Italian citrus grower Giovanni Battista Spanò will combat the citrus nematode, Tylenchulus semipenetrans, with natural methods involving sowing and green manure of the radish cultivar Defender. The nematodes cause slow decline of citrus.
“Nematodes and fungal diseases of the soil are a problem that can be easily solved without using harmful chemical products,” says Spanò. “We can just exploit the natural properties of some cultivated species. The cells of Defender horseradish contain glucosinolates and the enzyme myrosinase in separate structures. When the cell is broken by the nematode or by the cutting of the cover crop through a mechanical action, the two molecules come into contact, forming the glucosinolate-myrosinase complex. In presence of water, this complex forms glucose and isothiocyanate, which determines the nematicide action. That’s why it is very important to finely chop the Defender horseradish and bury it quickly, so that it can carry out its pest containment action at its best. Another important aspect is that the use of the cover crop manages to contain weeds.”
In an effort to practice sustainable agriculture, Spanò says that several evaluations with agronomists led him to implement this experimental test without using chemicals. He says that in Italy, researchers at the CRA (research center for citrus cultivation) and the University of Reggio Calabria have studied nematode control strategies with the cultivation of biocidal crucifers such as some varieties of horseradish. “My idea is to put in place what is generally done for other crops in the citrus fruit cultivation,” says Spanò.
The citrus grower expects to have more data in a couple of months. “If the results should confirm the expectations in terms of reducing the charge of the nematodes, this practice would represent an extraordinary mechanism of natural defense in the citrus fruit field, without the use of any plant protection product,” he says.
Spanò’s farm is in Calabria, a region in southern Italy. His nematode effort will take place on 8.6 acres of clementine and tarocco (blood orange) grove that he uprooted. “The old citrus plants I’ve uprooted were in a state of senescence. Moreover, there was clear evidence of production and quality level decrease,” he stated. Spanò will replant the acreage with lemon and bergamot orange trees, based on market needs.
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