Dave Moore, Research Manager with Monsanto in Toowoomba, discusses the importance of clearly delineating fields of Roundup Ready and Roundup Ready Flex on farm, because of different application requirements. He stresses the importance of minimising off site drift when making over-the-top applications of Roundup Ready herbicide to these crops.

Dave, in a nutshell, can you just tell us the difference between Roundup Ready and the new product Roundup Ready Flex

You are aware that Roundup Ready cotton  has a CP 4 gene in it, as well as a promoter.  Now that CP4 gene allows an enzyme bypass which allows the production of amino acids in the presence of Roundup.  What we have got with Roundup Ready Flex is an additional copy of that CP4 gene and an additional promoter.  The addition of that promoter allows the enzyme bypass mechanism to be activated in the reproductive stage.  So you have got full reproductive tolerance.

Now are there any restrictions in relation to the timing and method of application of Roundup Ready herbicide to the Flex product?
From emergence through to 16 node, the label states that you can put on three applications of 1.5kg/ha of product.  From 16 to 22 nodes, you can make one application  at 1kg/ha of product, and beyond 60% open, you can go in with 1kg/ha as a pre-harvest application should you need it.  The reasons behind that strategy are driven by MRL challenges particularly for the Japanese market - we want to maintain cotton seed under 10 parts per million. The range of MRL trial work that we have done over the last few years has shown that that is the safest  and the best way to structure a label.

What is the actual reason for not going over the top between 16 and 22 nodes, as the label states?

The reason for that is 16 – 22 node cotton is getting up in size, in some areas you could be getting close to row coverage and there are two distinct things we have thought about its coverage.  If you are going  broadcast over the top we feel that you are not going to get the coverage you need at the base of the plant and on the shoulder of the hill - probably only going to get coverage in the bottom of the furrow at best.  So it is a coverage issue.  We feel that a dropper, just a plain old dropper down the centre of the row with a T piece will give great coverage.  The second issue is that we are really mindful of the amount of Roundup that gets put out, and we feel that at that period of the season it is a way to show stewardship in not encouraging aerial application.

So just summing up quickly then, what is the total number of applications and total quantity of product that you can actually put on a Flex crop?

You can make three applications from emergence to 16 nodes, one application from 16 – 22 nodes and one pre-harvest.  So that’s five applications, and there is a maximum of 6 kilograms per hectare of product that you can use on the crop in any season.

Now mixing up a Roundup Ready field with a Roundup Ready Flex field just after first irrigation for instance, with an over the top application would have dire consequences.  Just describe to us what would actually happen to a crop where that occurred.

 We have done some work with the older technology, the Roundup Ready cotton  where we have made applications up to 60 days after planting at that 10 – 12 node stage, causing  significant  pollen sterility and having a significant impact on yield.  So if you had a Roundup Ready Flex field and by some means you managed to drift on to a non Roundup Ready Flex field or a Roundup Ready cotton field you would see significant pollen sterility and I am guessing significant yield loss.  There are not a lot of Roundup Ready Flex fields out there this year - we just want people to have a look at it, see how it fits into their farming system. Maybe a barrier or be mindful of not putting your Roundup Ready Flex fields too close to Roundup Ready cotton fields would be a really sensible idea.

Going on with that a bit, what is the best way for growers, from a practical point of view, to designate those Flex fields for instance, which are certainly in the minority this year?

We will have Roundup Ready Flex field poles or tags to help identify those fields and they will be available through the Monsanto Business Manager or the growers respective Technology Service Provider so that’s a great way of identifying those fields and just making people aware that there are two different technologies on the farm with different tolerances.  Our overseas experience has shown that there have been incidences of mixups  and I just  hope that growers really keep that in mind this season because we don’t want that to occur.

This season, we will see over the top applications either by ground rig or aerially to cotton that is a lot more advanced than we have seen previously. What are the key things to think about as far as ensuring off site drift doesn’t occur?

I think that communicating with your applicators and telling them that this particular field may have Roundup Ready Flex in it, this field may not have Roundup Ready Flex in it or it may be Roundup Ready cotton.  We are going through an extension program at the moment trying to reach as many of those applicators as possible, particularly the aerial applicators to make sure they understand the differences. As we in Monsanto often say, the product Roundup doesn’t get out of the drum on its own, and human management factors at certain times are very important in drift issues. Minimise those issues by looking at relative humidity, looking at Delta T’s when you are spraying, looking at your wind strength, where that field is in relation to a nearest susceptible sorghum crop or Roundup Ready crop.  Those simple things will help minimise any challenges.

And finally, Flex now gives growers the opportunity to time their herbicide application based on weed stage rather than crop stage.  What are some of the key issues to take into consideration when deciding when that first or that second application goes on?

That’s the real value of this technology - you can really target your applications as you said to the weed size and weed density rather than the crop stage.  I am sure most growers and consultants are more than aware that cotton is not a real good competitor and that during the first 6 – 8 weeks of the crop’s life, it is really critical to maintain a weed free environment.  So all I can say to growers and consultants is have a look at your weed density and have a look at your weed size and probably treat your weeds when they are at the two leaf stage, your grasses when they are at the two leaf stage and don’t be tempted to wait too long because we really want to get that cotton away to the best possible start.

RELATED INFORMATION:

In Facts on Friday of October 26, the CSD Extension and Development Team discuss some of the concerns with glyphosate drift management with the introduction of Roundup Ready Flex® varieties:
http://www.csd.net.au/downloads/fof/Facts-on-Friday-27-10-06.pdf