Abstract
SUMMARYLaboratory investigations were made into the effect of cultivar type, prior cold storage, fumigation temperature and methyl bromide concentration, on the efficacy of a fumigation treatment to control Liriomyza trifolii in chrysanthemum cuttings. The tests related to the standard quarantine treatment used in the UK to control Spodoptera littoralis on imported chrysanthemum cuttings: cold storage for 2 days at 1 – 2°C followed by methyl bromide fumigation at 15°C with a concentration time product (CTP) of 54 g h/m3. L. trifolii larvae, within detached leaves, and 1 – 2 and 2 – 3 day old pupae, were treated. Methyl bromide concentrations of 6·75 or 13·5 g/m3 were used to achieve a range of CTPs and thus obtain accurate dose‐response lines and estimates of the LD99 and LD99·9 for each insect stage. Fumigation temperatures were 8, 11 or 15°C.Efficacy of the standard treatments differed between the three cultivars tested, but the LD99 for larvae remained below 54 g h/m3. Decreasing fumigation temperature to 11°C or less increased LD99 values for larvae and pupae and substantially increased variability. There is therefore little scope for using fumigation temperatures of less than 15°C for quarantine purposes. Omitting the cold storage treatment prior to fumigation did not significantly affect efficacy of fumigation. Reducing the methyl bromide concentration from 13·5 to 6·75 g/m3 did not significantly affect the LD99 for larvae but significantly reduced LD99s for pupae.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call