Nematode community structure in dogwood, maple, and peach nurseries in Tennessee

Tennessee nurseries are major suppliers of ornamental and fruit trees, but the potential for nematode-induced losses is poorly known. This study was undertaken to i) compare populations of nematode trophic groups in dogwood, maple, and peach nurseries; ii) identify and determine the diversity of of plant parasitic nematodes in these areas; iii) determine the relative importance of tree species and age class, weed cover, and edaphic factors in the distribution of plant parasitic species. Ninety-two nursery blocks were sampled for nematodes in March, July, and October, 1981. Each soil sample was analyzed for pH, bulk density, texture, and organic matter content. Nematodes were extracted from a 200 cm3 aliquant of each sample and counted. Microbi- vores, fungivores, predators, and omnivores (trophism unknown) were counted as such, but plant parasites were identified to species. Microbivores occurred in the highest numbers for all sampling dates, followed by plant parasites, fungivores, omnivores and predators. Fifty-eight plant parasitic species in 25 genera were identified, with one to sixteen species occurring in each site. Diversity was higher in March and Octo-than in July, higher in maple than in dogwood and peach blocks, and posi-tively correlated with percent weed ground cover and number of weed spe-cies in July. Paratylenchus projectus and Xiphinema americanum were the two most common species, occurring in 88% and 77% of the sites, respec-tively. A community ordination technique was employed to determine simi-larities among sites based on plant parasitic nematode communities

Soybean cyst nematode

"Soybean cyst nematode (SCN) is a plant nematode. Nematodes are microscopic roundworms, and plant nematodes feed on plant parts. Many different kinds of nematodes exist, and their common names often reflect their most important host."--First page.Terry L. Niblack (Department of Plant Pathology), and George S. Smith (Integrated Pest Management, College of Agriculture)Revised 2/90/10

Sampling for Plant-parasitic Nematodes in Corn Strip Trials Comparing Nematode Management Products

Protectant seed treatments are a new management option for plant-parasitic nematodes that feed on corn. Avicta from Syngenta Crop Protection became widely available for use on corn in the United States in the 2010 growing season, and Votivo from Bayer CropScience is now available for use on corn in the 2011 growing season. Many growers and agribusiness personnel working for co-ops, grain elevators, and seed and chemical companies are conducting strip-trial comparisons of nematode seed treatments in growers’ fields. Yield monitors in combines and/or weigh wagons can be used to collect yield data from multiplerow strips that stretch across an entire field. But some growers and agribusiness personnel also want to assess plant-parasitic nematode populations in these strip trials to gauge whether the seed treatments are affecting nematode numbers. Drawing conclusions about the effects of treatments on numbers of plantparasitic nematodes in strip trials is problematic because of the natural variability of nematode populations and their densities in the field. Plantparasitic nematodes are microscopic worms and their population densities can vary greatly over short distances. The variability in nematode population densities in two or more samples collected from the same treatment in a strip trial may be equal to or greater than the differences in nematode numbers in samples collected from two or more different treatments. And, if differences in numbers of nematodes from samples taken from different treatments are detected, one cannot assume that the differences are due to effects of the treatments. The inability to attribute differences in nematode numbers to treatment effects is especially true if only one sample is taken from each treatment. Multiple samples must be collected uniformly, consistently, carefully, and at the proper time in order to have a chance of detecting differences in nematode population densities among treatments

Phenotypic Characterization of a Major Quantitative Disease Resistance Locus for Partial Resistance to Phytophthora sojae

Major quantitative disease resistance loci (QDRLs) are rare in the Phytophthora sojae (Kaufmann and Gerdemann)–soybean [Glycine max (L). Merr.] pathosystem. A major QDRL on chromosome 18 (QDRL-18) was identified in PI 427105B and PI 427106. QDRL-18 represents a valuable resistance source for breeding programs. Thus, our objectives were to determine its isolate specificity and measure its effect on yield and resistance to both P. sojae and other soybean pathogens. We characterized near isogenic lines (NILs) developed from F7 recombinant inbred lines heterozygous at QDRL-18; NILs represent introgressions from PI 427105B, PI 427106, and susceptible ‘OX20- 8’. The introgressions from PI 427105B and PI 427106 increased resistance to P. sojae by 11 to 20% and 35 to 40%, respectively, based on laboratory and greenhouse assays, and increased yield by 13 to 29% under disease conditions. The resistant introgression from PI 427105B was also effective against seven P. sojae isolates with no isolate specificity detected. Based on quantitative polymerase chain reaction assays, NILs with the susceptible introgression had significantly higher relative levels of P. sojae colonization 48 h after inoculation. No pleiotropic effects for resistance to either soybean cyst nematode or Fusarium graminearum were detected. This information improves soybean breeders’ ability to make informed decisions regarding the deployment of QDRL-18 in their respective breeding programs

Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

Phenotypic Characterization of a Major Quantitative Disease Resistance Locus for Partial Resistance to Phytophthora sojae

Major quantitative disease resistance loci (QDRLs) are rare in the Phytophthora sojae (Kaufmann and Gerdemann)–soybean [Glycine max (L). Merr.] pathosystem. A major QDRL on chromosome 18 (QDRL-18) was identified in PI 427105B and PI 427106. QDRL-18 represents a valuable resistance source for breeding programs. Thus, our objectives were to determine its isolate specificity and measure its effect on yield and resistance to both P. sojae and other soybean pathogens. We characterized near isogenic lines (NILs) developed from F7 recombinant inbred lines heterozygous at QDRL-18; NILs represent introgressions from PI 427105B, PI 427106, and susceptible ‘OX20- 8’. The introgressions from PI 427105B and PI 427106 increased resistance to P. sojae by 11 to 20% and 35 to 40%, respectively, based on laboratory and greenhouse assays, and increased yield by 13 to 29% under disease conditions. The resistant introgression from PI 427105B was also effective against seven P. sojae isolates with no isolate specificity detected. Based on quantitative polymerase chain reaction assays, NILs with the susceptible introgression had significantly higher relative levels of P. sojae colonization 48 h after inoculation. No pleiotropic effects for resistance to either soybean cyst nematode or Fusarium graminearum were detected. This information improves soybean breeders’ ability to make informed decisions regarding the deployment of QDRL-18 in their respective breeding programs

Sampling for Plant-parasitic Nematodes in Corn Strip Trials Comparing Nematode Management Products

Protectant seed treatments are a new management option for plant-parasitic nematodes that feed on corn. Avicta from Syngenta Crop Protection became widely available for use on corn in the United States in the 2010 growing season, and Votivo from Bayer CropScience is now available for use on corn in the 2011 growing season. Many growers and agribusiness personnel working for co-ops, grain elevators, and seed and chemical companies are conducting strip-trial comparisons of nematode seed treatments in growers’ fields. Yield monitors in combines and/or weigh wagons can be used to collect yield data from multiplerow strips that stretch across an entire field. But some growers and agribusiness personnel also want to assess plant-parasitic nematode populations in these strip trials to gauge whether the seed treatments are affecting nematode numbers. Drawing conclusions about the effects of treatments on numbers of plantparasitic nematodes in strip trials is problematic because of the natural variability of nematode populations and their densities in the field. Plantparasitic nematodes are microscopic worms and their population densities can vary greatly over short distances. The variability in nematode population densities in two or more samples collected from the same treatment in a strip trial may be equal to or greater than the differences in nematode numbers in samples collected from two or more different treatments. And, if differences in numbers of nematodes from samples taken from different treatments are detected, one cannot assume that the differences are due to effects of the treatments. The inability to attribute differences in nematode numbers to treatment effects is especially true if only one sample is taken from each treatment. Multiple samples must be collected uniformly, consistently, carefully, and at the proper time in order to have a chance of detecting differences in nematode population densities among treatments.This article is published as Tylka, G. L., Todd, T. C., Niblack, T. L., MacGuidwin, A. E., and Jackson, T. 2011. Sampling for plant-parasitic nematodes in corn strip trials comparing nematode management products. Online. Plant Health Progress doi: 10.1094/PHP-2011-0901-01-DG. Posted with permission.</p