Inhibitory effect of cheese whey on cucumber mosaic virus and pepper mottle virus in capsicum annuum

Evaluations were made for the effects of cheese whey treatment on infection of pepper plants by cucumber mosaic virus-Vch (CMV-Vch) and pepper mottle virus-Kr (PepMoV-Kr). In a greenhouse, pepper plants sprayed with whey, prior to inoculation by CMV-Vch using aphids, showed a viral infection rate significantly lower (6.6%) than for the control (23.3%). In an open field experiment, in which CMV infection relied on natural transmission by aphids, pepper plants were sprayed with undiluted whey once a week, starting on the transplanting date (May 2) to the end of June. On June 5, these whey-sprayed plants showed a CMV infection rate reduced by 18.9% and 16.7%, compared to untreated and pesticide-treated plants, respectively. In the greenhouse, pepper plants inoculated with PepMoV-Kr mixed with whey showed a viral infection rate decreased by 60% compared to the control. The accumulated amount of PepMoV-Kr coat protein was less than that for the virus-only control at 6 days post inoculation (dpi), but increased up to a similar level as the control at 9 dpi. This study showed that cheese whey is effective in reducing infection of both CMV and PepMoV in pepper plants.