On-farm field demonstration of the use biofungicides within an integrated approach to manage Sclerotinia diseases in dry bean and canola crops

Project Code BPI08-030

Project Lead

Ty Faechner - Agricultural Research and Extension Council of Alberta

Objective

This project aims to demonstrate in a commercial setting that recently registered biofungicides can be effectively incorporated into integrated pest management systems, are economically viable and can be effectively communicated to farmers

Summary of Results

Background

Diseases caused by the soil-borne fungus Sclerotinia sclerotiorum are an economic threat to many important crops worldwide, including canola and dry bean. Managing Sclerotinia diseases of canola and dry bean (also known as white mold) in western Canada has been a challenge because the fungus can survive in soil for many years as hardened sclerotia. If disease is not properly controlled, the sclerotia population builds up every time a susceptible host crop is grown in a field. Application of foliar fungicides has been the main control method; however soil treatment options were necessary for improved management.

Two new biopesticides, Contans WG (through the Pesticide Rist Reduction Program's biopesticides regulatory support program) and Serenade Max were registered for use in Canada to control white mold diseases in several vegetable and field crops, including canola and dry bean. Based on a naturally occurring fungus, Coniothyrium minitans, Contans can attack and destroy sclerotia in soil before these germinate and release ascospores to infect susceptible plants. It can be used either as a pre-sowing, soil-incorporated treatment in advance of growing a crop susceptible to S. sclerotiorum or as a treatment of plant residues following the harvest of a susceptible crop. The Conithyrium fungus requires time to establish in the soil and will then act as a field sanitizer by suppressing sclerotia build up over time. Serenade Max, based on Bacillus subtilis (strain QST 713) can be used as a spray application to manage foliar disease. Both of these products can be part of integrated pest management (IPM) systems along with existing tools, and potentially complement the effect, and/or minimize the use of fungicides. However, there was limited grower knowledge about the mode of action of these products and their proper use in existing crop production systems. 

The goal of this 3-year on-farm demonstration project was to increase awareness of new reduced risk biofungicide tools, to fine-tune and promote the adoption of integrated approaches for white mold control, and to help growers become familiar and gain hands-on experience with the use of these novel biofungicides. Developed in collaboration with the Canola Council of Canada, Pulse Canada, and respective biopesticide companies, this project supports the implementation of the Reduced Risk White Mold Strategy.

Approaches

The project was conducted from 2008 to 2010 on multiple commercial canola and dry bean farms in the irrigated region of southern Alberta. To ensure compatibility with ongoing operations, strips of commercial fields were treated with the biofungicides in addition to what a grower would normally do to manage his crop. Because this project was done under commercial conditions, there were few untreated control areas.

Project fields were followed for 3 seasons to allow sufficient time for Coniothyrium minitans, which helps reduce pest inoculum in the medium to long term, to do its job. In addition to the on-farm project plots, demonstration plots were also set up at the “Farming Smarter” research and development site near Lethbridge.

Overall, 28 Contans treatments were made on 9 field sites and at the demo site with various application rates, timings, methods of incorporation in soil, and sequences of susceptible and non-susceptible crops. Tested rates included 2 and/or 4 kg/hectare Contans applied in the fall and/or spring, following or preceding canola, dry bean, or non-susceptible crops. The product was incorporated into the soil using tillage, precipitation or irrigation, and was applied alone or combined with various foliar fungicides [Lance (boscalid), or Allegro (fluazinam)] applications. Serenade Max was tested in 12 fields annually, six of which were also treated with Contans. Treatments consisted of foliar applications at 3 to 5 L/hectare Serenade Max at timing similar to other fungicide applications. Treatments included Serenade Max alone and tank-mixed with Lance or Allegro. Crop samples in all treatments were rated for disease incidence and severity, and yield was assessed at harvest. 

Results and Conclusions

Over the course of three years, growers and extension specialists worked closely with biofungicide registrants and distributors to gain hands on experience with the use of these novel products in a commercial setting. Project approaches and results were extensively communicated to growers through field days, crop walks and numerous publications in local grower media.

Overall, the highest levels of disease incidence (70-100%) across all trial sites, except one, were recorded in 2009. In 2010, disease incidence was below 50% in most sites, with only one site reaching levels above 90%. Extreme weather conditions ranging from drought to excess moisture and flooding posed some challenges during this project, and in some cases interfered with treatment applications and influenced disease pressure.

Positive results were observed for both biofungicide treatments at a number of project sites, though results were not always conclusive, in part due to the fact that the commercial nature of the project sites did not always allow for untreated checks. Yield increases, however, were observed at varying degrees in almost all cases where the treatment with these biofungicides was compared with an untreated check. For instance, in some cases, a combination of Contans (particularly at the higher rate) with Lance resulted in superior yield advantages. Clearer differences were observed in 2009, when disease pressure was at highest levels due to weather that favoured disease development.

Both biofungicide products faced a significant test, as disease pressure is usually high in southern Alberta due to the use of irrigation, the endemic nature of Sclerotinia sclerotiorum, and the intensive rotation of susceptible crops. The biofungicides performed well despite these challenging conditons. Currently, the greatest barrier to more widespread adoption of these biofungicides appears to be the perceived return on investment, as not all growers are convinced that the extra cost for biofungicides is justified by the increase in yield. This is perhaps confounded in part by the longer‐term benefit anticipated, specifically with Contans where the full impact may not be realized until a few years following the application (i.e. preventive vs. curative approach to crop protection). This can make it difficult to assess and compare against conventional products, where the efficacy and yield benefits are linked directly to the crop receiving the application.

In conclusion, this project has significantly raised awareness of the role of reduced risk biofungicides in the management of white mould in pulse crops and canola, thereby contributing to pesticide risk reduction in these crops. In addition, this work has acted as a catalyst for ongoing extension research to enhance IPM systems which integrate such products, and has brought registrants, growers and extension specialists together to work on improving application techniques and timing and adding new label instructions.

For more details on this project, please contact Ken Coles of Farming Smarter.

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