Research by Western Australia's Department of Agriculture has demonstrated that tank mixes of fungicide and herbicide damage chickpeas.

A robust package to counter Ascochtyta Blight in chickpea has been developed by the Department, however this requires extra passes over paddocks to apply fungicides. Consequently, growers have inquired about the potential for blending herbicides and fungicides to reduce the number of spray operations required.

Department Research officer Martin Harries said that the research into the tank mixing was part of a Grains Research and Development Corporation funded project to develop better agronomic packages for pulse crops.

"If commonly used herbicides and fungicides could be tank mixed and applied together this would save time and money for growers. Growers had inquired whether these products could be combined even though the label recommendations advise not to," he said.

Chickpeas were grown in pots to the four to five node stage and then sprayed with tank mixes of common herbicides and fungicides. These included Bravo®, mixed with Broadstrike®, Select® and Fusion®. These mixtures were all tested with and without the addition of a crop oil, Hasten with Broadstrike® and Supercharge® with the grass selectives."

"The results were quite easy to see soon after spraying. The tank mixes caused the leaves to burn back from the tips and when oils were added leaves fell off the plants stripping entire branchlets," Mr Harries said.

"Unfortunately, all of the tank mixes really set the plants back. Even with regular watering the damaged plants did not catch up to those sprayed with only Bravo®," he said.

"With the plants dying back from the tips, they could be more open to infection by diseases, wasting the money spent on fungicide, and lost yield."

Mr Harries said the research showed weed control and ascochyta control spray operations would have to be kept separate to ensure crop safety and that label recommendations need to be adhered.

Future research included plans to continue testing granular formulations of herbicides with fungicides to determine whether these combinations are safer.