Evaluation of CLO1 for management of grey mold on greenhouse tomato

Project Code BPR11-020

Project Lead

Gary Coukell  Integrated Crop Management Service (ICMS)


To develop efficacy and crop tolerance data in support of a regulatory submission of CLO1 (Clonostachys rosea) for the control of grey mould (Botrytis cinerea) in greenhouse-grown tomato

Summary of Results


Grey mould caused by Botrytis cinerea is an important disease in greenhouse-grown tomatoes (Lycopersicon esculentum). The pathogen causes serious grey mould symptoms on stems, leaves, flowers and fruits, and thus yield losses. Fungicides, applied as sprays or as pastes to stems, continue to be important for control. However, a general goal in crop protection for greenhouse vegetables is to reduce chemical fungicide inputs. The use of biopesticides would be a desirable alternative to suppress B. cinerea in commercial greenhouse tomatoes in Canada. Grey mould in greenhouse tomato was selected as a priority issue by growers at the annual Biopesticides Priority Setting Workshop in 2010, and Clonostachys rosea ACM941, developed by Agriculture and Agri-Food Canada, was selected as the priority solution for this disease.

C. rosea CLO1 has demonstrated significant effectiveness for suppressing B. cinerea in greenhouse-grown tomatoes in Canada. Studies of the mode of action demonstrated the ACM941 strain suppressed B. cinerea by the competition for nutrients and parasitizing hyphae, spores, and sclerotia of B. cinerea. This project was undertaken to test efficacy of ACM941 for the control of grey mould in greenhouse tomato, identify the application rates, and test the tolerance of tomato plants to this biopesticide.


The rate screening and efficacy trials were conducted on transplanted greenhouse tomatoes at Abbotsford, British Columbia in 2011 and 2012. One hive of bumble bees was placed in the middle of the research greenhouse to help pollination and also for assessment of any negative affects by the product.

The screening trial consisted of 4 application rates (0.025 grams per litre (g/L), 0.25g/L, 2.5g/L and 12.5g/L) of ACM941 in 2011. Two application rates (2.5g/L and 12.5g/L) were selected for the efficacy trials in 2012. All trials included Decree (0.75 kilograms per hectare (kg/ha)) as a commercial standard. The trial plants were inoculated with grey mold (B. cinerea) before the first application. Six applications were made for each of the ACM941 treatments at a weekly interval.

Disease plant incidence and severity on leaves, stems, flowers and fruits were assessed at a weekly interval until harvest. Marketable and unmarketable yields from each plot was assessed and expressed in kilograms per meter squared (kg/m2). Crop tolerance was assessed at the same time as disease incidence and severity, using a 0 to 100% visual rating scale to evaluate phytotoxicity.


Two trials were conducted in the greenhouse in 2011 to establish the appropriate product rate for management of Botrytis grey mould on greenhouse tomato. Disease pressure developed slowly on all plant parts after the inoculation and treatments in both trials did not show significant difference from the untreated until 34 days after application in Trial 1 and 21 days after application in Trial 2.

Of the four rates tested, the treatments at 2.5g/L and 12.5g/L were significantly better than others, both reducing disease incidence by over 96% and disease severity by approximately 89% on leaves at 43 days after the first application in two screening trials. At the end of the trials at day 82 after the first application, these two treatments continued to show good efficacy related to disease symptoms on leaves. The results of these two trials showed that at the two rates noted, the product provided better efficacy than the commercial standard treatment (Decree at 0.75 kg/ha). In addition, efficacy was observed on flowers, stem and fruit, although not at as high a level as on leaves.

Two efficacy evaluation trials were conducted in 2012 using the best application rates, 2.5g/L and 12.5g/L, identified in 2011. Despite inoculation with the disease pathogen in the greenhouses, disease pressure was too low for efficacy evaluation during the trials. Significant efficacy was observed on leaves only at day 66 after the first application. The two rates reduced severity by 35% and 32%, respectively, and incidences by 43% and 68%, respectively, on leaves. Other treatments did not show any difference compared with untreated in efficacy trials.

Yields were evaluated in all trials conducted over the two years, but no differences were observed among treatments.

Over the course of the two years of trials, no crop phytotoxicity was observed, and no negative effects of the biopesticide on bees were observed.


Four trials were conducted for evaluation of ACM941 for the control of Botrytis grey mould in greenhouse tomato. Generally these trials showed that ACM941 (C. rosea) significantly reduced disease incidence and severity of Botrytis grey mould on leaves and flowers and provided comparable or better efficacy than the commercial control Decree. These trial data can be used to support a regulatory submission of the biopesticide for the control of grey mould (B. cinerea) in greenhouse-grown tomato.

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