Most onions are stored neatly, but locally bacterial disease, fusarium and water flakes are causing problems. Kees Jacobs advises to continue to monitor each batch of onions closely. He also has tips for choosing varieties and preparing for the new growing year.
"We had problem batches last year, but there will definitely be some this year too. That's why I want to urge onion growers to monitor their batches closely. Because forewarned is forearmed." Technical sales advisor Kees Jacobs of Syngenta Seeds has mainly seen batches of onions that hold up well in storage in the period after the harvest, but every now and then he sees worrying situations. In particular, the accelerated dying due to downy mildew causes problems in the shed. "In that case, the onions have died upright, so without normal ironing, and the neck has closed before the bulb could lose its moisture. And then you get water skins. As long as there is moisture behind the skin, my advice is to keep heating."
Keep checking and watching
A second culprit of the onions is bacterial disease. Jacobs: "In some regions, a lot of precipitation fell at the end of August, followed by a few warm days. That was a perfect combination for the development of bacterial disease." The advisor knows of batches that were delivered with 25% tare due to bacterial disease. "And for the remainder, you get a penny, which makes it doubly bitter." The last culprit that causes problems here and there is fusarium. "That continues in the pile," Jacobs knows. "If you find fusarium in your batch, there is only one good piece of advice: say goodbye."
To prevent problems, Jacobs advises to regularly take a sample from the batch in different places and then to look at the onions in daylight. "So not in the shed under fluorescent light, but really outside. That will give you the most honest picture. And if in doubt, call in an expert." For the rest of the storage season, Jacobs repeats the golden rules once again: first dry-heat to an RV of 60. Then you can cool down during the season, but keep a constant eye on the RV. If it rises above 80 again, you will have to intervene again with the heater. And if you have planted onions on potting soil to check the MH effect, you must start checking those onions for root formation from mid-December."
New varieties
Syngenta Seeds welcomes several new varieties this season. "Our new red variety Allurion is really going like a rocket", beams Jacobs. He also has news to report in the yellow onion segment. "Last season, the Revelation was planted by a few test users on loam and clay soil and performed very well there. It is hard and skin-resistant and has a strong dormancy. That makes the Revelation perfect for long-term storage. And with its strong roots, it also grows well on soils with a slightly more critical moisture balance."
The latter also applies to Promotion, currently Syngenta's most important variety for loam and clay soils. "You can keep it well until mid-April and it scores high on yield," Jacobs knows. For longer storage, he recommends Motion. "It does have slightly higher demands on moisture management. It is really in its element on slightly lighter, more demanding loam, but if you can irrigate or sprinkle, it also does well on heavier soils. The seed availability of all Syngenta onion varieties for loam and clay soil is sufficient.
Varieties for light soil
Syngenta has two suitable varieties for cultivation on sandy and valley soils. The Starton is very suitable for early sowing on warmer sandy soils. "But it is not suitable for storage. So it is an onion from the field", Jacobs summarises. This certainly does not apply to the latest newcomer, the Reflection. "It is mid-early and suitable for storage. Based on trials, we have very high expectations of the yield level of this variety. Unfortunately, this year we only have seed available for trials and selected test users. Hopefully I can make more people happy next year."
Priming and ploughing
At the end of this last onion update of the year, Jacobs has two more tips: "Don't wait too long to order if you want primed seed. Priming is really taking off. I think we'll go to 75% primed seed next year. And no wonder, because you increase the chance of a smooth and even emergence, especially with early sowing, which is beneficial for weed control."
Jacobs' last point of attention for now is the plot planning for the next growing season. "We have a nice autumn and therefore a good chance to prepare the plot for next year in time. On clay and heavier loam you can now plough nicely. Personally I do not think the onion is a crop for NKG. And on the lighter plots you can still drain or level if necessary and maybe even sow a green manure. You just have to make sure that the onions are in a prepared bed next spring."