Diversity and Management Strategies of Plant Parasitic Nematodes in Moroccan Organic Farming and Their Relationship with Soil Physico-Chemical Properties

Abstract

Organic farming has been increasing steadily over the last decade and is expected to grow drastically in the future. Plant parasitic nematodes (PPNs) are known as one of the most important pests attacking various plants in conventional and organic farming systems. A survey was conducted in January 2019 to determine the occurrence and diversity of PPNs, their associations with soil properties, and to assess their management methods in organically farmed fields in Southern Morocco. Twelve genera of PPNs were identified in soil and root samples collected from 53 organic fields, including Meloidogyne, Pratylenchus, Helicotylenchus, Tylenchus, Tylenchorynchus, Criconemoides, Trichodorus, and Xiphinema. The root-knot nematodes (Meloidogyne spp.) and the root-lesion nematode (Pratylenchus spp.) were the most prevalent PPNs. Vegetable crops (bean, onion, and tomato) had high nematode diversity indices compared to some aromatic and medicinal crops, including the Shannon, Evenness, and plant parasitic index (PPI). Our study underlined that several PPN genera were significantly correlated with soil physico-chemical properties, in particular, soil structure and organic matter. Therefore, it was concluded that soil properties have a considerable impact on PPN communities in organic farming systems located in Southern Morocco. There are numerous strategies for the control of PPNs in organic farming systems.

Biodiversity of Nematode Communities Associated with Wheat (Triticum aestivum L.) in Southern Morocco and Their Contribution as Soil Health Bioindicators

“…It was shown that soil texture (mainly sandy and clay content) affected nematode occurrence. A recent study conducted by Krif et al [80] reported that many PPNs populations were strongly correlated with soil clay, sand, and silt content in vegetable crops, while Van Diepeningen et al [81] demonstrated the same effect in both conventional and organic agricultural settings, and they found a prominent impact. In addition, this correlation could strongly define PPNs population structures [82,83].…”

Vertical Distribution of Plant-Parasitic Nematodes in Sweet Potato

“…The losses resulting from RKN infestation may be variable depending on the nematode species (Overstreet, 2009). Root-knot nematodes also cause necrosis and predispose the storage roots to cracking, which reduces their market value (Lawrence et al 1986). High population density of Helicotylenchus reduces the weight of tubers, roots, and shoot biomass (Lopez et al, 1981).…”

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“…On the other hand, in Morocco, such studies have revealed a greater diversity. There, 12 genera were found [15]. Root-knot nematodes of the genus Meloidogyne and the genus Tylenchorhynchus were detected in 100% of the sites surveyed.…”