SAMPLING WEEDS TO TEST FOR HERBICIDE RESISTANCE

72 % of dirty Dora seed tested was resistant to Londax and two populations were tested with suspected resistance to Taipan in 2017. There is currently no detected resistance to Group A herbicides in rice weeds, however, Barnstorm™ and Aura® are listed as High Risk for the development of herbicide resistance. Vigilance with herbicide resistance management is important.

It is important to detect herbicide resistance early in order to make decisions about future chemical and management options. If you suspect a weed population is resistant, then correct sampling procedure is important.

It is important to detect herbicide resistance early in order to make decisions about future chemical and management options. If you suspect a weed population is resistant, then correct sampling procedure is important.

There are several herbicide resistance testing services available. The rice industry has been using Charles Sturt University for surveying weeds for resistance across the rice growing regions so they have developed protocols for assessment for rice weeds. Plant Science Consulting also offers a testing service.

When to collect: When the weed seed is mature.

How much seed: at least 1 cup full of clean individual weed seeds or an A4 envelope full of seed heads. The more seed, the better.

How to collect a sample:

-          Walk across the entire area suspected of resistance and cover the area on several transects e.g. follow a W shape.

-          Collect a similar number of seeds from each plant in order to avoid bias in the sample e.g. collect samples every 15-20 paces.

-          The seed must be completely dry when you send it. Air dry for three to four days to reduce the risk of seed rotting in transit.

-          Place in a sealed bag with an identification slip.

The Charles Sturt University protocol and can be found below.

Information about Plant Science Consulting testing can be found here