Potassium phosphonates work against phytophthora

Arable farmer Bert den Boer eagerly makes use of the multiple effects of the potassium phosphonates in the new phytophthora agent Zampro PlusThe fact that potassium phosphonates stimulate the plant's own defenses is important to him. "We're increasingly moving in that direction with crop protection."

In Zonnemaire on the Zeeland island of Schouwen-Duiveland, Bert den Boer runs an arable farm of approximately 70 hectares on good loam soil, with 25 hectares of seed potatoes as his main crop. He also grows winter wheat, set and seed onions, sugar beets, chicory, celeriac, and spring barley. Irrigation is not an option for him, as there is no fresh surface water available on the island. But that's no reason for the Zonnemaire arable farmer to sit back and wait patiently for the season to unfold. The money he can't invest in irrigation is invested in other measures and inputs to optimize the performance of his crops. "I try to get the most out of it with the maximum input," he explains his approach.

With an annual supply of 750 tons of compost and green manure cultivation on 30% to 50% of his acreage, Den Boer takes good care of the soil. He is also an avid user of foliar fertilizers and plant strengtheners (biostimulants). He applies humic and fulvic acids to his seed potatoes, along with two different starter fertilizers for optimal phosphate levels. He tries to confuse the aphids that threaten his mini-tuber crop with straw between the ridges, and when spraying, he tries to spare the aphids' natural enemies.

Stimulate your own defenses
Den Boer also has his own thoughts on the approach to phytophthora. "Since 2023, we've been combining and alternating active ingredients for resistance management. That was a good move, and I immediately embraced it. But I don't think it's the long-term solution. More is needed. We'll have to make progress in variety development and make more use of the plant's natural defense mechanisms." 

Den Boer was therefore pleasantly surprised when he heard from his advisor Lein de Visser of FarmPlus last year about the arrival of the new phytophthora fungicide Zampro Plus With the active ingredients Initium and potassium phosphonates. "I remember the potassium phosphonates in Zampro Plus from the time they were used as fertilizer. Seed potato trials back then already demonstrated that potassium phosphonates positively influence tuber numbers. I used it in my seed potatoes back then, too. But potassium phosphonates also have a multi-factor effect that's somewhat similar to the Mancozeb of the past. On the one hand, potassium phosphonates inhibit the phytophthora fungus, but they also stimulate the potato plant's own defenses."

Lein de Visser, who is also present at the conversation, agrees with Den Boer's story: "The great thing about potassium phosphonates is that they activate a process in the potato plant. And the phytophthora fungus can hardly become resistant to that. So with Zampro Plus In your schedule, you're actually protecting the current chemistry." Den Boer used Zampro Plus on T2 and T4. "Three applications are also fine," says De Visser. "Zampro Plus has a strong systemic effect and is therefore best suited for the rapid foliage growth phase. The product reaches everywhere and has a long-lasting effect."

Zampro Plus in brief

• Two active ingredients in a ready-made product
• Unique targets on the fungus
• Very suitable for the rapid foliage growth phase
• Activates the body's own defenses
• Upward and downward systemic