Soybean Cyst Nematode Reproduction in the North Central United States.

An experiment was conducted in Heterodera glycines-infested fields in 40 north central U.S. environments (21 sites in 1994 and 19 sites in 1995) to assess reproduction of this nematode. Two resistant and two susceptible soybean cultivars from each of the maturity groups (MG) I through IV were grown at each site in 6.1 m by 4 row plots. Soil samples were collected from each plot at planting and harvest and processed at Iowa State University to determine H. glycines initial (Pi) and final (Pf) population densities as eggs per 100 cm3 of soil. Overall, reproduction (Pf/Pi) of H. glycines on susceptible cultivars in all MG was similar. Reproduction was higher on MG III and IV susceptible cultivars than on those in MG I and II. Resistant MG I and II cultivars reduced nematode population densities more consistently than those in MG III and IV. Reproduction of the nematode was similar among sites within the same maturity zone (MZ), defined as the areas of best adaptation of the corresponding MG. Nonetheless, careful monitoring of nematode population densities is necessary to assess changes that occur over time in individual fields.

Impact of Plant Nutrition on Pratylenchus penetrans Infection of Prunus avium Rootstocks.

A hypothesis that cherry rootstocks grown under optimal nutrient conditions are affected less by Pratylenchus penetrans infection than those grown under deficient nutrient conditions was tested by growing four Prunus avium L. rootstocks ('Mazzard', 'Mahaleb', 'GI148-1', and 'GI148-8') at a soil pH of 7.0 over a period of 3 months under greenhouse conditions (25 ñ 2 degrees C). Pratylenchus penetrans was inoculated at 0 (control) or 1,500 nematodes per g fresh root weight for a total of 3,600, 4,200, 10,500, and 11,400 per plant on Mazzard, Mahaleb, GI148-1, and GI148-8, respectively, with nutrients (commercial fertilizer) applied once at planting (deficient) or twice weekly (optimal). The experiment was repeated once. The optimum nutrient regime resulted in greater soil nutrient levels and plant growth; higher leaf concentrations of N, P, K, and Mg; and fewer P. penetrans than under the deficient nutrient regime. The addition of fertilizer either may increase nematode mortality in the soil or improve rootstock resistance to nematode infection. Increases in Ca in leaves from the nutrient-deficient and nematode-infected treatments suggested the plants were physiologically stressed. The Pf/Pi ratios indicated that these rootstocks may have had resistance to P. penetrans; however, because of the dominant role of nutrition in the experimental design, the question of resistance could not be properly addressed.

A closer look at self-image in male foster care adolescents.

Using the Offer Self-Image Questionnaire, this study attempted to determine the differences between 58 male adolescents in foster care and their peers in the normal population and to establish if there are characteristics of the adolescents' background or foster care experience related to specific domains of self-image. Characteristics from foster care history included number of placements and length of time at the current placement. Individual background characteristics included race, educational achievement, and age. Foster care youths had lower family self-image and emotional health and higher social self-image when compared with the normative population. Lower scores on several domains of self-image were associated with being younger, being white, having lower academic achievement, having more placements, and staying at the current placement for a longer time. The implications of these findings for foster care placement decisions are discussed.

Influence of Heterodera glycines on Interspecific and Intraspecific Competition Associated with Glycine max and Chenopodium album.

The influence of Heterodera glycines (soybean cyst nematode) on the interspecific and intraspecific competition associated with Glycine max (soybean) and Chenopodium album (common lambsquarters) was studied in 1988 and 1989 in three de Wit replacement series experiments in growth chambers and microplots. Glycine max was grown alone (1 plant/experimental unit), in intraspecific competition (2 plants/experimental unit), in interspecific competition with C. album, and in presence or absence of H. glycines. No significant effects of H. glycines and C. album on G. max growth were observed 14 days after planting. By 42 days after planting, both H. glycines and C. album had a negative (P = 0.05) influence on the growth of G. max. Relative crowding coefficients for G. max were lower and deviated (P = 0.05 and P = 0.001) from 1.0 in the presence of H. glycines, compared to that of C. album and early emerged C. album in the absence of the nematode, respectively. Glycine max, therefore, became less competitive than C. album. There was a trend that the presence of H. glycines decreased the competitiveness of G. max on measures of the aggressivity and relative mixture response. Heterodera glycines decreased the aggressivity of G. max (ca. 150-350%) and increased the relative effects of intraspecific interference on G. max (ca. 10-50%) and interspecific interference (ca. 60-350%) after 42 days of plant growth, compared with plants grown in the absence of H. glycines. No H. glycines x C. album interactions were detected. Observations showed that H. glycines and early emerged C. album inhibited the growth of G. max 5-13%, as measured by plant dry weight.

Impact of Multi-year Cropping Regimes on Solanum tuberosum Tuber Yields in the Presence of Pratylenchus penetrans and Verticillium dahliae.

Five cropping regimes involving combinations of 2 legumes, alfalfa (Medicago sativa) and yellow sweet dover (Melilotus officinalis), 2 monocots, corn (Zea mays) and sudax (Sorghum halupeuse x Sorghum sudanese), and potato (Solanum tuberosum cv. Superior) were tested for their impact on potato yields in a field infested with Pratylenchus penetrans and Verticillium dahliae. No differences in 1990 tuber yields were observed among the five cropping regimes (P < 0.05). In 1991, yields following 1 year of corn, sudax, sweet clover, or alfalfa and 2 years of potato were not different from that of 3 years of continuous potato (P < 0.05). Two years of sweet clover or alfalfa followed by potato resulted in significantly increased potato tuber yields compared with 3 years of potato (P < 0.05). The 2-year legume and 2-year grain rotations resulted in lower P. penetrans population densities at the end of the 3-year rotation compared with 3 years of continuous potato (P < 0.01). The highest preplant V. dahliae population density (34 cfu/g soil), together with a P. penetrans density of 12/100 cm(3) of soil was in the sudax-sudax-potato cropping regime and resulted in the lowest potato tuber yield. The highest preplant P. penetrans population density (54/100 cm(3) soil), together with a V. dahliae population density of 19.5 cfu/g soil was observed in the corn-corn-potato cropping regime and resulted in the second lowest potato tuber yield in 1991. After 3 years, potato tuber yields were negatively related to preplant densities of V. dahliae (r(2) = 0.237), P. penetrans (r(2) = 0.175), and both pathogens (r(2) = 0.380). A comprehensive regression model was developed to isolate pathogen effects on potato yields from cropping regime effects encompassing all 10 cropping regimes (r(2) = 0.915).

Plant and soil nematodes: societal impact and focus for the future.

Plant and soil nematodes significandy impact our lives. Therefore, we must understand and manage these complex organisms so that we may continue to develop and sustain our food production systems, our natural resources, our environment, and our quality of life. This publication looks specifically at soil and plant nematology. First, the societal impact of nematodes and benefits of nematology research are briefly presented. Next, the opportunities facing nematology in the next decade are outlined, as well as the resources needed to address these priorities. The safety and sustainability of U.S. food and fiber production depends on public and administrative understanding of the importance of nematodes, the drastic effects of nematodes on many agricultural and horticultural crops, and the current research priorities of nematology.

Plant-parasitic Nematodes Associated with Cherry Rootstocks in Michigan.

In two field trials, 10-year-old sweet and tart cherry rooted on 'Mazzard', 'Mahaleb', 'MXM 2', 'MXM 14', 'MXM 39', 'MXM 60', 'MXM 97', and 'Colt' showed 10-203 Pratylenchus penetrans per g fresh root from all tart rootstocks, and up to 46 Pratylenchus, Criconemella, and Xiphinema spp. per 100 cm(3) soil. Infestation of soil containing 1-year-old Mazzard, Mahaleb, MXM 60, 'GI148-1', and 'G1148-8' with 625/100 cm(3) soil of either P. penetrans or C. xenoplax resulting in final nematode population densities of 123-486 and 451-2,496/g fresh root plus 100 cm(3) soil, respectively, and had little effect on plant height or dry weight after 157 days in a greenhouse. Population densities of neither nematode differed among the five rootstocks. In a second greenhouse experiment, soil containing the same rootstocks was infested with P. penetrans (1,250/100 cm(3) soil), maintained for 8 months in a greenhouse, 4 months in a cold room (2-4 C), and 3 additional months in a greenhouse. The number of P. penetrans recovered at the end of 475 days was approximately 10% of those recovered in the first experiment, probably due to the cold treatment. The ability of P. penetrans and C. xenoplax to infect the cherry rootstocks may be of concern in cherry management programs.

Influence of Irrigation and Heterorhabditis bacteriophora on Plant-parasitic Nematodes in Turf.

Daily irrigated, 80% pan replacement, and nonirrigated field plots of Kentucky bluegrass (Poa pratensis L.) were inoculated with a mixture of Steinernema carpocapsae (All strain) and Heterorhabditis bacteriophora (HP-88 strain) in 1988. In 1989, daily irrigated and nonirrigated plots were inoculated with HP-88 alone. The turf and associated soil contained populations of Tylenchorhynchus dubius, T. nudus, Pratylenchus penetrans, Paratylenchus projectus, and Criconemella rustica. In irrigated plots in 1988, population densities of Tylenchorhynchus spp. were lower in plots inoculated with HP-88 plus All compared with that in control plots. The same effect was absent under nonirrigated conditions. In 1989, population densities of Pratylenchus penetrans associated with inoculated turf were lower than those recovered from noninoculated turf in irrigated but not under nonirrigated conditions. Population densities of plant-parasitic nematodes were generally higher in the irrigated compared with the nonirrigated environment.

Distribution of Heterodera carotae and Meloidogyne hapla in Michigan Carrot Production.

During 1986 and 1988, selected farms in all of the major carrot-growing counties of Michigan were surveyed to determine the extent of infestation by Heterodera carotae and Meloidogyne hapla. Both species were found in all eight counties surveyed, but not on all farms. Heterodera carotae was recovered from 67.4% of the fields surveyed. Meloidogyne hapla was detected in 24.8% of the samples and from 69.8% of the fields. In most cases, H. carotae and M. hapla occurred in the same field.

Semi-quantitative assay of D antigen site density by flow cytometric analysis.

This study describes the comparative measurement of D antigen site density using a fluorescent indirect antiglobulin test (FIAT) read by flow cytometry. The test results confirmed the continuum of D antigen strength from weakest D through to R2R2 and also allowed the majority of weak D samples to be adequately distinguished from D-negative samples.

Descriptions and Comparative Morphology of Cactodera milleri n. sp. (Nematoda: Heteroderidae) and Cactodera cacti with a Review and Key to the Genus Cactodera.

A new species, Cactodera milleri n. sp., is described and illustrated from specimens obtained from roots of common lambsquarter, Chenopodium album L., from Mattawan, Michigan. Cactodera milleri can be differentiated from other Cactodera species by the presence of punctated egg shells and a second-stage juvenile (J2) stylet length averaging 21.8 mum as measured from freshly killed specimens in water mounts. Thirty-four plant species, including 11 weed species, 18 agronomic crop species, and 5 cactus species were tested as potential hosts of C. milleri. The new species reproduced only on Chenopodium album, C. amaranticolor Cofte. Reyn., and C. quinoa Willd. Cactodera cacti (Filipjev &Schuurmans Stekhoven, 1941) Krall &Krall, 1978, a morphologically similar species, is reexamined. A description of the female and additional morphometric and morphologic data of cysts, males, J2, and eggs are provided for several populations of C. cacti. A review of the morphometrics of all species of Cactodera and a taxonomic key to the seven species are presented.

Characterization of a neuraminidase from Corynebacterium aquaticum responsible for Th polyagglutination.

Th polyagglutinability is characterized by the agglutination of the red blood cells (RBC) by Arachis hypogaea, Medicago disciformis, Vicia cretica but, in contrast to the T phenomenon, not by Glycine max (Glycine soja). Because Th transformation of RBC has been obtained in vitro, the mechanism of Th polyagglutinability expression has been studied and reproduced experimentally. An enzyme with neuraminidase specificity has been isolated from the culture supernatant of Corynebacterium aquaticum, and further characterized (MW = 55,600 kDa, pH = 5.5, Km = 0.138 microM, Kcat = 0.22 micrograms). Reversely, Th transformation of RBC could be obtained by using other neuraminidases but in very mild conditions of hydrolysis. From our results, it can be concluded that by the release of less than 20 micrograms of sialic acid per 10(10) RBC, Th reactivity can be induced whereas hydrolysis of greater amounts of sialic acid (greater than 20 micrograms/10(10) RBC) give the classical T polyagglutinability.

Enhanced reaction with Vicia graminea lectin and exposed terminal N-acetyl-D-glucosaminyl residues on a sample of human red cells with Hb M-Hyde Park.

A sample of polyagglutinable red cells was obtained from a healthy individual (group O, N) possessing a hemoglobin (Hb) variant called Hb M-Hyde Park. The sialic acid content of the individual's red cells is 90 percent of normal, and his cells are agglutinated by monoclonal but not lectin anti-Tn, a panel of lectins specific for N-acetylgalactosamine (or galactose), and N-acetylglucosamine. Enhanced agglutination reactions were obtained with Vicia graminea, Ulex europaeus, and human anti-I and -i. Using various enzyme treatments and different methods of labeling cell surface components, two defective cell membrane sites have been identified: one associated with the O-linked oligosaccharides on sialoglycoproteins and the other associated with exposed N-acetylglucosaminyl residues located on membrane components of apparent molecular weights 88,000 to 130,000 and 46,000 to 73,000 (probably the Band 3 and Band 4.5 regions, respectively).