Industry representative: Seth Walpole
HDC project cost: £89,282
Crop damage previously associated with raspberry leaf and bud mite (RLBM), and now known to involve infection with a virus, Raspberry leaf blotch virus (RLBV) is an increasing problem around the UK. It affects particularly Glen Ample but increasingly other varieties. There is also a suggestion (preliminary results: J. Allen/S. MacFarlane) that the recent decline in certain varieties such as Tulameen and Octavia (poor lateral development, die back, blotchy leaves and malformed fruit) could be associated with this pest and/or virus. Stuart MacFarlane, virologist at the James Hutton Institute has proven the association between the mite and RLBV, however, increasingly, crop damage symptoms are being observed in the absence of the mite.
This project will carry out a UK-wide survey of plantations and do experiments to try and elucidate the links between the mites, the virus, plantation age, variety, yield loss and plant source in order to inform strategies for control.
• To determine how widespread RLBV is in UK floricane and primocane raspberry plantations;
• To confirm preliminary observations that RLBV is associated with plantation decline (failure of buds to break in situations where obvious symptoms of mite feeding or the virus are not displayed);
• To identify the cropping situations where RLBV occurs i.e. in propagation and/or in fruiting plantations) or where plants are being grown in close proximity to wild carriers (Rubus ideae);
• To identify whether RLBV infection is associated with mite numbers infesting plants and/or the levels of damage caused to infected plants by the mites feeding;
• To monitor how RLBV develops and spreads within a plantation;
• To monitor varietal susceptibility to mite and RLBV so as to identify any varietal traits which might be utilised by plant breeders to provide tolerance or resistance to the mite feeding and/or infection by the virus;
• Disseminate findings to HDC panel members through the project report and an article in HDC news or presentation at an event.
- Increased knowledge of the scale, severity and main causes of this disorder which is becoming an increasing problem for many commercially grown varieties, and one which increasing control of the mite does not appear to be controlling the symptoms;
- Potential to reduce crop damage through development of a rational control strategy based on this better understanding of the mite virus interaction;
- Knowledge of the problem gained in this project will be translated to the industry through annual reports, an article in HDC news and if appropriate presentations at grower meetings.