Today (Wednesday 14 July) Bionext sounds the alarm about the high phytophthora pressure. Many organic farmers have to burn the potatoes too early to prevent further spread of the disease. This results in low yields, often a quarter of the normal harvest. The organic sector is therefore putting the cards on resistant varieties.
That sounds logical and also offers opportunities for conventional growers. In practice it just turns out to be unruly. Bionext, the trade organization for the organic sector, mainly points to the limited demand for resistant varieties on the Dutch market, partly because consumers choose the well-known variety names. That is a big risk for the farmer, because the potatoes have to be sold. Therefore, the demand for these varieties must be stimulated.
"You cannot assume that consumers will suddenly buy organic potatoes," says Michaël Wilde, director of Bionext in a statement. "23 robust varieties have been developed in a short time, a huge victory for the sector. If we want farmers to be able to grow these varieties to protect them against the risk of phytophthora, something also has to be done on the demand side. Assuming that the varieties are sold on their own, so it doesn't work."
Resistance has a limited shelf life
According to several insiders, the market demand for resistant varieties is not the biggest problem. Staying one step ahead of the fungal disease is the most important challenge. Phytophthora adapts and can thus break through resistance in the long term. In recent years we have had warm and especially dry summers. The phytophthora pressure was therefore low and the fungus had little chance of infecting crops and thus breaking through resistance.
This is different this year due to the wet weather. The infection pressure is high and due to the rain, conventional growers occasionally have to shift the spraying interval, which means that protection is not always optimal. This gives the fungus more opportunities to break through the resistances. The current varieties with 1 resistant gene are particularly susceptible to this. "You hope that a resistant variety can last as long as possible, but in a year with high disease pressure you know that the chance that resistance will be broken is quite high," according to an expert.
Ongoing process
Insiders point out that it is therefore important to continue developing new resistant varieties. Using current breeding, developing a new variety takes approximately 15 to 20 years. Various breeders are therefore calling for new breeding techniques (gene editing, CRISPR-Cas) to be allowed on the European market. This speeds up the breeding process and makes it easier to develop varieties with multiple resistant genes (which make it more difficult for phytophthora to break through resistance).
Bionext's plea for resistant varieties certainly makes sense, but according to several experts it is not the solution. Keeping Phytophthora pressure as low as possible (including with crop protection products) and the continuous development of new varieties remains important in the fight against the fungal disease.