Effect of Simulated Acid Rain on Bursaphelenchus xylophilus Infection of Pine Seedlings

White, Scots, and Austrian 3-year-old pine seedlings were treated with conditions simulating acid rain and inoculated with the white pine specific pathotype of Bursaphelenchus xylophilus, VPSt-1. Oleoresin concentration increased slightly and carbohydrate concentration decreased in all seedlings treated with simulated acid rain (SAR). The changes were significantly increased after inoculation of SAR-treated white and Scots pine seedlings with VPSt-1. Wilting was delayed and nematode reproduction decreased in SAR-treated white pine seedlings inoculated with VPSt-1. SAR-treated Austrian pine seedlings were resistant to VPSt-1, but SAR-treated Scots pine seedlings lost tolerance to VPSt-1 and wilted 50-60 days after inoculation.

Carbohydrate Concentration in Pine as Affected by Inoculation with Bursaphelenchus xylophilus

Pines responded to inoculation with Bursaphelenchus xylophilus by changes in reducing and nonreducing carbohydrate concentrations dependent on the pine species and the pathotype of B. xylophilus with which the trees were inoculated. Carbohydrate concentrations, in compatible pine-nematode pathotype combinations, decreased initially after inoculation and then increased slightly before decreasing to approximately 10% of the control levels as the seedlings wilted. In compatible nematode pathotype-pine species combinations, carbohydrate concentrations decreased and then increased as the nematode population densities declined.

Varietal Response and Estimates of Heritability of Resistance to Meloidogyne javanica in Carrots

With methods developed in this study, varietal responses to M. javanica were evaluated and heritability of resistance of two promising carrot cultivars was estimated. More egg masses were found on root systems inoculated with eggs added to the soil in three holes in 250 cm(3) cups than by mixing the inoculum with soil in the cups. A resistant breeding line, CNPH 1437, was discriminated from susceptible cultivar Nova Kuroda with inoculum levels higher than 2,000 eggs per cup. Greenhouse and field results suggested that cultivars Nantes Superior and Shin Kuroda were susceptible, Kuronan was somewhat tolerant, and Brasilia and Tropical were resistant to M. javanica. Nantes Superior or Shin Kuroda yielded less in carbofuran-treated soil (3 kg a.i./ha) than Kuronan, Brasilia, and Tropical did in nontreated soil. However, incorporation of the nematicide greatly increased yields of Kuronan (32%), Brasilia (62%), and Tropical (91%). Primary root galling at the seedling stage was an adequate parameter for resistance evaluation. Estimated heritability were 0.48 +/- 0.07 for primary root galling and 0.35 +/- 0.08 for egg mass production in Brasilia, and 0.16 +/- 0.11 for primary root galling and 0.31 +/- 0.09 for egg mass production in Kuronan.

Morphometrics, Illustration, and Histopathology of Sphaeronema rumicis on Cottonwood in Utah

The morphology of a population of Sphaeronema rumicis Kir'yanova found on cottonwood in Utah is illustrated by light and scanning electron micrographs, as well as by drawings. This is the first report of males of S. rumicis, a species also not known previously to occur in North America. S. rumicis females on cottonwood in the United States were smaller than those found by Kir'yanova on sorrel in the USSR. Females and second-stage juveniles (J2) from the United States had slightly shorter stylets than did females and J2 from the USSR. Males were vermiform and had degenerate esophagi. On secondary cottonwood roots S. rumicis induces formation of a syncytium originating from proliferated pericyclic cells. Thick outer walls, wall protuberances, absence of cell wall ingrowths, dense cytoplasm, and hypertrophied nuclei were the main characteristics of syncytia observed in S. rumicis-infected cottonwood roots.

Cactodera eremica n. sp., Afenestrata africana (Luc et al., 1973) n. gen., n. comb., and an Emended Diagnosis of Sarisodera Wouts and Sher, 1971 (Heteroderidae)

Systematic contributions to Heteroderidae include description of Cactodera eremica n. sp., an emended diagnosis of Sarisodera Wouts and Sher, 1971, and proposal of a new genus and new combination, Afenestrata africana (synonym Sarisodera africana Luc et al., 1973). Cactodera eremica, from the roots of shadscale in Utah, most closely resembles Cactodera thornei (Golden and Raski, 1977) but differs by the presence of a finely striated cuticle, a fine surface pattern on eggs, a shorter female stylet, distance of the DGO from the stylet, vulval slit, and smaller diameter of circumfenestra, as well as a shorter tail in second-stage juveniles. The response of the host to C. eremica is similar to other Heterodera sensu lato including a large syncytium with wall ingrowths. The diagnosis of Sarisodera is emended to exclude cysts, which do not form in the type species, S. hydrophila. Afenestrata africana differs from S. hydrophila by the formation of cysts, the dorsal position of the anus in females, the shorter stylet, and a pore-like phasmid opening in second-stage juveniles. In addition, the lip pattern of males and juveniles is characterized by a greater degree of fusion of lip parts, the host response is a syncytium (versus a single uninucleate giant cell in S. hydrophila), and the cuticle is thinner and lacks a D layer. Unlike Heterodera, the cyst of Afenestrata lacks fenestrae.