Continue to invest in complete darkness control

"Anyone who makes mistakes in the control of blackbirds can hardly recover. That is why you must continue to invest in the most complete control of blackbirds possible." This is what wheat grower Otto Knottnerus in Nieuwolda (Groningen) and Jan Derks Kloosterboer of Agrifirm say. Together they discuss the current situation surrounding this 'horror weed' and also review all possible cultivation and spraying measures.

"No, we have nothing to complain about at the moment. The wheat came in on time and the crops are doing fine. In that respect, the start was a lot easier than last year. Everyone was able to sow under good conditions here." Otto Knottnerus describes in a few sentences how the run-up to the winter wheat season went. Together with advisor Jan Derks Kloosterboer of Agrifirm – who is also present at the meeting – he discusses the latest developments in wheat cultivation. And they also look ahead to the first cultivation measures for the spring.

A more or less 'obvious' topic of conversation is the approach to blackheads. Knottnerus says that his wheat plots are relatively clean - mainly thanks to his father. "In his time as a farmer, he was always very sharp on blackheads and he still walks through the crops in the spring to manually remove the remaining ones. I am now reaping the benefits of that. Apart from the fact that we experience very little damage from blackheads in our wheat, we can also supply blackhead-free straw. We get a nice bonus for that from our North Holland buyer", says the arable farmer. Kloosterboer also states that an intensive approach to blackheads is essential to keep wheat cultivation on its feet. "Anyone who has made mistakes in the past can hardly make up for it. I know enough plots that are so covered in blackheads that profitable wheat cultivation is no longer possible. Continuing to invest in the most complete possible blackhead control is therefore essential to maintain wheat cultivation", he says.

Creating a false seedbed
According to both men, good darkling control starts with neat ploughing, preferably as soon as possible after harvest. Immediately after that, the crop is harrowed, which creates a false seedbed and gives the darkling plants time to germinate. The germinated darkling is burned off again with Roundup shortly before sowing. According to Kloosterboer, burning off a (successful) false seedbed is a very important basis for darkling control. "We know from research that you can certainly remove half of the darkling plants with this. So it is certainly worth paying a lot of attention to this."

Autumn spraying
Immediately after sowing, the autumn spraying follows (with Herald). Although one spraying is still the standard in his work area, according to Kloosterboer there are now also growers who opt for two autumn applications - especially on plots with a lot of darkness. This is done immediately after sowing and then again shortly after emergence. Conversely, in the autumn of 2023 there were also several plots where no spraying was possible at all due to the wet weather. "We saw a significant increase in darkness there last spring," he says.

According to the advisor, a number of sown wheat plots were even sprayed dead and reseeded last autumn in order to suppress the massive emergence of blackbirds. "Of course, that is a fairly rigorous and expensive measure, but it does prevent the blackbird occupation from becoming uncontrollable."

Spring spraying
As for the spring spraying against darkness (with Atlantis star) it is especially important to be on time. "In an early stage, blackcurrant is most sensitive to Atlantis Star and the effectiveness is greatest. So: as soon as blackcurrant starts growing again, you have to spray as soon as the circumstances allow it," says Kloosterboer. The start of growth of blackcurrant can be seen because small white dots appear on the roots. "So you really have to go into the field and pull up some blackcurrant plants. That is the only way you really know when blackcurrant is growing again."

Because the period after sowing was quite dry, the advisor expects that the autumn spraying will not be equally successful everywhere. "That is all the more reason to monitor for darkness early in the spring and to spray with Atlantis Star in time."

According to Knottnerus, early spraying is sometimes a thing, because in early spring there are enough reasons not to go out into the fields. "It helps if you yourself notice that the blackthorn is growing again. In that respect, regular monitoring is really useful and you can time the spraying much better."

Another important point of attention during spring spraying is the humidity. According to Kloosterboer, this must be at least 80% to 85% for the product to work properly. Knottnerus indicates that he really focuses on this. "I have a humidity meter myself and I keep a close eye on it on the day of spraying. As soon as the sun starts to shine too much and the RH drops too much, I stop driving - even when it is almost finished. That can be annoying, but I am willing to do that for a good result."

Resistant darkness
The most worrying point in spring weed control is the increase in resistant blackberry. Kloosterboer says that there are plots where more than 80% of the blackberry is now resistant and that the yield is at least halved as a result. "On those types of plots, profitable wheat cultivation has become impossible," he says.

Although Knottnerus is currently not bothered by resistant blackbird, he does see it as a threat. "That is why I am implementing all possible measures against blackbird as completely and precisely as possible", he emphasises once again. One option that is still 'open' as far as he is concerned is to adjust the crop plan, reducing the share of winter wheat from 70% to 50%. "By adding a new crop - such as legumes - you get more possibilities to combat blackbird. If it is necessary in the future, I will certainly consider that", Knottnerus concludes.

This business case is powered by: