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Grafting tomato (Solanum lycopersicum L.) onto disease resistant rootstocks has grown in use in North America over the past two decades. Rootstocks have traditionally been bred and used for their resistance packages to numerous soil-borne diseases but some rootstocks appear to improve scion yield and vigour in comparison to non-grafted plants in conditions lacking disease challenge. In this study, the tomato rootstocks 'Maxifort' or 'RST-106' were used to determine if vigour improved 'Tribute' scion traits, especially yield, and if marketable yield could be maintained in grafted plants at reduced nitrogen fertiliser inputs. Plants were grown in an open-field plasticulture production system at five rates of nitrogen from 0 kg ha−1 to 224 kg ha−1 applied via drip irrigation. Marketable yield was significantly affected by nitrogen rate and rootstock in both years. 'Tribute' grafted onto 'Maxifort' rootstock had the greatest, most consistent impact and increased marketable yield 15% and 30% in 2013 and 2014, respectively, compared to the non-grafted 'Tribute'. Our findings suggest that some rootstocks can increase scion growth and yield but do not differentially respond to decreased nitrogen rates. [ABSTRACT FROM AUTHOR]

A rotation trial spanning nine consecutive growing seasons was established in 2004 to study cumulative effects of specific onion- and potato-focused crop rotations on soil nutrient levels, soil biological communities, plant productivity and soilborne diseases. Soil microbial activity, as determined by fluorescein diacetate hydrolysis, was greatest in the ‘sustainable’ potato rotation in five of the 6 years that the test was carried out.Rhizoctonia solanianastomosis group 3 DNA was first detected in potato monoculture soils in the fifth year, with numbers increasing from then on, but was not detected in the onion monoculture throughout the trial period. Potato yields were greater when a crop other than potato was grown in the previous year compared with when potatoes were the preceding crop. After 2005, mean annual onion yields from the onion monoculture were less than yields from the other rotations. Black scurf on potato tubers was the primary soilborne disease observed during the study, and the incidence of this disease was greater in the potato monoculture than the other rotations after the second year, and least when potatoes had not been grown in the same ground the three previous seasons. This long-term crop rotation study has demonstrated the benefits of a ‘sustainable’ rotation where potatoes or onions were grown every fourth growing season, with different crops (oat, broccoli, cabbage, squash) grown in the intervening years, compared with the conventional consecutive biennial crops of potato and onion. [ABSTRACT FROM PUBLISHER]

PSX is a combination of biocontrol bacteria that can potentially prevent and control soil-borne diseases for a variety of crop cultivars. In this study, we investigated the utility of PSX in controlling root-knot nematodes in tomato under field conditions. The application of PSX reduced the severity of disease caused fromMeloidogyne incognitaby 63–69% and increased tomato yield by 31.5–39%. Furthermore, to investigate the effect of PSX treatment on tomato fruit quality, we quantified the soluble sugar, titratable acid, soluble solids, and vitamin C contents in fruit postharvest. We demonstrated that PSX treatment improved tomato fruit quality. Finally, we also showed that the total nitrogen (N), available N, potassium, and organic matter contents in the soil increased after PSX treatment. PSX is a promising biocontrol preparation that can provide beneficial effects to tomato growers, including biological control of root-knot disease, plant growth promotion, enhanced tomato fruit quality, and increased levels of organic fertilisers in the soil. [ABSTRACT FROM PUBLISHER]

Oomycetes are eukaryotic microorganisms morphologically similar to but phylogenetically distant from true fungi. Most species in the genusPhytophthoraof oomycetes are devastating plant pathogens, causing damages to both agricultural production and natural ecosystems. Tremendous progress has been achieved in recent years in diversity, evolution and lifestyles of oomycete plant pathogens, as well as on the understanding of genetic and molecular basis of oomycete–plant interactions.Phytophthora parasiticais a soilborne pathogen with a wide range of host plants and represents most species in the genusPhytophthora. In this review, we present some recent progress ofP. parasiticaresearch by highlighting important features that make it emerge as a model species of oomycete pathogens. The emerged model pathogen will facilitate improved understanding of oomycete biology and pathology that are crucial to the development of novel disease-control strategies and improved disease-control measures. [ABSTRACT FROM AUTHOR]

In this research, the activity of antagonistic activity of 200 soil-borne Streptomycetes isolates assayed againstPhytophthora parasiticaandP. citrophthorain Kerman Province was investigated. Primary screening for antimicrobial activity was determined by dual culture experiments and 20 isolates showed high level of fungicidal activity in Agar disc method. The soils of Kerman are rich sources of microorganisms with potent biological activities and screening programmes are to be conducted to reveal the presence of active Streptomycetes isolates. [ABSTRACT FROM AUTHOR]

In this study, biological activity of 70 ofStreptomycessp. isolates was evaluated against black rot stem of greenhouse cucumber in dual culture techniques. Among all isolates which were screened, isolates O-15 showed high level of activity in agar disk and well diffusion methods againstPhoma glomerata. In the shacked cultures,Streptomycessp. isolate O-15 activity reached maximum after 18 days, againstPhoma glomerata. This isolate did not have high salt tolerance in nature. [ABSTRACT FROM PUBLISHER]

Lysobacter capsiciYS1215 is a soil-borne strain that could inhibit the growth of phytopathogenic fungi, includingPhytophthora capsici, Rhizoctonia solaniandFusarium oxysporum, as well as root-knot nematodes. The effect of different concentrations of bacterial culture filtrate (BCF) ofL. capsiciYS1215 on the mortality of second-stage juveniles (J2) ofMeloidogyne incognitawas studied using 24-well plates. The J2 mortality increased with increasing concentrations of BCF. YS1215 also produces gelatinases in the culture filtrate. To study its role in nematicidal activities, the partial purification and the characterisation of gelatinolytic proteins were done from the culture medium of the YS1215. The partially purified proteins showed three clear bands with molecular weights estimated using zymography to be 255.7, 232.1 and 146.4 kDa. The optimal pH and temperature for the proteins were 8.0 and 40°C, respectively. The activity of the proteins was inhibited by ethylenediaminetetraacetic acid, FeCl3and 1,10-phenanthroline, whereas it was activated by MnCl2. The proteins may belong to the group of metalloproteases. Moreover, the proteins could hydrolyse skimmed milk, collagen, gelatin and bovine serum albumin (BSA) as substrates, but not casein. The proteins could induce 75% J2 mortality in five days and degrade the J2 bodies. The present study demonstrates the role of the gelatinolytic proteins in the nematicidal potential ofL. capsiciYS1215. [ABSTRACT FROM AUTHOR]

Aspergillus niger, a soil-borne fungus is a causative agent of hypocotyl malformations in infected groundnut (Arachis hypogaeaL.) plants, but its effect on yield is unknown. This study sought to determine its effect on growth and yield. Seeds of Chinese and JL45 varieties were sown in soil inoculated withA. niger. Fresh and dry weights of the shoots and roots were taken at 10-day intervals. Nodule count was done at 30 days after emergence and subsequently at 10-day intervals. Pods of 20 plants each from inoculated and uninoculated soils were harvested. Growth was suppressed in plants grown onA. nigerinoculated soil. Eight-day old plants grown in inoculated soil developed curvatures on their hypocotyls. Nodulation was suppressed (p < 0.05) in plants grown in inoculated soil. Although growth was suppressed in plants grown on inoculated soil, yield of both varieties of groundnut was not affected. [ABSTRACT FROM AUTHOR]

The article evaluates the potential for systemic infection of barley and wheat heads from soil- and seed-borne sources of inoculum, Fusarium graminearum and Fusarium pseudograminearum, in Alberta. The inoculants that are isolated from corn grain and cereal node tissue were used to study the infection from soilborne sources of inoculum. Four methods were used for the inoculation of healthy seeds to induce infection. Results show that no evidence was found for systemic infection from seed.

The article cites a study about the efficacy of fish emulsion as a preplanting soil amendment for controlling the prevalence of soilborne diseases on eggplants and potatoes. The researchers conducted a test on 11 samples of soils from different commercial potato fields in Canada with a history of verticillium and scab. Results of the study concluded that treatment of fish emulsion significantly reduced the prevalence of the said plant diseases, though not on soils with high disease pressure.

Soil microorganisms drive nutrients cycling to a great extent, and they play an essential role in maintaining a stable soil ecosystem and ensuring sustainable forestry development. Land management has been proven to be a real factor in influencing soil quality. The purpose of this study was to investigate the effects of different land management techniques on soil microbial communities. There were four types of land management systems selected for this study: natural masson pine, Phyllostachy pubescens, Phyllostachys praecox, and vegetable. Soils were sampled from these four systems and assayed for soil microbial biomass carbon (MBC), community level substrate utilization pattern, functional diversity, and principle component analysis. Values of MBC were significantly different (P<0.05) from one another in the order of masson pine>Phyllostachy pubescens>Phyllostachys Praecox>vegetable. Analysis of community level substrate utilization pattern indicated that carbon source utilization and total activity by soil microorganisms were greater under the masson pine system than the other three systems (P<0.01). The functional diversities of soil microbial communities characterized as Shannon and McIntosh indexes were much richer in soil under masson pine system; Shannon index was 4.483, 4.241, 4.224, and 3.938 and McIntosh index was 13.51, 7.332, 6.272, and 6.261 for natural masson pine, Phyllostachy pubescens. Phyllostachys praecox, and vegetable systems, respectively. The results from the principle components analysis (PCA), based on the data of optical density (OD) at 120 h of incubation, showed that the value of the first principal component (PC1) of soil for natural masson pine was greater (P<0.05) than those for the other three systems. The difference in scores of the second principal component (PC2) between Phyllostachy pubescens, Phyllostachys praecox, and vegetable were not statistically different. The size and activity of soil microbial communities generally decreased with soil depth, with significant differences in soil MBC, community level substrate utilization pattern, and functional diversity indexes found between A and C horizons (P<0.01). It was concluded that land management systems had a great influence on soil microbial biomass, activity, and functional diversity. [ABSTRACT FROM AUTHOR]