Methyl bromide fumigation of weed seeds in compressed coco peat
In February 2008 weeds were found growing from imported coco peat and a Ministry of Agriculture and Forestry Biosecurity New Zealand response initiated A controlled trial was undertaken in 2008 to determine if methyl bromide (MeBr) could be used as an effective treatment to devitalise potential weed seeds in compressed coco peat blocks Five weed species were trialled Digitaria sanguinalis Mollugo nudicaulis Panicum miliaceum Cleome rutidosperma and Amaranthus viridis Four replicates were used in the fumigation trial with each replicate placed inside one of four 128block pallets of coco peat Coco peat blocks near the middle of each pallet were removed and split and weed seeds of all five species placed in the centre of the blocks before the pallets were repacked for fumigation Results showed seed growth for Mollugo nudicaulis Panicum miliaceum and Amaranthus viridis after treatment with an application rate of 240 g/m3 of MeBr for 72 h Temperature was maintained above 16C This result indicated that MeBr fumigation of compressed coco peat is not a sufficient treatment to devitalize all weed seeds in compressed coco peat