In-crop control of high density weed populations following poor in-crop control in cereals is a challenge for chickpea growers that requires careful planning of herbicide use across the rotation and implementation of harvest weed seed controls, fallow treatments and pre-emergent herbicide use.
Managing in-crop weeds in pulses
by Tim Weaver, Pulse Australia (Industry Development Manager – NSW)
Some growers are facing a challenge to manage high density, herbicide resistant annual ryegrass populations in chickpea this year, potentially limiting yield.
Grain Orana Alliance (GOA) surveys have shown over 90 per cent of samples having resistance to Group B herbicides such as Logran and Glean, and over 70 per cent of samples resistant to Group A herbicides such as Axial (a den) and Hoegrass (a fop).
This level of resistance has led to high density populations of annual ryegrass surviving in-crop control in cereal crops and placing significant pressure on the limited herbicide options in chickpea.
Where pre-emergent (residual) chemistries have been successfully applied in chickpea crops there should be a noticeable level of control however chickpea is not a strong competitor with weeds so any survivors need to be controlled to prevent seed set.
The in-crop post-emergence grass-selective herbicide options for use in chickpea crops include haloxyfop (e.g. Verdict) apply 2-leaf stage to flowering, fluazifop-p (e.g. Fusilade Forte) apply up to 7 weeks before harvest, quizalofop-p-ethyl (e.g. Elantra) apply after 5-leaf stage and up to 12 weeks before harvest, clethodim (e.g. Status or Select) apply up to full flower and propaquizafop (e.g. Shogun) up to 12 weeks before harvest. All these options are Group A fops and so may already be challenged if the annual ryegrass is resistant to Hoegrass.
Weeds present in the crop can be tested for susceptibility using a ‘quick test’. This involves digging out seedlings and sending them to the testing service. The weeds are then trimmed, potted, regrown and sprayed providing results in 4 to 6 weeks. Testing early for susceptibility will identify what products could be applied during the season and provide adequate control. Contact Peter Boutsalis at Plant Science Consulting for details. http://www.plantscienceconsulting.com
Chickpea is not a good candidate for croptopping because it generally matures too late and too much yield would be lost. Other harvest weed seed control options such as narrow windrow burning can drive down seed numbers and improve the chance of success with fallow treatments and pre-emergent herbicides going into the next cropping season. Using other chemistries in cereal crops will also help preserve efficacy of the Group A herbicides registered for chickpea.