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Reducing seed viability of flaxleaf fleabane, feathertop Rhodes grass and awnless barnyard grass

Keenan, Michelle and Werth, J. and Thornby, D. and Walker, S. (2014) Reducing seed viability of flaxleaf fleabane, feathertop Rhodes grass and awnless barnyard grass. In: 19th Australasian Weeds Conference, September 2014, Tasmanian Weed Society, Hobart, Tasmania.

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Article Link(s): http://caws.nzpps.org/awc/2014/awc201410151.pdf

Abstract

In the sub-tropical grain region of Australia,
cotton and grains systems are now dominated by flaxleaf fleabane (Conyza bonariensis (L.) Cronquist), feathertop Rhodes grass (Chloris virgata Sw.) and awnless barnyard grass (Echinochloa colona (L.) Link). While control of these weed species is best achieved when they are young, previous studies have shown a potential for reducing seed viability and minimising seed bank replenishment by applying
herbicides when plants are reproductive.
Pot trials were established over two growing seasons to examine the effects of 2,4-D, 2,4-D + picloram, glyphosate and glufosinate which had been successful on other species, along with paraquat and haloxyfop (grasses only). Herbicides were applied at ¾ field rates in an attempt not to kill the plants. Flaxleaf fleabane plants were sprayed at two growth stages (budding and flowering) and the grasses were sprayed at two stages (late tillering/booting and flowering).
Spraying flaxleaf fleabane at flowering reduced seed viability to 0% (of untreated) in all treatments except glyphosate (51%) and 2,4-D + picloram (8%). Seed viability was not reduced with the first and second regrowths with the exception of 2,4-D + picloram where viability was reduced to 20%. When sprayed at budding only 2,4-D + picloram reduced seed viability in both trials.
Spraying the grasses at late tillering/booting did not reduce viability except for glufosinate on awnless barnyard grass (50%). Applying herbicides at flowering resulted in 0% seed viability in awnless barnyard grass from glufosinate, paraquat and glyphosate and 0% viability in feathertop Rhodes grass for glufosinate. These herbicides were less effective on heads that emerged and flowered after spraying, only slightly reducing seed viability.
These trials have shown that attempts to reduce seed viability have potential, however flaxleaf fleabane and feathertop Rhodes grass are able to regrow and will need on-going monitoring and control measures.

Item Type:Conference or Workshop Item (Paper)
Business groups:Crop and Food Science
Keywords:Seed viability, feathertop Rhodes grass, awnless barnyard grass, flaxleaf fleabane, herbicides.
Subjects:Plant pests and diseases
Science > Invasive Species > Plants > Effect of herbicides
Plant pests and diseases > Weeds, parasitic plants etc
Deposited On:19 Nov 2014 00:42
Last Modified:08 Jun 2015 16:02

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