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Reducing residues on the surface of fruits and vegetables when applying BioCeres WP (Beauveria bassiana)

Published on: | Created by: Roxanne S. Bernard

Tags: beauveria bassiana, bioceres

Residues of Beauveria Bassiana (BioCeres WP) on tomato surface
Martin Nadeau
Martin Nadeau

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).

Beauveria Bassiana residues on tomatoes
Fig.1 Tomatoes and peppers tested in Anatis Bioprotection’s laboratory

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.

Beauveria Bassiana residues on tomatoes
Visible residues (whitish stains) on a tomato after applying A) BioCeres WP at 4 g/L and B) competing product at 2.5 g/L.

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.

The results

Products Concentration (%) * Presence of residue
Control n/a Yes
Activ 0-0-5 1,5 Yes
1,0 Yes
0,1 Yes
Epso Top 5,0 ** No
4,0 No
3,0 No
2,0 No
1,0 Yes
0,01 Yes

* These concentrations are the ones recommended by the product manufacturer.
** Source : EpsoTop

Beauveria Bassiana residues on tomatoes
Fig 3. A) Visible residue (reddish stains) on a tomato after applying 4 g/L of BioCeres diluted in Activ 0-0-5 at 1.5% B) Lack of residue on the tomato after applying 4 g/L of BioCeres diluted in EPSO Top 5%.

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!

See the BioCeres WP product sheet

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