**Conflict of interest**

water is collected from the same infested source [75]. Also, intensive irrigation is conducive to high nematode population levels, due to its effect on soil texture remodeling, altering abiotic conditions as aeration and particle arrangement creating new niches for protection [76]. Nematode locomotion depends on water, as studied for the J2 of *Meloidogyne incognita,* which could not travel against the water flow, limiting itself to resist the flow, trying to remain static. In sand substrate tests, when water percolated, the nematode moved with the water flow,

Nematodes are already plant parasites *per se* but can also act as vectors for viruses as *Xiphinema index* (and other species) capable of transmitting *Grapevine fanleaf virus* into grapes [78]. Two nematode orders are known as vectors of plant viruses, Dorylaimida and Triplonchida [79]. For these nematode vectors, and several other species, soil is not required to be saturated, if humidity is kept at "normal levels" the parasite can survive and still act as a vector even 4 years in the absence of its hosts [80]. Also, *X. index* can be disseminated by contaminated irrigation water [81]. In some cases, these parasites are highly resistant to dehydration, in a survival strategy termed anhydrobiosis. Anhydrobiosis has been observed in many nematodes, such as among *Pratylenchus* (the lesion nematodes), one of the most important plant

Differences among irrigation methods have not been very well explored for this group of plant pathogens. However, taking into consideration the effect of water flow and irrigation on the nematode's movement and displacement, drip irrigation could result in lesser dispersal

The response of plant pathogens (fungi, oomycetes, bacteria, nematodes, viruses) to the range of irrigations methods and management configurations varies widely and must be addressed for each particular plant-pathogen system (**Figure 1**). Among furrow, overhead sprinkler, microsprinkler, and drip irrigation, there are a variety of management choices that may strongly affect propagule dispersion, induction of germination, biofilm formation, penetration and survival of each specific group of pathogens. For the oomycetes and bacteria associated to aerial plant organs, due to their strong dependency on free water and high humidity, drip irrigation might be the appropriate choice. Among the true fungi, the effects of the irrigation system and management differ, and species of dry and wet spores respond distinctly to each individual method. In some groups, such as the Erysiphales, free water may hamper disease progress. Nematodes and oomycetes need free water in the soil to be actively distributed in the crop. Viruses, accompanying their vectors, can be controlled by sprinkle irrigation water, which disrupts the contact of the insect with the plant. The knowledge of the causal agent and of the disease epidemiological components is essential when deciding the type of irrigation, frequency and water volume to be applied to manage one particular plant disease and is key to achieve good yields and high

resulting in the distribution of the nematode along irrigated areas [77].

pathogenic nematode genera [82].

**4. Conclusion**

134 Irrigation in Agroecosystems

product quality.

and consequently, less infected plants in the fields.

The authors state no conflict of interest.
