Wild radish flowers everywhere

Wild radish flowers everywhere

There’s some pretty wild photos getting around on X of wild radish in WA this year. A wet winter in the north has stopped growers getting on paddocks to spray. While the aerial spraying has done a pretty good job, there’s plenty of flowers in crops now.

They are also starting to see a bit of Velocity resistance in this region, which should serve as a warning to other regions.

At least the wildflower tourists are benefiting! They can add radish to their Pattersons Curse pics.

This prompted me to review some of the research on wild radish seed bank dynamics.

You will hear people say that wild radish seed lasts 10 years. This is true, but it doesn’t all last 10 years. About 90 to 95% of it will disappear in 5 years, and the last 5-10% lasts a few years longer.

When I say disappear, there are a few ways that radish seeds can decay. The obvious one is that it germinates, but there’s also some seed that simply rots, and there’s predation by ants and rodents. 

Anyone who has farmed with plenty of radish for a while will have seen ant nests surrounded by old radish pods.

You may have also heard that if you bury wild radish seed (e.g. with soil amelioration) it lasts longer. Also true, but once again, it’s only a small percentage that lasts longer.

So yes, radish seed can last 10 years in the soil, but most of it doesn’t survive beyond 5 years, even if it’s buried.

Next year

With all of this radish setting seed this year we can expect a huge germination next year right?

Well yes and no.

Yes, there will be plenty of radish next year, but it’s the year after (two years after seed set) that we will see truckload of the stuff.

The pod protects the radish seed, and it’s not until this pod is broken down a bit that the radish seed can germinate. A lot of this pod is intact the year after seed set, and it’s the second year and beyond when the pod breaks down and we see the big flush of radish.

I’ve heard farmers say, “I had a lot of radish in crop last year, but I seem to have gotten away with it. My crops are pretty clean this year”.

Sorry to burst your bubble cobber, but next year may be a bit of a mess.

Radish and HWSC

Radish is a great target for harvest weed seed control. The plant holds onto its seeds at harvest, generally pretty high in the canopy. As with all weeds, it will start to drop its seeds soon after harvest starts, but it is generally pretty good at retaining seeds.

You will have read about some radish that has adapted to shed its seeds in the central wheatbelt in WA. This is true, but it’s rare, and if you have a good herbicide regime to go with your harvest weed seed control it will take a very long time for the radish to adapt. 

Mills and radish

One of the great things about radish is it’s really easy to kill the seeds with a mill. Even the bypass mill of a Seed Terminator will kill them. 

Dicot weeds like wild radish or volunteer canola are really easy to kill. Their seed is big enough to hit hard with the mill, and just a crack in the internal parts of the seed are enough to control them.

It is also common to end up with a lot of wild radish pod in the grain tank, but I’m pretty confident that you won’t lose a lot out of the rotor.

Glyphosate resistant radish

It’s now over 10 years since AHRI researchers found the first cases of glyphosate-resistant wild radish in WA. They found three populations of radish with low-level resistance, and the survivors were pretty stunted plants. 

Since this time, there have been no more discoveries, and mixing herbicides with glyphosate and double knocks are doing the job on the hard-to-kill populations.

But, it does concern me that glyphosate is really the only chemical that we are using to control radish in canola in a lot of cases.

Given that not much resistance has developed so far, it’s pretty low risk, but it is a good idea to destroy any surviving radish in canola.

Some growers turn their mills off when harvesting canola because it can be hard going, and they would argue that the ryegrass is under the cutter bar. But radish will be a similar height to the canola, and a bypass mill on a Seed Terminator will kill a good portion of it, so this is a pretty easy option in my book.

It’s pretty easy to have a weed blow out in a wet year like they are having in northern WA, and in the case of radish, it’s pretty easy to do something about it by belting them with a mill at harvest.

The Terminator Agronomist

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