EXCELLENT crop safety and related early growth and vigour, culminating in the highest yield in a farmer demonstration trial, has convinced Brenton Clarke, Primaries Esperance, of the benefits of the new selective pre-emergent herbicide for canola growers, Devrinol-C.
“We know it’s safer (than other standards) and we’re encouraging growers to give it a go this year in some of their more problem paddocks,’’ said Brenton, who is the Operations Sales Manager with the developing CRT business.
“A number of growers have been interested and already bought the product and specifically said they would like to use it in paddocks they are not so happy with.’’
Devrinol-C, from UPL, is a Group K pre-emergent herbicide containing the new active ingredient napropamide, thereby offering a new rotation tool to help manage grass populations in canola. It controls annual ryegrass, barnyard grass, crowsfoot grass, innocent weed, liverseed grass, pigweed, potato weed, redshank, sowthistle, stink grass, summer grass and winter grass.
The product does not control germinated weeds, however it is compatible with a range of complimentary herbicides including trifluralin, atrazine, propyzamide, metazachlor, glyphosate and paraquat, allowing flexibility in weed management programs.
Trials across Australia over the past four years have consistently highlighted the crop safety, longer residual control and yield benefits of using Devrinol-C in canola compared with existing standards.
Brenton said the demonstration trial they coordinated last season was conducted in a loam/clay paddock with a relatively low grass weed burden on a property at Wittenoom Hills, 60 kilometres north-east of Esperance, that has been continuously cropped for about 15 years.
Following an earlier knockdown herbicide application with glyphosate, Devrinol-C was incorporated at sowing at 2 kilograms per hectare with gramoxone knockdown herbicide and compared with propyzamide applications at 1 litre/ha and 1.5L/ha, trifluralin at 2L/ha, also applied in a mix with 1L/ha of propyzamide, metazachlor at 1.8L/ha and other developmental products.
Brenton said the “double knock’’ spray strategy had worked well in the region and growers typically then applied either gramoxone/atrazine, gramoxone/atrazine/trifluralin or gramoxone/atrazine/propyzamide in a mix before sowing.
“Some growers have swung to trifluralin and if they have a bad paddock they go to propyzamide – to get clethodim to then work better,’’ he said.
The main weed target is annual ryegrass, but also brome grass, barley grass and silvergrass.
Brenton said trifluralin was not as aggressive as propyzamide.
“Applying propyzamide post-sowing pre-emergent can be a good way to get a clean result, but with certain conditions you can get crop effect. This was seen in the trial with one of the development products – when the crop came through it had blotches.’’
Bonito canola was sown into the demonstration trial paddock in early May, however, due to the dry conditions, germination did not occur until early June.
Brenton said despite the dry spell, the crop safety benefit with Devrinol-C was highlighted later.
“It doesn’t seem to have the harsh crop effect that can happen with some other products,’’ he said.
“We did NDVI readings at 28 days and then 56 days (after germination) and on both occasions the Devrinol-C treatment had the highest readings. There was bigger cabbage and more bulk in the crop.
“When we looked at vigour ratings, it was also rated nine, whereas the others were rated seven to eight, so we found it to be more vigorous.’’
Grass counts showed limited pressure.
Brenton said he believed the excellent safety with Devrinol-C contributed to the treatment achieving the highest yield at the demonstration site at 1.81 tonnes/ha. Other yields included 1.74t/ha where trifluralin was applied, 1.66t/ha with trifluralin/propyzamide, 1.68t/ha with the low rate of propyzamide, 1.62t/ha with the high rate of propyzamide, 1.68t/ha with metazachlor and 1.69t/ha where atrazine/gramoxone was applied.
“Up to an extra 190kg/ha at $600/t is significant.’’
Brenton said the new chemistry in Devrinol-C would be a valuable tool and it could be used in place of trifluralin or propyzamide in grower applications with gramoxone if another knockdown herbicide was required at sowing.
He said another important feature of the new product for the Esperance region was its medium water solubility and binding to organic matter, allowing it to move in the soil to provide weed control with less likelihood of leaching out of the weed zone.
Devrinol-C has a label rate of 1.75-2.25kg/ha, with the higher rate advised to be used to target high grass populations. It should be applied with a minimum of 80L/ha of water to moist soil.
Further work is now being undertaken with Devrinol-C to assess its effectiveness against wireweed, toadrush, stonecrop, lesser loosestrife, shepherds purse, silvergrass, common chickweed, capeweed, waterbutton, wild oats, wild radish and clover.
Brenton said he was keenly interested in any additional registrations with the herbicide for the area, particularly for weeds like capeweed.
For further information on the new Devrinol-C selective pre-emergent herbicide, growers can contact their local sales agent.