Evaluation of alternative pesticides and pest repellent plant and other extracts for vine pest management, particularly for use by small scale farmers
An extensive literature survey showed that a great variety of botanical and other natural products have been documented as repellents or pesticides for crop pests. Botanical pesticides are not without risks, as some are toxic to humans and other mammals, some cause intense skin irritation or are carcinogenic, and some leave harmful residues. Under conditions of low ant pressure, extracts of crushed ants, syringa and tomato plants showed limited repellent effects against pugnacious and Argentine ants, ranging from 39 to 93 days. When ant pressure was high, crushed ant and crushed garlic extract repelled both types of ant for just more than a week only. Best results were achieved with extracts of crushed ants. This product could be used by small scale producers to keep ants out of vines, but will need to be applied at regular intervals during the season.
Latex extracted from melkbos (Euphorbia sp.) was diluted with water and tested as a repellent stem barrier against Argentine ants in a vineyard. While the solution was still wet, ants were noticeably repelled. As soon as the mixture began to dry, however, ants were seen crossing the treatment band.
The advent of the Scheme for Integrated Production of Wine (IPW) which requires producers to use registered pesticides only, the lack of quality control and consumer safety guarantees when using home-made botanical extracts and the fact that many agrochemical companies are now marketing smaller quantities of their products mean that home-made botanical extracts are no longer feasible options for small scale commercial wine grape producers. It is recommended that this project be terminated. Future research should focus on affordable application techniques and apparatus for registered pesticides that can be used by resource-limited commercial farmers. A need for technology transfer and training of emerging farmers regarding integrated pest management and the principles of IPW was identified.