Long-Distance Spread of Verticillium dahliae Through Rivers and Irrigation Systems

Abstract

Verticillium dahliae Kleb. is a soilborne pathogen causing Verticillium wilt disease on several hosts. The pathogen survival structure (i.e., microsclerotia) can be efficiently spread by different dispersal methods. In the present study, the medium to long dispersal spread of the pathogen through rivers and irrigation canals was investigated. Samples of sediments (n = 29) were gathered from eight Lebanese rivers and three regional irrigation canals, in addition to samples of soil particles and plant residues (n = 14) from irrigation filters in commercial orchards. Specific conventional and real-time nested polymerase chain reaction assays detected the pathogen in six rivers—Al Kabir, Al Bared, Litani, Al Awali, Ostwan, and Litani South—and in all sampled canals—Ostwan, Al Bared, and Litani Canal 900. Starting DNA quantities ranged from 0.2 pg to 21.318 ng and an inoculum density, determined by a traditional plating method, varied between nondetectable and 0.2 microsclerotia/g. Viable V. dahliae microsclerotia were also found in residues collected from mesh-type irrigation filters of five commercial orchards. This study confirms that water is an important inoculum source of V. dahliae, being involved in the efficient spread of microsclerotia in Lebanese agricultural areas.

Potential inoculum sources of Fusarium species involved in asparagus decline syndrome and evaluation of soil disinfestation methods by qPCR protocols

“…This result shows irrigation water to be another source of inoculum of pathogenic Fusarium species. In accordance with this result, rivers and irrigation systems have previously been identified as potential sources of inoculum for pathogenic fungi, 20,29 including Fusarium species 30,31 . In this scenario, monitoring for pathogenic Fusarium species in pre‐planting soil, starting plant material and irrigation water prior to the establishment of an asparagus crop is desirable to prevent ADS and replanting problems.…”

Verticillium Wilt of Olive and Its Control: What Did We Learn during the Last Decade?

“…It is well known that the natural infective propagules of V. dahliae (microsclerotia, MS) can endure in soil or plant debris for prolonged periods of time. This dormant structures can be spread by rain, irrigation water, human and animal activities, and agricultural tools and machines, distributing the pathogen to distant areas from the original inoculum source [48]. The infection process, and hence the parasitic phase, begins when MS germinate upon stimulation by host root exudates [26].…”

“…As discussed above, irrigation water is a demonstrated dispersion source of V. dahliae infective propagules, contributing to increases VWO disease incidence and severity in some areas. Therefore, avoiding the spread of V. dahliae by irrigation systems must be a key measure within integrated disease management frameworks [48]. The use of sand filters failed to prevent the spread of V. dahliae through the drip-irrigation systems of olive orchards [122].…”

Screening of pepino (Solanum muricatum) and wild relatives against four major tomato diseases threatening its expansion in the Mediterranean region

“…This pathogenic fungus infects roots and then invades the xylem (Hu et al, 2019), causing in tomato and eggplant symptoms of vascular discoloration, wilting and yellow‐bronze leaf spots, with reduction of growth, yield and fruit quality, and eventually plant death (Karagiannidis, Bletsos, & Stavropoulos, 2002). The pathogen spreads especially by irrigation and infested seeds and locally from field to field through crop management practices (Baroudy et al, 2018; Carroll, Carter, Goodhue, Lawell, & Subbarao, 2018).…”