'The profit is often in starting early with aphid control'

"Although we are not in an area where the first lice come, I am always there early with the lice control. I just don't want to be surprised," says tribal grower Marcel Aling in Vierhuizen (Groningen). The first weeks after emergence are especially crucial and the spraying interval is kept short and strict. Louse killer Sivanto Prime is a fixed value within the spraying schedule.

It is early February and the sun is finally showing itself again after a series of gray days. Seed potato grower Marcel Aling is sitting in the company canteen with advisor Arjen Bijlsma from Hoogland BV and discusses the latest news in arable farming with him. Aling puts his phone on the table with the message that the beet price for 2022 will be over €68 per ton. Both nod with satisfaction, although a lot of 'regulatory matters' have already passed in review that she doesn't like much. "The buffer strips, the eco-scheme… It certainly doesn't make me happy," says Aling. "And the worst part is that there are terribly crooked rules that achieve exactly the opposite of what is intended." As an example, he gives the herd of sheep of a fellow farmer who keeps the sleeper dike within his plots nicely short and at the same time sturdy. However, within the eco-scheme that is a hindrance – and removing the sheep would even result in an upgrade from bronze to silver. "Do you still get it?" he says, shaking his head. Bijlsma also believes that it is becoming increasingly difficult for arable farmers to practice their profession. "Most companies really do have an eye for things like landscape and the environment. But the requirements in this regard are piling up very quickly and are also very vague or crooked. I understand very well that this causes a lot of frustration and annoyance ."

'No concessions to virus control'
When both men look back at 2022, they especially remember the dry spring, when the onions and beets had a very hard time breaking through the top layer. Aling says that sprinkling these crops on his farm is not really an option, because the water is too brackish for this. A crust breaker was rented last year, but according to him it only helped partly. "Many plants didn't come up or fell away, so we even had to overseed some of the beets. It's been a long time since that happened here." According to him, the fact that in the end there were still reasonable returns, feels a bit like 'little consolation'. "The onions have yielded an average of 52 tons per hectare. That's not even that bad in itself. But if you know that we can also get 70 to 80 tons here, then that's a bit of a disappointment, especially when you look at the current market prices. next to it."

Seed potato season went well
While the onion and beet cultivation could have been better, the seed potato season went well. Aling says that he is fully dedicated to the cultivation of logs (PB and S material), together about 40 hectares. He grows most of it for HZPC (including Innovator, Challenger, Fabula, Farida and Sunred), a smaller part for Averis (Avemond and Adelinde). Although the poters also spent a long time in dry soil last season, the precipitation here came at just the right time. In the end, this resulted in a good yield with a lot of numbers and few oversized tubers. As a small blemish on the season, Aling mentions the scab that has taken hold on some (not very sensitive) varieties. "Normally scab doesn't play a role here, but now we have to sort it out a bit more." He also notices that the seedlings are a bit more germ-hungry than normal due to the warm harvest period. "That's why we're just putting them cold a little earlier than usual."

No concessions to virus control
The season has also gone reasonably well in terms of virus control. Because the lice were present exceptionally early, Aling also started combating them very early. "Usually I can see on the rose bushes in the garden when the first aphids have arrived, so we have to get to work. In that respect, I'm on top of things and I don't wait until something is found in the yellow catch bins," he says. his strategy again.

Aling starts spraying when about 30% of the potatoes are above. For the first two to three weeks, a strict three to four day schedule is maintained with mineral oil (1 liter per day) and – if the temperature allows – also a pyrethroid. This is followed by a first round with a louse killer – Gazelle® or Antilop® – and after another two weeks another louse killer is sprayed, usually Sivanto Prime. According to Bijlsma, Sivanto Prime is an important link in virus control. "This systemic agent acts on three different places in the plant, so that it kills aphids very well and reliably. That certainty is very valuable, especially when you are completely focused on stem cultivation, like Aling. Then nothing really should go wrong in the virus control."

Only two active groups
Bijlsma is a bit concerned about the very limited supply of louse killers. "In fact, we only have two active substances left – those of Gazelle and Antiop (acetamiprid) and those of Sivanto Prime (flupyradifurone). Although there are no indications for this yet, the risk of resistance developing with these two substances remains very real. that the pyrethroids seem to be becoming less and less effective and therefore less and less can be expected from them. All in all, we are walking a very thin line with aphid control in seed potatoes."

Aling adds that after the ban on Actara (which could be used as a soil treatment until a few years ago) and next year the (probable) ban on Vydate® (which has a side effect against lice), it will become more difficult to control the lice anyway keep under control. "Starting with clean seed potatoes was already very important, but it will become even more important in the future," he says. He also emphasizes once again the importance of a sharp selection. "As a company, we are very strict about this, with a maximum of 20 hectares per person and then also select five days a week. And we will not make any concessions to that in the coming years!"

Straw against lice
In the coming season, Aling wants to apply a straw cover to two to three hectares of seed potatoes as a test. In addition, the (yellow) color of the straw should disorient the aphids, so that they do not land on the crop. "French trials have shown that this can lead to a significant reduction in lice and virus. That's why I'm going to get started with it. But let's be honest: I don't expect miracles from it and I'm also a bit worried against the extra work involved. I just hope that it will provide some new knowledge about aphid control, because we can use that very well," is how he motivates his choice. Bijlsma also does not expect that a straw deck will be the solution against virus, although he welcomes the initiative. "If you do the test, I will provide two lice traps, so that we can actually determine the differences between straw and not," he promises.

As a structural solution, Bijlsma would prefer to see (even) more work being done on breeding for virus resistance. "In my opinion, that is the key to the future – with or without the help of new breeding techniques such as Crispr-Cas", he already looks ahead. In the coming years, however, the key will remain with a tight and conclusive spraying schedule with mineral oil and chemical lice killers. "Because let's be very clear about that: without chemistry we won't make it in seed potato cultivation."

^{Gazelle® and Antilop® are registered trademarks of Certis Europe
Vydate® is a registered trademark of Corteva Agriscience}

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