The non-structural dry matter content of onion bulbs consists principally of fructose, glucose, sucrose and fructans.

Ethanedinitrile (EDN syn cyanogen EDN Fumigas) is a relatively new fumigant with the potential to disinfest quarantine pests from radiata pine (Pinus radiata D Don) logs and sawn timber for export This research evaluated the effects of dose (20 g/m3 or 50 g/m3) timber moisture content (green or kiln dried sawn timber) endgrain sealing (sealed or unsealed timber endgrain) and load factor (11 or 44) on sorption of EDN fumigation chambers Chamber loading significantly influenced sorption with higher loading resulting in greater sorption Changes in the dose of EDN did not affect the sorption pattern Increased moisture content and endgrain sealing both reduced sorption but these effects were relatively small and the differences in sorption patterns caused by moisture content or endgrain sealing decreased over time

The surface area of a log is the most important factor influencing MB sorption and desorption rates, with greater surface area resulting in greater (de)sorption rates. Sorption data can now be combined with insect toxicity data to estimate a minimum effective dose of MB for further evaluation, while desorption data can be combined with fumigant plume modelling to assess worker safety. © 2016 Society of Chemical Industry.

High sorption by Pinus radiata (D. Don) logs may limit insecticidal efficacy of a fumigant by rapidly removing it from the treated headspace. The sorption characteristics of a new fumigant, ethanedinitrile (EDN), were quantified for recently harvested pine logs, and the robustness of a proposed EDN sorption model developed for sawn timber was tested. Over a 10-h period, average concentrations were 17.3% � 0.7 of the initial dose for logs with sealed ends and 9.4% � 0.4 for unsealed ends. This is a high rate of sorption compared with other fumigants, such as methyl bromide. A proportional drop in headspace concentration over time was consistent for the two doses (20 and 50 g/m 3 ) evaluated, confirming that EDN sorption is influenced by the dose applied. Bark cover did not significantly influence EDN sorption. A revised sorption model for EDN is proposed here.

Both adult and juvenile thrips (Thrips tabaci) reared on leeks (Allium ampeloprasum) were very susceptible to the effects of ethyl formate. Complete control was achieved at concentrations as low as 2.7g/m 3 after 2h. Treatment of thripsinfested onions (Allium cepa) with 160 g/m 3 of an aerosol containing 16.7% ethyl formate by weight in carbon dioxide killed nearly all adult thrips immediately after treatment. An assessment 9 days after treatment indicated that eggs had not been killed by the treatment. No residues of ethyl formate were detected in onions collected 1-28 days after treatment following application of two very high dose rates (236 and 756g/m 3 ). Ethyl formate had no effect on skin colour, onion firmness, or incidence of rots, and no visual signs of phytotoxicity were evident on onions treated with concentrations up to 324 g/m 3 . The highest dose of ethyl formate tested on eggs (27 g/m 3 for 2h) in small pieces of leek gave marginally lower nymph counts than the untreated control. Ethyl acetate at rates of 94 and 120 g/m 3 significantly reduced the numbers of emerging nymphs compared with those emerging from an untreated control. This fumigant is a similar compound to ethyl formate but may be less phytotoxic. When ethyl formate is used for disinfestation of heavily infested onions, a second treatment is needed to control the egg stages.