Project Code: APMS/PRR22-030
Project Lead
Justin Renkema - Agriculture and Agri-Food Canada
Objective
To develop and facilitate adoption of integrated spider mite management systems that are based on viable and economically sound solutions
Spider mites, particularly the two-spotted spider mite (Tetranychus urticae), have been identified as a high priority pest impacting hop (Humulus lupulus) production in Canada. Spider mites have needle-like mouth parts that enable suction feeding on plant tissue which leads to collapsed leaf cells. Under heavy infestation, total leaf necrosis can occur which can result in yield loss. The most critical damage is caused to maturing hop cones in late summer resulting in direct economic loss through reduced cone quality due to brittleness. With females capable of laying over 100 eggs each, and with a week-long development cycle, spider mites have multiple generations within a season and populations build up rapidly in hot and dry conditions.
Currently, spider mite control primarily relies on multiple applications of a few conventional acaricide products, often applied as preventive treatments necessary to avoid economic damage. However, growers have limited viable options available to ensure sustainable mite control and curb development of pest resistance to acaricides. Thus, there is an increasing need for new knowledge, alternative solutions, and diversified systems approaches to help growers reduce the impact of spider mites on hops.
This project aims to study the optimal use of acaricides in combination with biological control tools as part of an integrated spider mite management system. Researchers intend to achieve this goal through advancing new and existing control solutions, such as: i) by characterizing the naturally occurring predatory mite communities in hopyards to elucidate their composition, diversity of species and abundance in relation to various crop management practices; and ii) by determining viable strategies combining applications of available acaricides and targeted releases of predatory mites (e.g. assessing rotation of various acaricides and use of economic thresholds for efficacy against spider mites, while evaluating compatibility and possible non-target effects on natural and introduced predators to ensure safe releases).
The knowledge gained from this study will be transferred to industry stakeholders and, if warranted, will facilitate adoption of a promising integrated management system which clearly demonstrates benefits for hop growers. It is anticipated that results generated from this project will lead to reduced reliance on acaricides for spider mite control and thereby, improve the sustainability of hop production in Canada.