Conviso beet area will continue to grow in the coming years

The area of ​​Conviso beets in the Netherlands continues to grow steadily – to more than 2025 hectares in 8.000. According to Leon Rommens, agroservice manager at KWS, the interest in the Smart varieties among growers is greater than the current regulated and controlled area allows. "We would like to sell more, but we respect that there is still a brake on it for a while," he says.

Bayer spoke with him about the current state of affairs and the future of the cultivation system.

To start with: how big is the Conviso cultivation in the Netherlands?
"For the coming season, the amount of Conviso seed is limited to 8.000 packs, or 8.000 hectares. In the early order, almost 7.000 packs have already been sold and the remaining 1.000 packs are also expected to be sold quickly. This means that more than 10% of the Dutch area will consist of Coviso beets. Last year, that area was still around 7.000 hectares. So we are steadily growing with Conviso."

Where does the Netherlands stand with the Smart breeds compared to other European countries?
"The Netherlands, like Belgium, is still somewhat reserved when it comes to the use of Conviso seed. Both countries are at around 10%. In countries such as Germany and France, the share of Conviso varieties fluctuates around 25% and in the Czech Republic, for example, the share is almost 100%. However, this does not mean that we are lagging behind in the Netherlands when it comes to cultivation knowledge. I think that we look very broadly at the results of the cultivation system here, and therefore also at the (side) effects that cultivation brings with it. In that sense, in my opinion, we are ahead of rather than behind our foreign colleagues."

When are Smart varieties useful to use?
"The main reason for using a Smart variety is to clear problem weeds. We are mainly talking about goosefoot varieties, but also about dog parsley, thistle and bindweed. This plays an important role, especially in areas with traditionally higher weed pressure, such as Drenthe and the sandy soils along the eastern border, and that is why relatively many Smart varieties are sown."

"Smart varieties are also very suitable for combating wild beets. In practice, this means that even plots that were previously unsuitable for beet cultivation can be reclaimed."

Will all weeds be cleared with Conviso?
"Almost all. Only the Veronica species, including speedwell, are not sufficiently controlled. For complete weed control – and also in connection with risk management – ​​the advice is in any case to Conviso One (foramsulfuron & thiencarbazone-methyl) expandable by 1 l/ha Payment Tandem (phenmedipham & ethofumesate) + 1 oil."

"Last season it was quite difficult to get the beets clean - even with the Conviso system. The rule of thumb is to spray the first time when the goosefoot has two to four true leaves and then again ten days later. Due to the extremely wet weather, this was not successful everywhere. In some cases this led to quite large weeds, which were difficult to control. Ragwort in particular managed to get through on some plots."

Growers also mention things like convenience, flexibility and peace of mind in the business operations as important advantages of Conviso. After all, only two sprayings with the same agent need to be carried out, and the application time is also less critical than with conventional weed control. To what extent do you promote these advantages?
"These things definitely count too, but we don't want to put them too much in the foreground. Our focus is on complete control of (problem) weeds; that is actually what the Conviso system was put on the market for."

"Another advantage that may be less noticeable in practice, but should be mentioned, is the major environmental benefit. Compared to the traditional BOGT system, the environmental impact is no less than 87% lower."

KWS currently only has the Smart Liesa KWS variety on the Variety List. Is there – from KWS - more to come?
"Yes, indeed! For the coming season we have four new Smart varieties available in limited quantities. These are currently still numbered, but next year – when they are candidates for inclusion on the Variety List – they will be given the names: Smart Blomma, Smart Jutta, Smart Justina and Smart Enissa."

"Smart Blomma is resistant to rhizoctonia and additionally resistant to rhizomania, Smart Jutta is resistant to rhizoctonia, beet cyst nematode and additionally resistant to rhizomania. Smart Justine is only BCA-resistant and Smart Enissa only standard rhizomania-resistant. For all four, it applies that they are close to 100 in terms of financial yield. Compared to Smart Liesa, we are moving up a considerable distance in that respect."

What are the risks associated with the Conviso system?
"Our main concern at the moment is with the after-crop; that is, the crop after Conviso beets. We know that the two active substances in Conviso One best be persistent. This can cause damage in the subsequent crop. Our advice is therefore not to grow onions or carrots after Conviso beets. Potatoes are possible, but then a good turning soil cultivation must have been carried out. That is to say: plough sufficiently deep; digging does not work deep enough!"

"Another essential point is the removal of bolters. If you leave them standing – and they form seeds – you will hardly be able to remove them in subsequent crops (in which ALS inhibitors are also often used)."

"It is also important to keep regular seed and Conviso seed well separated. Anyone who uses both systems on their farm must thoroughly clean the seed trays of the seed drill and also the tank of the field sprayer in between. We also recommend a buffer strip of a few meters between regular and Conviso beets. In this way, you prevent a few rows of regular beets from being sprayed away in the event of a little drift."

A major concern surrounding Conviso is resistance to the two active ingredients, both ALS inhibitors. How big is this risk?
"That risk is and remains real. In the Czech Republic, for example, where almost 100% Conviso beets are grown, there are already some problems with weed mutants that are not or less sensitive to ALS inhibitors. We must try to prevent that here in any case. The greatest risks are with growers who – in addition to Conviso beets – also have maize and grains in their cropping plan. ALS inhibitors are also often used in these crops. There are few alternatives in weed control, especially in maize. There are in grains, but you will have to use them consciously. These kinds of things will first have to be better understood by the advisors, but also by the growers."

In recent years, Cosun Beet Company has increased the Conviso area in a controlled manner. What do you think of that?
"Well, we would like to supply more, but we respect the fact that Cosun wants to monitor this closely for the time being. If we are to judge by the enthusiasm of the growers, then there is still a considerable increase in the Conviso area in the pipeline. So there is still plenty of potential for Conviso beets."

Finally, is Conviso the weed control system of the future?
"Difficult question... On the one hand, there are plenty of growth opportunities, but at the same time there are also the aforementioned concerns about resistance formation, among other things. Moreover, it is questionable whether the current active ingredients - and in particular phenmedipham - will remain approved for the longer term. For the time being, however, Conviso is mainly a success story. Hopefully we can continue to say that in the coming years."

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