Many diseases develop in summer and Sicily, despite its high temperatures, is not immune. Nematodes are among the pests that cause the most considerable damage.
Root-knot nematodes (Meloidogyne spp.) (Fig. 1) may even cause the total loss of crops. This happens because temperatures in Sicily are mild even in the autumn-winter period. Defences against nematodes is therefore essential.
Fig.1 - Root system of a tomato plant seriously damaged by root-knot nematodes
To better understand the problem, we contacted Giada d'Errico, researcher at the Agricultural Department at the University of Naples Federico II.
Giada d'Errico
"Soil fumigation, solarisation and resistant rootstocks are the main solutions. When it comes to fumigation, 1,3-Dichloropropene is the main molecule used. It needs a national authorisation renewed every year. If performed well, it also enables a second cycle without additional interventions."
"Solarisation has benefits similar to fumigation. Its limit is the fact that results are uncertain, as they depend on the weather - frequent rain keeps soil temperatures down. In addition, the effectiveness of solarisation is limited to 20 cm below ground. Last but not least, it reduces organic matter content, which is very low in Sicilian soil."
Using resistant or tolerant varieties makes it possible to not change agricultural practices and company organisation. The main limits are that resistant cultivars are only available for tomatoes and peppers and that resistance can be compromised by external factors such as soil temperature. In addition, the frequent employment of resistant varieties can favour the development of populations that can attack cultivars with resistant genes.
"Fumigation is therefore a better solution. However, some vegetable extract, biocontrol microorganisms and soil recovery must also be taken into consideration."
Research showed that the different strategies are more successful if they are combined.