CULTIVATION AND TECHNOLOGY More leeway for chemical products thanks to organic fungicide BUSINESS INFORMATION ON BERT AND LEO SCHELLING Bert and Leo Schelling have a 100 hectare crop farm in Goudswaard in the province of South Holland. The cropping plan includes 35 hectares of first-rate table potatoes. In recent years, the Schellings have cultivated the Folva variety and next year, father and son also want to start growing the Melody variety. They have sold their potatoes to the nearby potato merchant Kleinjan for many years now. They store their potatoes in boxes in their own storage facility, which has a storage capacity of 1,500 tons of mechanical cooling, 200 tons of air cooling and approximately 350 tons in a separate area. The type of soil on their farm varies from sandy loam to heavy clay, and has a clay fraction between 15 to 55 percent, sometimes within one plot. Other crops they grow are 55 hectares of winter wheat, 6 hectares of chicory, and 35 to 36 hectares of table potatoes. Depending on the location of the plots, the crop farmers sometimes lease up to 10 hectares of potato land from nearby farmers. cient soil moisture around the tuber initiation and the cultivation of non-susceptible varieties. Infections by Rhizoctonia can be controlled by efficient chemicals such as Moncereen and Amistar. More leeway for extra active substances The Schellings have been growing first-rate Folva table potatoes for many years. A long-standing customer is Kleinjan, a neighbouring potato trading company, who needs the best peeling quality in this variety for the domestic market, and as little active substances as possible during the cultivation period. This is not always an easy task, is the experience of father and son Schelling. Both during the growing period and during storage, a variety of factors could increase the need for more chemicals. Seasons with high Phytophthora pressure or years with potatoes that have extra sprouting-susceptibility potatoes are examples of this. To limit the use of active substances as much as possible, and also to create more leeway for the use of extra chemicals if necessary, four years ago, the Schellings went to look for a remedy that could improve the skin quality of their table potatoes while using as little active substance as possible. They found it at Van Iperen, their supplier in Klaaswaal. This firm introduced the natural product Proradix Agro in 2005. Untreated Proradix is a bacterium that is able to activate the plant’s own defence mechanism. Yield 5 to 10 percent higher ‘This is a product that acts in the same way as Amistar and Moncereen, only it doesn’t register any points as an active substance’, Schelling senior explains. The very first test they carried out with this organic fungicide gave very good results. ‘We had unmistakably better skins and significantly fewer instances of common scab and Rhizoctonia infections. Also, the table potatoes that were treated with Proradix had fewer or no problems with storage diseases such as Silver scurf and Black dot’, he remembers enthusiastically. Moreover, they found that this natural product had even more positive effects. The treated yield was 5 to 10 percent higher than the untreated ones and grading went much more smoothly. Partly as a result of the use of Proradix Agro, the Schellings are achieving a net yield of 55 to 60 tons per hectare with their Folva variety, and sometimes higher with many kilos in the 40 to 70 mm sizes. Among other things, Schelling senior attributes the higher yield to better root formation in the potato plants. Because of these fine initial results, in the years that followed the potato growers gradually started to increase their use of Proradix Agro, and the positive results were always the same. This year the ‘test situation’ was the reverse of the situation four years ago; the Schellings treated 34 hectares with the organic Proradix and 2 hectares without. ‘We have stored the yield of 26 Potato World 2010 • number 2 Pagina 25
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