The discussion about the use of copper oxychloride in organic ware potatoes heated up last season, as did the phytophthora disease pressure itself. It led to parliamentary questions. This year organic growers are in better shape. Good news, because the curtain is falling for the horse remedy. Agrico puts a red line through copper use and Skal tightens the controls.
Seed potato trading house Agrico is also an important player in organic potatoes. Not only seed potatoes, but also consumer crops. For the table potato market, chips and fries to name a few. The company is involved in the entire chain of organic potatoes. Subsidiary Leo de Kock packages and markets the product.
No copper on resistant varieties
“For the 2017 season, we have instructed growers to no longer use copper oxichloride to combat the fungal disease phytophthora,” confirms Agrico director Jan van Hoogen. “This requirement applies to the Agrico varieties that have resistance to potato blight. The largest breed is Carolus, followed by the Alouette.”
Non-resistant variety is free
Agrico does not impose any requirements for non-resistant varieties. Agria, among other things, is a popular variety in organic cultivation. “The use of copper for fungal control is prohibited in organic cultivation. It may only be used as fertilizer,” Van Hoogen emphasizes again. Since 2000, it has not been permitted to use copper oxychloride for fungal control. For foliar fertilization, 6 kg per hectare per year may be applied. Last year it was shown in Flevoland that this standard was well exceeded in a year with high disease pressure. Contractors drive back and forth with their field sprayers.
Skal closes loophole
Skal, the supervisor of organic production in the Netherlands, confirms that it is carrying out additional checks this year. “The reason for this is not only the situation that arose last year. Last winter, after an evaluation, it was decided to have it checked more often," says Dirk Smits of Certification and Supervision at Skal. “It remains difficult to monitor copper use, because it is permitted as a foliar fertilizer. In the Netherlands we do not have a copper deficiency in potatoes. Growers are obliged to send us a fertilization plan, in which the use of copper must be justified. In practice this means that no copper can be used. The expectation is that this will stop the use of the drug, but it remains to be seen whether this will actually be the case. Farmers can be very creative.”
Seed potato bottleneck
When organic potato growers see their crops ruined, they resort to the last resort. That became painfully clear during the summer of 2016. “You don't often experience a year like 2016,” says Agrico director Van Hoogen. “The last time we saw such a heavy phytophthora infection was in 2007. That shows the frequency. In the future we only want to grow resistant varieties. Our bottleneck is the availability of sufficient seed potatoes.”
Is resistance the solution?
According to critics, resistant varieties are not the cure-all. Resistance can be broken. Especially when new phytophthora strains emerge. Van Hoogen does not think things are going that fast: “We use natural resistance genes, which are found in areas where very aggressive phytophthora strains appear. These do not occur in the Netherlands, but they do in the homeland of the potato, Mexico. Resistance is not easily broken. We also found a leaf of phytophthora on the Carolus last year, but that did not cause any problems. You shouldn't put your money where your mouth is, but with a few 100 hectares of resistant potato varieties, the risk is not great.”
Sector itself to take steps
“Due to the low disease pressure, the subject is less important now,” Smits also knows. “The discussion about whether or not to use copper also occurs within the sector. It is good when the sector itself takes steps. This is done, among other things, by using more resistant varieties.”
Measuring with 2 sizes
After Skal and NVWA announced last season that they could not monitor copper use, Albert Heijn decided to take measures itself. It had the organic products tested for copper residues. It is not known whether it ultimately found it. It decided not to impose extra-legal requirements from the supermarket chain. What is special is that AH will do this for conventionally grown potatoes from 2019. These potatoes must have an Milieukeur, which means that 28 legally permitted crop protection products may no longer be used.