Application to soil of disinfectants through irrigation reduces Verticillium dahliae in the soil and verticillium wilt of olive

Abstract

The application of disinfectants through drip irrigation could be a feasible practice against verticillium wilt (Verticillium dahliae) of olive. OX‐VIRIN (activated peroxide) and OX‐AGUA AL25 (quaternary ammonium compounds) are two disinfectants that have shown efficacy against V. dahliae in irrigation water and potential for reducing the disease in young olive plants. In this work, various post‐planting application strategies incorporating OX‐VIRIN (once a month, or twice a month on alternate or successive weeks) or OX‐AGUA AL25 (once a month, or twice a month on alternate weeks) were assessed for their effect on V. dahliae in soil, disease in olive trees, and olive yield, in a 2‐year pot‐experiment under natural environmental conditions. The disinfectants were injected via metering pumps into a drip irrigation system that irrigated olive trees planted in V. dahliae‐inoculated soil. All the application strategies significantly reduced the total inoculum density in soil compared to controls with no disinfectants and noninoculated soil. The microsclerotia density was also significantly reduced in disinfested soils by 73.6–86.8%, depending on the strategy. The symptoms and infection incidence were always lower in treatments subjected to disinfestation. The treatment with OX‐AGUA AL25 applied twice a month on alternate weeks most reduced the symptoms (by 53.0%) and colonization index (by 70.8%) with respect to untreated water control. This soil disinfestation also significantly strengthened the symptom remission. Tree growth and production were negatively affected by soil inoculation (reduced by 45.6% and 88.7%, respectively), but not so by disinfectants, which even relieved the reduction in inoculated soils, especially when OX‐AGUA AL25 was applied.

The Oleic/Linoleic Acid Ratio in Olive (Olea europaea L.) Fruit Mesocarp Is Mainly Controlled by OeFAD2-2 and OeFAD2-5 Genes Together With the Different Specificity of Extraplastidial Acyltransferase Enzymes

“…The study was also extended to the 36 cultivars ( Supplementary Table 2 ) corresponding to a previously established core collection (Core-36) ( Belaj et al, 2012 ), which included 28 cultivars from the 89 selected from the WOGBC. Trees, two per accession, were cultivated in the same agroclimatic conditions at the experimental orchards of IFAPA (Alameda del Obispo, Córdoba, Spain) at 6 m × 5 m spacing, using standard culture practices ( Gómez-Gálvez et al, 2020 ). In order to obtain representative samples of the olive fruits from all parts of the olive trees, fruits were harvested by hand all around from two trees per cultivar, mixed and spliced into three different pools, that constitute three different biological replicate, for oil fatty acid analysis and mesocarp developmental studies.…”

Wild Olive Genotypes as a Valuable Source of Resistance to Defoliating Verticillium dahliae

“…Soil solarization, the application of organic amendments to the soil ( Varo-Suárez et al, 2018 ), and the use of biological control agents are sustainable and promising control strategies ( Areal and Riesgo, 2014 ; Gómez-Lama Cabanas et al, 2018 ; Azabou et al, 2020 ; Boutaj et al, 2020 ; Castro et al, 2020 ; Mulero-Aparicio et al, 2020 ). Preventive or curative chemical fungicides can only partially control the disease ( Tjamos, 1993 ; Fradin and Thomma, 2006 ; Tsror, 2011 ; Gómez-Gálvez et al, 2020 ). Biotechnological approaches such as the preventive detection of V. dahliae by using specific and highly sensitive molecular methods such as quantitative real-time PCR (qPCR), allows the identification of both healthy plant material and free-pathogen pre-planting soils.…”

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

“…In addition to the advantages mentioned above, they can be applied in a wide range of circumstances. Indeed, the application of OX-VIRIN ® and OX-AGUA AL25 ® produced a decrease in MS viability both under in vitro conditions [123,124] and in V. dahliae naturally [123] or artificially infested [127] soils. Likewise, the effectiveness of the treatments was verified in soil with plants by evaluating the VWO development.…”

“…Under field conditions, olive trees transplanted into a soil previously treated with the disinfectants effectively withstood the disease [ 128 ]. Similarly, a reduction in symptoms and disease incidence was found in olive trees transplanted into an artificially infested soil subjected to disinfestation with respect to untreated water control [ 127 ]. Moreover, the addition of these disinfectants neither affected the growth parameters (shoot weight and foliar area) nor caused phytotoxicity [ 125 , 127 ] and, surprisingly, improved the growth of the trees [ 127 ]…”