Tarragon Extracts (Artemisia dracunculus L.) in the Control of Selected Broad Bean Pests in Sustainable Pest Management

Legumes play an important role in agriculture by enriching soil with nitrogen, drawing water and nutrients from deeper soil layers, and supplying organic matter. They are also a valuable source of food for humans and animals. Protecting these plants from pests usually involves the use of synthetic products, whilst non-chemical methods remain poorly understood. The use of plant-based extracts is one possible approach. There is limited data in the available literature on the use of aqueous extracts (which is an easy and potentially low-cost solution) to protect legumes from pests. In particular, there is a lack of long-term studies conducted under field conditions. Accordingly, the aim of the three-year field studies was to determine the effect of aqueous tarragon extracts, prepared from dried and fresh plant material at concentrations conventionally defined as 2% (D2), 5% (D5) and 10% (D10) for the dried material, and 10% (F10), 20% (F20) and 30% (F30) for fresh material, on the control of two serious legume pests: Sitona spp. weevils and the broad bean weevil (Bruchus rufimanus Boh.). Aqueous extracts of tarragon reduced the area of losses and the percentage of leaf blade losses caused by adult Sitona spp. There were no significant differences between extracts using dry or fresh material as well as between different concentrations of the extracts. The effect of extracts was visible particularly during the early stages of plant growth in two out of three study seasons; this is especially significant given that these insects cause the worst damage during this period. No significant effect of the most studied extracts on the feeding of Sitona spp. larvae was observed. In D10 and F10 there was a significantly lower proportion of damaged nodules than in the control; however, this effect was markedly weaker than when Ch was used. All extracts from the dried plant material and F30 proved to be effective in reducing seed damage caused by B. rufimanus. However, the percentage of damaged seeds remained high, indicating that weekly application of tarragon extracts is not sufficient to protect broad beans against this pest. Taking into account the effect on the plants’ morphological parameters, the aqueous extract prepared from dried material at a concentration of 10% (D10) should be considered the most effective in practice. The damage caused by adult Sitona spp. and B. rufimanus differed significantly between years of the study.