'Signum strong against alternaria and sclerotinia'

Signum continues to live up to its reputation as an effective fungicide in potato cultivation. "In combination schemes against alternaria you even see the importance increasing," reports Bert Westhoff, potato specialist at BASF. Signum has been showing reliable action against sclerotinia for years. The pyraclostrobin in Signum is also known as a plant enhancer that supports the potato plant's own defenses.

"Today you see that combination schemes against alternaria are just as strong as the solo remedies of the past. Growers who still use the alternaria remedies solo in a scheme are doing themselves a disservice," says Westhoff. "It has always been true that the effectiveness of fungicides gradually decreases, but that does not mean that good control is no longer possible." In various tests and practice, Westhoff sees that preventive schedules with Signum and still offer Narita excellent protection.

Alternaria schemes
For alternaria schemes in ware potatoes, Westhoff recommends starting with 2 times Signum. “The first spraying should then be carried out at the beginning of flowering,” he says. "Usually this is around the first week of July. The second spraying can take place in the third week of July. Afterwards, it is best to do a block of Narita twice in the first and third week of August."

That he Signum at the front has a reason. "Pyraclostrobin in Signum is approved as a plant enhancer. However, few people know that. This substance boosts the plants' defenses. The sooner you apply Signum, the stronger the effect." Another fact is that the blockwise application (2+2) gives a better result, compared to Signum and Narita. If the growing season is long, he advises finishing with Narita (or, in the case of a very long growing season, Signum and Narita).

Start earlier
The advice schedule for a strategy against sclerotinia is the same, but Westhoff recommends starting earlier. "With sclerotinia it is important that you touch the stem. So it is important to start before the crop closes." That advice is completely appropriate this year, because BASF already sent the first sclerotinia warning at the end of May. "The mushrooms are early," Westhoff confirms. "And the conditions for sporulation and infection were already present at the end of May."

Only sclerotinia control is required in seed potatoes. "You can do this with 3 to 4 times Signum keep well under control. It is crucial to start early. At the latest mid-June," says Westhoff. "Then the infection period of sclerotinia usually begins. I know growers who use Signum from the second phytophthora spraying. That's a great tactic. The sooner you start, the longer you will benefit from the physiological effects of the pyraclostrobin."

Non-chemical cultivation measures
Westhoff also points out a few non-chemical cultivation measures. "On light soil, hoeing and ridging is an option. You combat the mushrooms and thus eliminate the source of infection. Growers must also keep an eye on the weeds. Buttercup and dandelion are host plants for sclerotinia." Westhoff has 1 important tip for alternaria: "Provide a vital crop without deficiency symptoms. After all, Alternaria is a weak parasite."