Apple nursery trees and irrigation water as potential external inoculum sources of apple replant disease in South Africa

Moein, S.; Mazzola, Mark; Ntushelo, Nombasa; McLeod, A.

doi:10.1007/s10658-018-01631-9

Cited by 18 publications

(10 citation statements)

References 45 publications

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“…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.…”

Section: Discussionmentioning

confidence: 69%

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

Lastra

Marín-Guirao

López‐Moreno

et al. 2021

Pest Management Science

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BACKGROUND Asparagus decline syndrome (ADS), one of the most important diseases affecting asparagus crops, causes important yield losses worldwide. Fusarium proliferatum, F. oxysporum and F. redolens are among the main species associated with ADS. To explore their potential inoculum sources and the effectiveness of soil disinfestation practices for ADS management, molecular methods based on a quantitative real‐time polymerase chain reaction (qPCR) were developed. qPCR‐based molecular tools demonstrated advantages in the sensitive and specific detection and quantification of fungal pathogens in comparison with less‐accurate and time‐consuming traditional culture methods. RESULTS F. proliferatum, F. oxysporum and F. redolens could be specifically detected and accurately quantified in asparagus plants, soil and irrigation water collected from asparagus fields with ADS symptoms by means of the designed TaqMan qPCR protocols. Furthermore, these molecular tools were successfully applied for evaluation of the efficacy of diverse soil disinfestation treatments. Chemical fumigation with dazomet and biosolarization with pellets of Brassica carinata contributed to a significant reduction in the inoculum densities of the three Fusarium species in treated soils, which was correlated with production increases. CONCLUSIONS The capability to accurately detect and quantify the main Fusarium species involved in ADS in plants, soil and water samples by means of qPCR will allow identification of high‐risk fields that can be avoided or managed to reduce yield losses. Quantification of pathogen densities in the soil may also provide essential insights into the effectiveness of soil disinfestation methods for ADS management. © 2021 Society of Chemical Industry.

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Section: Discussionmentioning

confidence: 69%

“…Nursery plants have been shown to be another source of inoculum because they are proven carriers of pathogenic Fusarium species 11,19 . Irrigation water has also been postulated as an external inoculum source for replanting diseases in other crops such as apple 20 …”

Section: Introductionmentioning

confidence: 99%

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

Lastra

Marín-Guirao

López‐Moreno

et al. 2021

Pest Management Science

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“…vexans infection on apple trees, particularly in orchards with a high planting density [45]. In addition, Moein et al [46] indicated that the use of higher irrigation regimes was likely the cause of the greater disease severity on inoculated apple seedlings with either P. ultimum, P. irregulare, P. sylvaticum, Pp. vexans, or Phytophthora cactorum.…”

Section: Discussionmentioning

confidence: 99%

Phytopythium vexans Associated with Apple and Pear Decline in the Saïss Plain of Morocco

et al. 2021

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An extensive survey conducted in the Saïss plain of Morocco during the 2017–2018 growing season revealed that 35 out of 50 apple and pear orchards were infested with a pathogen that causes the decline disease. Morphological and phylogenetic tree analyses using the cox II gene allowed us to identify the pathogen as Phytopythium vexans. Interestingly, no Phytophthora and Pythium species were isolated. The occurrence and prevalence of the disease varied between locations; the most infested locations were Meknes (100%), Imouzzer (83%), and Sefrou (80%). To fulfill Koch’s postulate, a greenhouse pathogenicity test was performed on the stem and collar of one-year-old healthy seedlings of apple rootstock M115. Symptoms similar to those observed in the field were reproduced in less than 4 months post-inoculation with root rot disease severity ranging from 70 to 100%. The survey results evidenced that apple rootstocks, soil type, and irrigation procedure may contribute significantly to the occurrence of the disease. The disease was most prevalent in drip water irrigation and sandy-clay soil on wild apple rootstock. Accordingly, a rational drip advanced watering system and good sanitation practices could eliminate water stagnation and help prevent the onset of this disease. It was concluded that Pp. vexans occurrence may be strongly influenced by irrigation mode and type of soil. Therefore, the obtained findings of this study could help to better understand the recurrence of this disease and to develop a reliable integrated strategy for its management.

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“…The genus Pratylenchus was only detected in two tree nurseries. It has been frequently reported in association with ARD [14,29,[49][50][51], with a damage thresholds of 50 Pratylenchus per 100 mL soil [52]. However, in other studies the reduction of Pratylenchus by nematicides did not improve tree growth in ARD affected orchards [32], or was hardly correlated with the gain in plant growth (R 2 = 0.186) [53], or ARD symptoms were observed despite reduction of Pratylenchus by soil treatment [30,52].…”

Section: Discussionmentioning

confidence: 99%

Alleviation of Nematode-Mediated Apple Replant Disease by Pre-Cultivation of Tagetes

et al. 2021

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Apple replant disease (ARD) is a severe problem in orchards and tree nurseries caused by yet unknown soil biota that accumulate over replanting cycles. This study tested the contribution of nematodes to ARD, and cultivation of Tagetes as a control option. In a pot experiment, Tagetes patula or Tagetes tenuifolia were grown in ARD soil, incorporated or removed. Nematodes extracted from untreated ARD soil and washed on 20-µm sieves induced ARD symptoms when inoculated to apple plantlets growing in a sterile substrate. In contrast, nematodes from Tagetes treated ARD soil did not reduce root growth compared to uninoculated plants, irrespective of Tagetes species and incorporation. In plots of five apple tree nurseries or orchards, either Tagetes or grass was grown on ARD soil. Nematodes extracted from the grass plots and inoculated to apple plantlets significantly reduced plant growth compared to nematodes from Tagetes plots for all five farms. Apple rootstocks showed overall a significantly higher increase in shoot base diameter when grown on Tagetes-treated plots compared to grass plots, while this effect differed among farms. Plant-parasitic nematodes were too low in abundance to explain plant damage. In conclusion, Tagetes alleviated ARD by changing the nematode community in soil.

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Apple nursery trees and irrigation water as potential external inoculum sources of apple replant disease in South Africa

Cited by 18 publications

References 45 publications

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

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

Phytopythium vexans Associated with Apple and Pear Decline in the Saïss Plain of Morocco

Alleviation of Nematode-Mediated Apple Replant Disease by Pre-Cultivation of Tagetes

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