Managing nematodes in Egyptian citrus orchards

Abstract

AbstractBacked by its Mediterranean climate, fertile soils, cheap labor, and geographic location, Egypt ranks high among citrus producer countries. These factors can collectively offer early fruiting and long harvest season, good quality, low production costs, and closeness of export markets. However, citrus trees are attacked by many plant-parasitic nematode species in Egypt and abroad; all but one, the citrus nematode Tylenchulus semipenetrans, of which are of limited distribution. Tylenchulus semipenetrans impacts the size and quality of citrus yields differently under various conditions, but guidelines have been published to help interpret soil sample results. Other species such as migratory endoparasites (lesion nematodes), sedentary endoparasites (root-knot nematodes), and several species of ectoparasitic nematodes (spiral and stunt nematodes) can damage citrus in Egypt. Yet, due to their limited distribution and very low population densities in citrus orchards, their damaging level is uncertain or not believed to cause significant damage of citrus yield. Clearly, T. semipenetrans interacts differently with other plant pathogens often found in citrus rhizosphere. While its infection to citrus seedlings can reduce subsequent infection of roots by Phytophthora nicotianae, it can increase the virulence of Fusarium solani. Therefore, issues closely connected with citrus yield losses are presented herein. Perspectives for management of nematodes associated with citrus in Egypt were discussed in the light of their economic importance, sampling accuracy, phytosanitary measures, ecology, and biology. Cultural practices should tackle other citrus problems before managing these nematodes.