New biological control strategy for rot control in grapes

Researchers from IRTA and the Polytechnic University of Valencia (UPV) have developed a new water-dispersible granule biocontrol formulation for grape cultivation. The granules are dissolved in water and sprinkled over the plants; an eatable innocuous film forms on the crop surface, protecting the plant from the rot caused by Botrytis cinerea, one of the primary causes of deterioration and loss for the wine sector. Part of this study has been recently published in Biological Control and has received funding from the National Institute for Agricultural Research (INIA) and the European Regional Development Fund (FEDER).

The yeast Candida sake CPA-1 is the main ingredient of the new formulation. This biocontrol agent was isolated and developed by IRTA and the University of Lleida (Catalonia); its effectiveness in the control of the primary post-harvesting diseases in stone fruit crops had been previously shown, being a very interesting alternative against chemical fungicides. The coordinated studies between researchers from the UPV (experts in coating) and IRTA (experts in biocontrol and microorganism production/formulation), have allowed developing novel formulations with this microorganism ensuring its highest effectiveness, lastingness, and resistance once applied on the plants. Amongst the products used for obtaining the dispersions for the coating, the most efficient are pregelatinized potato starch and sodium caseinate.

Amparo Chiralt, researcher of the Institute of Food Engineering for Development at the UPV, pointed out: “Once applied over the crops, a film is formed allowing the microorganism to attach to the plants making it more resistant to rain or other adverse environmental impacts”. Furthermore, Neus Teixidó, the person in charge of this study at IRTA, said: “By surviving better in field conditions, increased effectiveness of the biocontrol agent is expected and consequently a more efficient control of the disease, reduced rot and lower losses”.

Proven effectiveness

Last summer, IRTA performed the first field tests of the new product in the commercial exploitation of the “Costers del Segre” Designation of Origin and obtained highly encouraging results. The researchers will apply the product again this year to confirm the results and analyse the incidence of possible variations of meteorological conditions.

Regarding its use, the guidelines and phases of conventional treatments with insecticides against Botrytis cinerea will be followed in the fields.

The collaboration between the UPV and IRTA has allowed for the first time the development of a biocontrol agent with substances capable of forming a film or coating on the surface of the plants that need protection. For creating this solid formulation, a novel technology was used combining the atomization of yeast cells and the appropriate additives for its formulation and fluidized bed drying. This technology is available in IRTA´s Fruitcentre (Lleida) Microbial Production and Formulation pilot plant.

The relative humidity levels and temperature at which the product has to be kept to ensure maximum effectiveness and shelf life were also determined. According to Ana Marín, researcher of the Institute of Food Engineering for Development at the UPV: “Ideally, it is better to keep the product refrigerated under the lowest possible levels of humidity. When the farmer decides to use it, the only thing he/she has to do is to take it out from the container and dissolve it in water. Once the mix is ready, Candida sake cells revitalize and the formulation is ready to be applied to the crops”.

Other joint lines of work

The UPV work team and IRTA are also studying biological control agents packed in microcapsules and their use on cucurbitaceous crops, as well as novel encapsulated non-toxic natural products, as for example the components of essential oils for plague control in the fields.

Reference

A. Marín, M. Cháfer, L. Atarés, A. Chiralt, R. Torres, J. Usall, N. Teixidó. 2016. Effect of different coating-forming agents on the efficacy of the biocontrol agent Candida sake CPA-1 for control of Botrytis cinerea on grapes. Biological Control, 96: 108-119.