NAME OF THE ORGANISM: Pratylenchus penetrans (PRATPE)

Evaluation continues

Candidate

Pratylenchus penetrans is cosmopolitan and has more than 350 hosts including woody plants (e.g., fruit trees, roses) and herbaceous plants (e.g., potato, vegetables) (Moens & Perry, 2009, CABI, 2021), e.g., Malus is a good host for Pratylenchus penetrans (aaltjesschema, 2019). Also Pyrus spp., Cydonia oblonga, Pistacia vera and many Prunus spp. can be hosts of P. penetrans (Hoekstra & Oostenbrink, 1962; Askary et al., 2012; Merrifield, 2000). Ficus carica is not mentioned as hosts and information of Pratylenchus penetrans on Pistacia vera is scarce (PlantwisePlus Knowledge Bank, 2023; Fatemy, 2009), this could be linked to P. penetrans being a nematode from mostly temperate climates and fig and pistachio being more Mediterranean crops. P. penetrans can complete its entire life cycle within the roots of plants.
Pratylenchus spp. are migratory endoparasites that enter the host root for feeding and reproduction and move freely within the tissue. Consequently, they spend much of their life cycle in roots and are found in soil when the host plants are senescing, stressed or diseased, or when their hosts have been ploughed up after harvest (Castillo and Vovlas, 2007).
P. penetrans occurs mostly on sandy and peaty soil. The transport of infected plants or those growing in infested soils is one of the principal means by which these nematodes are disseminated (Lehman, 1994; Anonymous, 1999). Bare-rooted plants are often contaminated by soil particles which may contain nematodes. Roots can host endoparasitic nematodes that are not removed by washing treatments (Lehman, 1994). In this context, it is essential that the plant propagation material be free of this pathogen (Allen, 1949). Because it can survive in soil, it can be dispersed by land vehicles etc.; within a field by cultivation, and can be introduced to non-infested sites by poorly sanitized farm equipment. However, measures (including hygiene) can limit the importance of such alternative pathways.
Considering the numerous bibliographic references that highlight the importance of plants for planting as an important pathway, and the existence of measures that can reduce the role of the others reported pathways, host plants for planting with roots, with or without soil or growing media, are a considered as a main pathway.

Yes

Pratylenchus penetrans has been reported as a pathogen for Fragaria in several countries (e.g. United States, Canada, Costa Rica, Israel, Spain) (Anonymous, 1999; Montes et al., 2006; Qing, 2008; Jackson-Ziems, 2016; MAPA, 2019; Talavera et al., 2019; Sandoval-Ruíz et al., 2023).

In Spain, this species is among the main plant pathogenic nematodes in strawberry crops (López-Aranda, 2008; MAPA, 2019; Talavera et al., 2019; Talavera, 2021; De los Santos et al., 2022). Talavera et al. (2019) found it in 20% of the commercial strawberry plantations of Huelva with an abundance range between 3 and 94 nematodes per 100 g of soil.

The pathogenicity of P. penetrans on strawberry plants has been demonstrated under both controlled and field conditions (see references in Bélair et al., 2018). Affected plants show a marked reduction of the root system and several associated non-specific aerial symptoms (dwarfism, chlorosis, wilting, lack of vigour, smaller fruits), sometimes leading to plant death (Montes et al., 2006; MAPA, 2019).

The wounds inflicted in the root system also favors the entry of other pathogens, especially fungi (e.g. Macrophomina phaseolina, Fusarium spp., Verticillim dahliae), causing complex diseases in strawberries (McKinley y Talboys, 1979, MAPA, 2019; Talavera et al., 2021). In fact, P. penetrans is one of the main components of the black root rot (BRR) complex (together with members of the genera Fusarium, Rhizoctonia, Pythium, Cylindrocarpon and Pestalotia) (Montes et al., 2006; López-Aranda, 2008; MAPA, 2019), an important strawberry pathology that, according to some experts, would have an even greater economic impact than crown rot caused by Phytophthora cactorum (López-Aranda, 2008).

Major

No

Candidate

Its economic impact on Fragaria, both direct and indirect (in association with other pathogens), is well documented.

Candidate

Crop rotation is difficult because of the wide host range of Pratylenchus penetrans, including weeds. Pratylenchus penetrans can propagate well on many crops, sometimes without causing damage (symptomless) (aaltjesschema). Recent research indicated that with proper choice of selected cultivars of cover crops, P. penetrans can be controlled but further breeding efforts are needed. Although some cover crops can reduce the population of Pratylenchus penetrans (Taning et al., 2023). Since many weeds can also be a host, adequate weed control is important (Aaltjesschema, 2019).

Growing Tagetes spp. (e.g. Tagetes patula) can reduce the population considerably (Evenhuis et al., 2004). The authors predicted that strawberries could be grown for about 7 successive years without economic damage due to the root lesion nematode. Pudasaini et al. (2006) showed that Tagetes can reduce P. penetrans exponentially in time under marigold. The effect of marigold was persistent as no increase in P. penetrans densities over the whole soil profile was noticed after two crop cycles of host plants.

Use of clean soil: The propagation material is kept either in containers of sterilized growing medium or in soil that has been tested and found free from various nematodes (e.g. EPPO 2022).

Soil fumigation: dependent on legislation. Preplant soil fumigation does not eradicate nematodes but dramatically reduces nematode numbers. The nematodes return to their original population density (or greater) within 2 or 3 years after planting, but the absence of nematode pressure during the initial years of establishment is critical for trees to develop strong, healthy root systems (Abawi & Mai, 2014). With the progressive phase-out of chemical nematicides such as Aldicarb, Carbofuran, and 1,3-Dichloropropene, the effectiveness and sustainability of current plant-parasitic nematode management strategies remain limited (Barbosa et al., 2022).

Healthy plants: To prevent the introduction of nematode problems, new orchards should be established with trees obtained from reputable nurseries that treat their soils for nematodes (Abawi & Mai, 2014).

Candidate