Quantitative PCR shows propagation of Plasmodiophora brassicae in Swedish long term field trials

Clubroot (Plasmodiophora brassicae) is a serious soil-borne disease in brassica crops world-wide. We report on a time series of soil samples from Swedish long-term fertility trials started in 1957, 1963 and 1966, which were analyzed for the amount ofP. brassicaeDNA. The crop rotations included a brassica crop every 4 or 6years. All experimental sites with a 4-year rotation of oilseed rape, except one with calcium carbonate in the soil profile, showed high (>1000fg DNA g−1soil) levels ofP. brassicaeDNA after 9, 11 and 12 rotations. In contrast, detectable levels (>5fg DNA g−1soil) ofP. brassicaewere found only at one of five sites with a 6-year rotation of spring oilseed rape. In years with high levels ofP. brassicaeDNA, low yield was reported and a subsequent decline inP. brassicaeDNA in soil was observed. Different NPK (nitrogen/phosphorus/potassium) fertiliser regimes resulted in similarP. brassicaeDNA levels. The robustness and reliability of the method applied was verified by analyses of soil from individual plots compared with a mixture of plots and by repeated analyses of selected samples, which showed thatP. brassicaeDNA remained stable during dry storage

Influence of seed treatment with mineral nutrient products on emergence and growth in spring oilseed rape (Brassica napus L.)

Seed treatment with mineral nutrients in spring oilseed rape (SOR) under cold climatic conditions has the potential to improve the outcome of production. The objectives of this study were to investigate the effects of mineral nutrients applied as seed treatment on germination and growth of roots and biomass in SOR. In addition, seed yield and oil content were also measured. Seed vigour tests and in-field experiments were performed in Central Sweden in 2016 and 2017. Seven products with different composition of mineral nutrients were applied to the seed in a combination with binder, filler and fungicide (BFF), or applied directly onto the seed. The results showed that a treatment with mineral nutrients increased the plant size at stage BBCH 60 (early flowering stage) when the products were applied in combination with BFF in the field experiments. However, the increased plant size did not influence seed yield. Furthermore, when seeds were treated only with a nutrient product the addition of BFF decreased plant size by 10% on average and seed and crude fat yields by 4% on average. The use of BFF may thereby be questioned and is subject to further investigation

Development of Loop-Mediated Isothermal Amplification Assay for Rapid Detection and Analysis of the Root-Knot Nematode Meloidogyne hapla in Soil

Soil analysis is crucial for estimating the risk of crop damage by the root-knot nematode Meloidogyne hapla. Here, we developed an analysis assay based on Loop-mediated Isothermal Amplification (LAMP). The LAMP primers were verified for specificity against 10 different nematode species. A manual soil DNA extraction, referred to as SKMM, was developed and compared with a FastDNA kit followed by DNA purification. DNA was extracted with both methods from artificially inoculated soils as well as from naturally infested soil collected from farm fields. The primers exclusively amplified DNA from M. hapla with both colorimetric and real-time LAMP. The detection limit was 193 gene copies and 0.0016 juveniles (12 pg mu L-1) per reaction. DNA concentrations and purity (A(260)/A(230)) were significantly higher using the SKMM procedure compared with the kit. From the field samples collected in 2019, DNA was amplified from 16% of samples extracted with SKMM and from 11% of samples using the kit. Occurrence of M. hapla DNA was confirmed in soil samples from two out of six field soils in 2020 using both real-time LAMP and qPCR. In conclusion, the developed real-time LAMP is a fast and specific assay for detection and quantification of M. hapla DNA in soil

Scientific evidence of sustainable plant disease protection strategies for oilseed rape (Brassica napus) in Sweden: a systematic map

BackgroundOilseed rape (OSR; Brassica napus L.) is a highly valued crop for food, feed and industrial use. It is primarily grown in temperate climates, and over recent decades, its area of production and profitability have increased. Concurrently, several diseases negatively impact OSR production. Diseases caused by soil-borne pathogens, pose a risk of substantial yield loss since crop rotation schemes have become narrow as the time lapse between OSR crops in a field has been shortened. The aims of this paper were to provide an overview of plant protection measures available for OSR production and to identify knowledge gaps and areas where more research is needed.MethodsThis systematic map builds on a previously published protocol and follows the ROSES reporting standard. The search strategy was developed in collaboration with stakeholders and designed to cover available scientific evidence for OSR disease management in climate zones relevant for Scandinavian crop production (Dfc, Dfb, Cfb and Cfa in the Köppen-Geiger climate classification). Five scientific databases were used to identify peer-reviewed literature, complemented by additional searches performed in grey literature. Articles were screened at three stages: the title, abstract and full text. The eligible publications included studies of OSR crops, and all measures to control crop disease in agricultural fields were considered eligible interventions. The comparator was intervention and no intervention, and the yield per unit area, disease suppression or an increase in crop quality were determined to be outcomes of interventions. A basic assessment of the experimental design of each study was performed to assess its eligibility. All articles were coded based on the following categories: the location and climate zone, disease, pathogen, intervention and management method, outcome and study design. Articles not reporting original data but judged to be relevant (i.e., review papers, books and notes of registration of cultivars) were saved in a separate category called “books, reviews and reports”.Review findingsA total of 4633 articles were collected through systematic searches. After duplicates were removed, 3513 articles were included in the screening process. After screening at the title and abstract levels, 897 articles were evaluated at the full text level, and 118 articles comprised the studies that met the eligibility criteria of the systematic map. The country (Canada) and region (Europe) with the largest OSR crop production areas also contributed the highest number of articles. In total, 17 different diseases were reported, with black leg (syn. Phoma stem canker) being the most studied disease. Nineteen different intervention methods or management types were examined. Cultivar resistance and pesticide application were the most studied control measures.ConclusionWe report scientific studies on plant disease protection measures for OSR based on field trials where the results are intended to be directly implemented in crop production management. The map clearly provides an overview of research progress throughout the time period chosen, and it identifies knowledge gaps regarding important diseases where only a few studies have been published, for example, diseases caused by viruses

Effects of sulphur fertilization in organically cultivated faba bean

Optimal seed yield and quality requires that the sulphur (S) demand of faba bean (Vicia faba L.) is ensured. The effect of S fertilization on organic cultivated faba bean was investigated under field conditions during two growing seasons (2017–2018), in Sweden. Kieserite (MgSO4) and gypsum (CaSO4) were applied at a rate of 20 and 40 kg ha-1 to study the effect on faba bean growth, yield, crude protein (CP) content and amino acid (AA) composition. Gypsum and kieserite significantly increased S concentration of faba bean dry matter (DM) in 2017. The S concentration ranged from 0.20% to 0.23% of DM compared to 0.18% in the untreated control. In 2018, kieserite application at 40 kg ha-1 significantly increased S concentration to 0.15% compared to 0.12% in the untreated control. The faba bean plants did, however, not respond neither with increased growth nor increased seed yield. The seed quality in terms of CP and S-containing AA, was not affected by S fertilization, however, significant differences were observed between the experimental sites

Rotröta påverkar uthålligheten hos vallbaljväxter

Rödklöver, som är basen i närproducerat protein, har sviktande uthållighet orsakad av rotröta som utvecklas i roten och orsakas av flera patogena svampar som finns i jorden. Angreppens påverkan på vallens botaniska sammansättning, produktionsnivå och kvalitet jämfördes i två fältförsök under tre vallår. Fröblandningar med olika baljväxter jämfördes i två- och treskördesystem. Baljväxterna som undersöktes var rödklöver SW Fanny (med och utan cikoria) och SW Vivi, vitklöver, käringtand och blålusern. Rödklöver gav störst totalavkastning över tre vallår. Baljväxthalten var högst i rödklöver de första två åren, trots stora angrepp av rotröta i vall II. Vallår III minskade rödklöverhalten signifikant och blev jämförbar med andelen vitklöver. Vivi skördad två gånger gav större avkastning än Fanny+ cikoria med tre skördar. I övrigt fanns inga signifikanta avkastningsskillnader mellan fröblandningar eller skördesystem i slutet av försöksperioden. Angreppen av rotröta var signifikant större i rödklöver än i övriga baljväxter. Blålusern hade större angrepp av rotröta än käringtand och vitklöver som låg på en låg nivå. Foderkostnaden blev minst med rödklöver respektive vitklöver i treskördesystem. Uthålligheten i baljväxtvallar totalt sett kan sannolikt ökas genom att alternera artvalet i baljväxtdominerade växtföljder med vitklöver, käringtand och blålusern som lämpliga alternativ till rödklöver