The potential of reflective mulching in combination with insecticide sprays for control of aphid-borne viruses of iris and tulip in Tasmania

Silver coloured plastic mulches and weekly insecticide sprays were examined individually and in combination for efficacy in reducing spread of tulip breaking potyvirus (TBV) in tulip, and these plus mineral oil treatments, alone and in combination with insecticide and mulch, were evaluated for their effect on iris mild mosaic potyvirus (IMMV) spread in bulbous iris. In the iris trial, significant reductions in virus spread were noted for all treatments, with the combined treatment of mulch and insecticide giving the best virus control. However, with little virus spread there were no significant treatment effects on TBV spread in tulips. Reduced numbers of aphid vectors were trapped over unsprayed mulched than non-mulched plots. Mulch treatments had no effect on stem length or harvested bulb weight while the insecticide treatment (tulips only) and treatments incorporating mineral oil significantly reduced both stem length and bulb weight. This work suggests that enhanced virus management in flowerbulb production may be achieved by incorporating reflective mulches in current virus control strategies.