Beauveria bassiana-based wettable powders can leave stains on plant leaves, fruits and vegetables. These stains are actually powder residue, which appears after the sprayed product has dried. This is a nuisance for greenhouse vegetable and fine herb growers, especially when they need to apply the product more than twice a week.
How are BioCeres WP residues created?
Some BioCeres WP ingredients are solid and poorly soluble. They are included to give the spores greater adherence and protect them from UV rays. Some ingredients can also prevent fungal diseases.
BioCeres WP is not the only product to leave residues. Its competitor does, too.
To better assess the effect of the residues, we compared BioCeres WP with its competitor on the Canadian market, also a wettable powder. We applied the recommended doses of both products (4 g/L for BioCeres and 2.5 g/L for the competing product) on tomatoes and peppers twice in one week. We conducted the tests twice, on 12 tomatoes and 12 peppers (24 total replicas of each fruit).
The results showed that BioCeres WP at 4 g/L and the competing product at 2.5 g/L left similar deposits. The residue problem is therefore not unique to BioCeres WP, but an issue with all wettable powders.
Finding a solution for growers
Anatis Bioprotection’s Bioinsecticide division team, along with Martin Nadeau, Ph.D, scientific director and research professional, and Jorge Fernandez, M.Sc., decided to try finding a wetting agent that would reduce residues.
After talking with several MAPAQ agronomists and agricultural advisors from the Réseau d’avertissements phytosanitaires, we selected and tested two products: Activ 0-0-5 (a liquid seaweed concentrate accepted in organic production) and EPSO Top (magnesium sulphate) used in conventional production. The two products are compatible with BioCeres WP and do not negatively affect the Beauveria bassiana spores.
|Products||Concentration (%) *||Presence of residue|
|Epso Top||5,0 **||No|
* These concentrations are the ones recommended by the product manufacturer.
** Source : EpsoTop
Conclusion : BioCeres WP residues can be easily controlled.
Adding EPSO Top (5% concentration) to BioCeres WP eliminates the presence of residues on the surfaces of fruits in conventional production.
For organic production, we will be continuing our research to find a wetting agent that is accepted and effective. The search continues!