Ethyl formate fumigation and nematicidal dip treatments as methyl bromide alternative treatments for. the longtailed mealybug (Pseudococcus longispinus) and the root-lesion nematode (Pratylenchus penetrans) on imported nursery plants

Abstract

The increase in nursery plant trade has heightened the risk of invasions of exotic pests, such as mealybugs and nematodes. In this study, we first evaluated the feasibility of using the currently approved methyl bromide (MB) treatment for imported nursery plants (IMP) against the longtailed mealybug, Pseudococcus longispinus. We then assessed ethyl formate (EF) fumigation as a potential MB-alternative treatment and tested 2 nematicides against the root-lesion nematode, Pratylenchus penetrans C. Additionally, we examined the impacts of these treatments on the quality of the IMP. During commercial trials at an importing port in Republic of Korea, the approved MB treatment of 40 g/m(3) for 2 h for IMP did not result in complete control of P. longispinus. Moreover, the MB treatment caused severe and irreversible damage to the treated plants. In contrast, the suggested dose of EF (35 g/m3 for 4 h) caused significantly less phytotoxicity on the treated plants than did MB, and 66% of tested species that suffered moderate to severe treatment damage recovered within the 30 d post-fumigation period. The efficacy of EF was also confirmed in a commercial-scale trial, suggesting that EF is a feasible alternative to MB, showing similar efficacy on P. longispinus but much lower phytotoxicity. For P. penetrans, dipping plant roots in Allstar or Nemakick at 0.5 ml/L for 1 h or 4 ml/L for 10 min resulted in complete control of P. penetrans with no apparent phytotoxicity on the treated IMP. Together, our results suggest that EF fumigation and nematicidal dip treatment are two feasible phytosanitary measures for use on IMP.