Lack of regrowth means onion harvest is not a top crop

"We see that the early plots have died off quickly this summer, which ultimately costs a lot of yield," advisor Paul Hooijman of Delphy summarizes. In his work area (Central Netherlands) this is largely due to the impact of downy mildew, 'but that phenomenon is visible nationwide', he knows from his colleagues. Kees Jacobs of seed supplier Syngenta also confirms this. "Roughly speaking, you can say that the further you farm from the coast, the higher the mildew pressure. You have less wind and more shelter around a plot, which means the crop stays wet for longer."

However, onion experts on the coast also see mildew wreaking havoc in the onion plots. "We know that mildew is more likely to become a problem during a long period of leaf wetness," says Arjan Bos of Hazera. "These plots in particular are often sown early, which caused mildew to appear early. Heavy showers before the cutting also accelerated this process."

Large spread
At the end of August, the harvest of seed onions got underway in all parts of our country. The spread is large this season, which partly depends on the sowing dates. Onions were sown in March, but also far into May. This results in the harvesting and loading taking place very spread out. "Some late plots have not even started to iron yet," Jacobs observes. "That could be due to heavy weed control, which caused the onions to stand still for a while at the end of May and the beginning of June. Problems with the structure and low nitrogen availability are also mentioned as reasons for disappointing growth.

There are plots of land throughout the country that do not want to iron at all, so noticed Bart Schriever of De Groot en Slot previously at Boerenbusiness. Whether mildew can also provide a nasty surprise in storage is still guesswork. "Plots that have not been ironed but do die can, in a heavy rain shower, be confronted with bacteria," Jacobs explains. In addition to the mildew problem, which is more difficult to control partly due to the lack of the fungus fighter Mancozeb, the onion experts also see stemphylium that causes the foliage to die prematurely. "You have to be on top of it with disease control," Bos observes. "That means starting on time and not stopping too early. Where that has not gone completely well, you see the consequences immediately."

Varying Yields
It is still early to make firm statements about the yields. Johnny Remijn, advisor for Delphy in Zeeuws-Vlaanderen, uses 35 to 50 tonnes per hectare as an estimate. "The yield spread is not only due to the sowing time", he explains. "Drought also plays a role. Many plots have therefore been irrigated at least once." At the moment, harvesting on clay soil is also often at a standstill because the soil is too hard. Growers are hoping for a rain shower. Arjan Bos also sees this considerable spread in the north of the country. "We see plots of 45 tonnes, but also outliers far above. On average, the onions are finer this year, because the number of plants is not everywhere after losses this spring. The onions have also not grown as coarsely due to fewer growing days."

On the Syngenta test fields, Jacobs sees yields of between 50 and 60 tonnes gross. "That's not easy for me, considering the emergence and the number of plants," Jacobs explains. "Growers in East Brabant and North Limburg, who have now delivered their onions from the field, are making similar noises. Due to the very high temperatures, harvesting was no longer possible in this region from Wednesday onwards, to prevent sunburn." Locally, hail also caused some damage at the end of August. In eastern Flevoland and around Emmen, this is the case, with harvested onions sometimes even being hailed in the swath.

MH spraying
The rapid dying off not only has an impact on the yield, insiders also express concerns about the quality. There are doubts about the uptake of MH in particular on plots that have died off prematurely. After spraying with this germination inhibitor, you need two weeks of active sap flow. "It is good to monitor dubious batches closely during storage," says Hooijman. "If no germination is visible in November, then everything is fine. If that is not the case, then these batches cannot be stored for long." He has come across less fusarium infestation in his work area this year than in recent years. "We know from experience that a late infestation in August can cause a lot of trouble, but because the first half of the month had relatively moderate temperatures, this will hopefully not be too bad."

It is difficult to say what percentage of the seed onions has been harvested. It is estimated that this amounts to 15% to 20% of the area. Depending on the weather, growers hope to make a big difference this week. This makes the harvest feel a little ahead of other years. "Some people quickly drive their onions in before the predicted thunderstorms, while others are waiting for the rain," Bos notes. "It is important that the batches are blown on vigorously. We regularly come across rotten onions. Fusarium is visible on plots that suffer from a poorer structure. An onion that has been affected by fusarium also no longer evaporates moisture, which means that good drying in the shed is definitely a requirement."