Crown-MH as a weapon against nematodes in starch cultivation

Nematodes are a major and ever increasing problem in potato starch cultivation. This subject was therefore fully discussed during the tour of the Starch Days recently organized by Avebe at WUR experimental farm 't Kompas in Valthermond. Preventing storage plants between crops is one of the options for curbing population expansion. An important weapon that can contribute to this is the means Crown MH, as could be heard during the tour.

As an Optimeel analyst at starch processor Avebe, Tom Maathuis has a great deal of in-house knowledge about the various varieties that are used in the test fields on experimental farm 't Kompas. Whether it concerns nitrogen fertilization or the individual properties, he has them all ready, as the tour on the Starch Days shows. He also regularly discusses the subject of nematode resistance and control. Growers such as Averis, Sloots, Mencke and ZAP/Semagri are constantly looking for resilient varieties, he tells visitors. "It won't stop for a while, because new nematode species keep appearing. Moreover, resistance breakthroughs regularly occur. One of the main reasons is the close cultivation rotation of one in two and in many cases also one to one in the peat-colonial cultivation area." knows Maathuis.

Unnoticed Population Expansion
When naming one to one, the analyst is of course referring to the problem of potato storage. "After each harvest, so many tubers are left behind every year that the plants that grow here in the following year unnoticed contribute to further population growth of the eels." However, something can be done about this, says Maathuis. At one of the test fields during the tour, he gives the floor to cultivation specialist Fokke Smit of Certis Belchim especially for this subject. Smit explains that, in close collaboration with Avebe, a trial with the drug was conducted here within a three-year project Crown MH has been constructed. It contains the active ingredient maleic hydrazide, usually abbreviated as MH. In the cultivation of table and chip potatoes, the agent is now commonly used as a sprout inhibitor, he explains.

Correct time of administration is crucial
Because these growers already spray Crown-MH during the field period, the tubers already have a sprout inhibitor in them before they go into the storage shed, Smit explains. Since the sprout inhibitor is already in the tubers before harvest, this also applies to tubers that are left behind in the field. A second effect of the product is therefore that the share of storage plants is significantly reduced in the following cultivation year. And that's what the trial with starch potatoes is about, says the cultivation specialist. Here is in the starch varieties Altus, Festien, Saprodi, Seresta, Avarna, Axion, BMC and Supporter in the previous year Crown MH administered.

The correct time of application and the weather conditions are very important for proper operation, emphasizes Smit. You should spray the product about five to three weeks before haulm killing. The crop must still be in full growth if the active ingredient is to reach the tubers completely. It is also important that the foliage remains dry for at least ten hours after spraying. If not, the recording is insufficient.

Up to more than 90 percent reduction
Smit can demonstrate in the test fields what the effect is of too much rain after application. After treatment of the first four varieties mentioned, a heavy rain shower fell within three hours after spraying. The other four remained dry after treatment. The difference became clear after measuring the amount of active substance in the tubers: we measured a 50% lower content in the fields that had rained too quickly. Then you will see that the smallest tubers have germinated after all and provide storage plants. If the spraying is successful, you can count on a huge reduction in the number of storage plants as a starch grower. The extent to which differs per variety, but you can count on a reduction of 70% to over 90%, Smit guarantees. He points, for example, to a few rows of the BMC variety in which only 10% of the tubers treated with Crown-MH have germinated.

Cauliflower-like structure
Smit also shows the visible effect of successful operation on a few tubers that he takes out from the back. "Look, all the tubers in which Crown MH is well absorbed show a cauliflower-like structure", he shows the visitors. Smit urges the starch growers to always apply the recommended dose of 11 liters per hectare, as indicated on the label. "A lower dose will not give you the intended effect and you can just as well leave a spraying", he emphasizes. He also adds to refrain from spraying if it is too dry around the optimal application moment and the crop growth has come to a standstill. "Even then Crown-MH does not work sufficiently", he knows from experience.