Clubroot Control for Cruciferous Crops

Measuring the efficiency of developed organic fertilizers and biological plant protection formulas to reduce problems caused by pathogenic organisms.

The aim of the activity is to evaluate the effect of biological preparations on the control, plant health and yield of common canola pathogen Plasmodiophora brassicae. Biological preparations contain a variety of microorganisms, the actual effectiveness of which in controlling pests depends significantly on the local microorganism community, the susceptibility of the host plants, and environmental conditions such as temperature, humidity, total sunlight. The aim is to find suitable biological preparations for  local weather conditions.

We test the following biological preparations for the control of the soil pathogen Plasmodiophora brassica:

  • Mycostop ( Streptomyces griseoviridis K 61), Danstar Ferment AG
  • Prestop ( Gliocladium catenulatum J 1446), Danstar Ferment AG
  • Serenade ASO ( Bacillus subtilis QST 713), Bayer AG
  • Trifender Pro ( Trichoderma asperellum T34), Kwizda Agro

Laboratory tests are carried out in a controlled environment on a crop variation susceptible to the disease. Samples of infected soil are collected and assessed. The effect of the preparations on the occurrence of damage, suppression of the disease and reduction of the pathogen in the soil is studied. To this end, disease severity index (DSI) and pathogen abundance are determined using molecular methods. The effects of potential biological preparations on soil conditions, suppression of the disease are also being investigated; the level of reduction of the pathogen in the soil is evaluated.

We provide recommendations on how to select organic rapeseed growing areas with a lower risk of infection, reducing risk of crop loss and help farmers choose crop varieties that are more resistant to the pathotype. 

Activities
  1. Suitable methods for collecting test material and performing laboratory tests were identified, and preparations registered in Estonia containing at least one biologically active microorganism with potential for biocontrol were selected.
  2. Due to the lack of preliminary information about the spread of the plant pathogen, field monitoring was performed and soil samples were collected from summer swede rape fields based on visual detection.
  3. In addition, soil samples were collected from fields of different crops (barley, wheat, clover, hay) where, according to the information of farmers, there was a previous infection, and the next crop in rotation was rape, accordingly. In total, samples were collected from 30 fields located all over Estonia: Viljandi County, Tartu County, Lääne-Viru County, Jõgeva County, Valga County, Tartu County and Ida-Viru County.
  4. An experimental design was developed and the first field trials were performed under controlled conditions to evaluate the effect of biopreparations on the occurrence of Plasmodiophora brassicae damage, disease suppression and pathogen reduction in soil. For this purpose, four different biofungicides were tested. Soil from two particularly highly infectious fields as well as infectious material were used for the experimentsLaboratory tests were performed on natural infection and sterilized field soil inoculated with a solution containing P. brassicae spores. 
  5. Based on the molecular and physico-chemical analyzes of the soil samples, a methodology was developed for a follow-up experiment, which uses not only a better-performing biopreparation but also a developed prototype of fertilizers.
Results

The experiments showed that no statistically significant difference was found between the different treatments. However, there was a tendency for soil samples treated with Prestop and Mycostop  to have lower P. brassicae concentrations compared to the control. A similar trend was observed for both non-sterile and artificially pathogen-infected soils. 

The tests revealed that the concentration of the biological preparation added to soil plays  an important role in reducing the pathogen. To the best of our knowledge, some preparations appear to have low standard recommended by the manufacturer. In view of the preliminary results, a follow-up experiment was started. 

The photo shows a test experiment with biopreparations at the Estonian University of Life Sciences.

Partner:
Estonian University of Life Sciences – Kaire Loit, Britt Puidet
Estonian Crop Research Insitute – Riinu Kiiker