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Growing onions with HARDI TWIN

Bas Melissant has a packed diary. Having ultimate responsibility on behalf of Triumfus Onion Products (T.O.P.) for growing 750 hectares of onions, cultivated in locations spanning the Flevopolders, Noordoostpolder, Zeeland and Northern France, his schedule is dictated by a lot of travelling, discussions on progress and cultivation control. 500 hectares are cultivated by T.O.P. under its own management; 250 hectares are put out to contract. He sets some time aside for an interview at the offices of the contracting firm Van Oostrom & Hagenvoort in Bant. Melissant: ‘TOP sets its sights high; this requires the maximum input and involvement of its entire staff. Growing onions needs precision. Growth conditions need to be constantly at their best to prevent any loss of quality.’

The expertise displayed by T.O.P. translates into yields that are 15 to 20% above the national average. ‘Long’ onion set varieties can produce up to 47 tons per hectare; round onion set varieties – the Stuttgart types – up to 37 tons per hectare. Impressive figures that demand an explanation. Melissant: ‘T.O.P.’s success in cultivation is based on three factors: making good selections in each region from farms, fields and growers; optimum supervision of the cultivation and the use of advanced spray techniques.

Preparing well is half the battle. Some years ago, we made a critical review of our growers. We decided to continue only with those growers who were able to meet with our quality standards. This meant a combination of expertise and having good, healthy soil at their command. We have to do everything we can to keep the crop healthy, including the use of permanent, professional sprayers, but the precondition is a clean soil. With the assistance of the T.T.W. system, a cultivation control system originating from chicory growing, a log is kept for each plot of land starting from the time of sowing up to the harvest in which all cultivation measures and growth progress are set out precisely, such as plant balance and growth curves. After harvesting, we analyse the crop and fine tune it for a subsequent round of cultivation.’

Spraying measures play a major role in the ‘Ticket-To-Win’ system. Onions are extremely susceptible to leaf spot and mildew. These fungal infections thrive in dense and humid crops.

By using HARDI TWIN, we have perfect sprayers at our disposal which, thanks to air assistance, cover the leaves well with spray, penetrating the plant.

This helps us keep fungal growth under control. We can also achieve greater capacity as a result of air assistance. We are able to drive faster while maintaining sufficient penetration of fine droplets deep within the plant. The spray is pumped, as it were, to the bottom of the plant. The amount of available spraying time is also more when using the HARDI TWIN: a good spray result is feasible up to wind speed 6. An additional advantage of the HARDI TWIN sprayers is that the spray direction can be adjusted. This application is of major benefit in the case of bulky plants prone to lodging.’

A practical example
Melissant underlines the importance of a good sprayer by giving a practical example. ‘In 2005, a grower colleague from the polder used a standard field sprayer to spray 30% more agent than we use, yet his yield lagged far behind compared with our production figures. 2005 was a particularly difficult year with a high risk of mould due to wet growing conditions. As a result of the high incidence of disease, this grower had to harvest earlier than usual which, apart from higher spraying costs, also meant a fall in yield of a good 10 tons per hectare. Thanks to using the HARDI TWIN, we didn’t have any problem in keeping fungal infections under control.’