New Zealand Journal of Crop and Horticultural Science
abstracts
Efficacy of ethyl formate and ethyl acetate for the control of onion thrips
(Thrips
tabaci)
C. W. van Epenhuijsen
D. I. Hedderley
K. G. Somerfield
D. W. brash
New Zealand Institute for Crop & Food
Research Limited
Private Bag 11 600
Palmerston North, New Zealand
email: vanepenhuijsenk@crop.cri.nz
Abstract 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
2.7 g/m3 after 2 h. Treatment of thrips-infested onions (Allium cepa)
with 160 g/m3 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
756 g/m3 ). 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/m3 . The highest dose of ethyl formate tested
on eggs (27 g/m3 for 2 h) in small pieces of leek gave marginally lower nymph counts
than the untreated control. Ethyl acetate at rates of 94 and 120 g/m3 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.
Keywords ethyl formate; ethyl acetate; fumigation; Thrips
tabaci; onion thrips
New Zealand Journal of Crop and Horticultural Science, 2007, Vol. 35:
267–274
0014–0671/07/3502–0267 © The Royal
Society of New Zealand 2007
H05155; Online publication date 15 May 2007. Received 7 December 2005;
accepted 8 October 2006
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