Spot spraying or full-field spraying?

The difference between spot spraying and full-field spraying leads to differing opinions among onion growers. Also in the area of ​​nitrogen application, the different Gewastour participants have their own strategy.

Hubert Linders from Nederweert points out the costs of spot spraying: "Around €200 per hectare, that is quite expensive." However, there are also clear advantages to be named. Reinder Hogenhout from Kimswerd explains: "You stop the onions quite a bit with contact spraying, but you don't see that when you spray full-field. In difficult years, you can round off the onions better with less growth inhibition. In addition, you can spray more powerfully in places than full-field. Put that to good use."

Henco Bouma, crop manager at BASF, sees spot spraying as a valuable addition to existing weed control. "It is a great development that is increasingly achieving good results. It is important to have the basics in order with an effective soil herbicide. Spot spraying is mainly intended to tackle the last, difficult to control weeds or potato storage in places."

He emphasizes that spot spraying is especially effective as a follow-up to an earlier, broad control. "Ideally, after a good soil herbicide, you have already gotten rid of 90% of the weeds, and you use spot spray for the remaining 10% to 20%. However, if you treat 80% of your plot with the spot sprayer, you are actually spraying the entire field and the effect and crop damage are comparable, certainly at higher doses."

The degree of crop reaction also depends on several factors according to Bouma. "When using contact agents with higher doses, it is important how far the crop has hardened. And with agents such as glyphosate, for example in potato storage, you run a greater risk. Adjusting the sprayer and the chosen agent really make the difference. Each plot is custom-made.

Student Xam Hage of Aeres Hogeschool Dronten states: "We had a task map made for plots with spot thistle growth. We are now going to treat these in a targeted manner with our full-field sprayer, but then nozzle-controlled, with nozzles at a distance of 50 centimetres. The zones were determined using drone data."

Different approaches to nitrogen application
In the area of ​​nitrogen fertilization, the strategies appear to vary greatly. David de Wit from Lepelstraat has now spread 50 kilos per hectare after an extra gift of 90 kilos. Jacky Dieleman from Philippine indicates that 30 kilos have been applied to his plots. Hubert Linders divided the nitrogen into two rounds of 40 kilos each.

In contrast, Peter Holster from Marknesse is opting for a wait-and-see approach. "I haven't spread anything yet and they are growing like crazy. Today I started fertigation. I'm curious to see what that will do." Reinder Hogenhout indicates that he has already spread 135 kilos, although he expects that little has actually been released. Arjan Jakobs reports that he will administer 200 kilos of NK this week.

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