Description
The plant disease downy mildew threatens the organic production of numerous food plants, such as grapevine, hops and some fruits and vegetables. Today the only available fungicides in organic farming are based in copper. However, due to its accumulation in soils and negative effects on birds, small mammals and earthworms, the European Union demands a reduction of the heavy metal and even considers a ban, if an environmentally friendly alternative is found. Therefore, a new substance must be discovered or else the organic production of mentioned foods is in jeopardy. During the investigation of possible alternatives, an extract from hop cones was reported to have a fungicidal effect against downy mildew. However, to use the highly viscous, poorly water soluble and unstable extract as a plant protecting agent, its product properties need to be adapted to the application.
The formulation method of microencapsulation was used in this research project in order to transform the hop extract into an applicable and highly active powder, which should provide a long-lasting effect. Using the spray congealing process, the active ingredients were encapsulated into a solid lipid matrix particle. Adjuvants, such as emulsifiers, dispersing agents and antioxidants, were included into the capsule to optimize the product features for its use in plant protection. Finally, leaf-disc-assays showed, that the developed capsule-prototypes can prevent an infection with the pathogen completely. Thereby it could be proven that microencapsulated hop extract is a promising plant protecting agent against downy mildew that might be able to replace copper in the future.
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