having a small, inconspicuous anus without a circum-anal pattern and located about 20% of the cyst length from the vulval cone terminus, and a longer vulval slit averaging 45 mu in length. A key, based on cyst and larval characters, is presented for identification of the 10 Heterodera species in the H. goettingiana group.