T Piper

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DPIRD Collections

Grains and field crops


Residue Trials: Breakdown rates have been established for trifluralin at Wongan Hills and Avondale over the past two seasons. The decay curve follows a hyperbolic curve rather than the expected exponential curve with constant half life, probably due to the considerable loss of chemical by volatalization in the first few days, before biological decomposition takes over as the main breakdown factor.

b) Herbicide Incorporation. Du Pont Zl96 fluorescent orange powder at 30 g/m2 could be readily seen when illuminated by 400 yw/cm2 of 365 nm UV radiation, and was successfully photographed on Ektachrome 400 ASA film with a 4 sec. exposure (at night, and with no more than 1/4 moon). c) Leaching of Chlorsulfuron. Leaching has also been shown to occur in Wongan, Avondale and Newdegate soil columns, but these tests have only been done on 15 cm cores, and the limit of leaching is not certain. d) Pasture regeneration. Trials have been laid down at Geraldton, Wongan and Wickepin to measure the regeneration of pasture following the use of herbicides in-crop. The aim is to separate any effect of the herbicide into a residue carry-over and a reduced seed set component, and to see if re-seeding of pastures may be a necessary adjunct to herbicide use. e) Onion weed control. Pre-germination of weeds gave reasonable weed control, some control plots remaining weed free for 3 weeks after seeding. Combined with Stomp ( 1 litre) the results were excellent, with almost complete control of weeds for over 6 weeks. By this stage the onions had passed the 3 leaf stage and would tolerate all post-emergent herbicides.

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Western Australia