Survival time of Phytophthora species in peat-reduced growing media under different storage conditions

In horticulture, the ecologically urgent switch to peat-free or peat-reduced growing media is a complex and challenging issue. Substrates should not only give the optimal chemical conditions for growing plant cultures but also be safe from soil-borne pathogens. One of the most destructive group of...

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Main Authors: Fabricio Fabián Soliz Santander, Janett Riebesehl
Format: Article
Language:deu
Published: Julius Kühn-Institut 2025-08-01
Series:Journal für Kulturpflanzen
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Online Access:https://ojs.openagrar.de/index.php/Kulturpflanzenjournal/article/view/17802
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author Fabricio Fabián Soliz Santander
Janett Riebesehl
author_facet Fabricio Fabián Soliz Santander
Janett Riebesehl
author_sort Fabricio Fabián Soliz Santander
collection DOAJ
description In horticulture, the ecologically urgent switch to peat-free or peat-reduced growing media is a complex and challenging issue. Substrates should not only give the optimal chemical conditions for growing plant cultures but also be safe from soil-borne pathogens. One of the most destructive group of pathogens is the oomycete genus of Phytophthora, which can pose significant risks to plant nurseries. Commonly, these oomycetes remain latent in substrates until the proper condi­tions come to infect the plants. So far, little research has been done on the survival time of this oomycete genus in poten­tially new culture media. The aim of this study was to determine the survival time of Phytophthora spp. in peat-reduced substrates suitable for horticultural crops. These include combinations of coir pith, humus, compost, wood fibre, fibre nettle, digestate and peat. Four pathogenic species were selected: P. pseudocryptogea, P. lateralis, P. cactorum and P. nicotianae. These are potential pathogens of three important horticultural crops: Lawson cypress (Chamaecyparis lawsoniana), garden strawberry (Fragaria × ananassa) and Persian cyclamen (Cyclamen persicum). The substrate mixtures were disinfected, inoculated artificially with three different isolates of one Phytophthora species and incubated under defined conditions (4 °C or 15 °C). To check the survival time, a baiting test procedure for the isolation of oomycetes with Rhododendron leaves was carried out at reg­ular intervals in order to reisolate living and active oomycetes. Results showed a significant suppression effect from a mixture of peat and digestate (fermentation product) against P. lat­eralis and P. pseudocryptogea at both 4 °C and 15 °C. While different substrate mixtures had no influence on the survival time of P. nicotianae, a significantly higher survival time was exhibited at 15 °C temperature compared to 4 °C. No effects of the substrates or the temperature on P. cactorum was derived from the statistical analysis under the experiment conditions. These results can be used to glean recommendations for the storage time of peat-reduced growing media at 4 °C or 15 °C to develop management practices on horticultural substrates at the level of nurseries or substrate manufacturers to mini­mize the risk of the spread of oomycetes.
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record_format Article
series Journal für Kulturpflanzen
spelling doaj-art-dc320c06ac094c4f9c4752913d6bdd7c2025-08-22T11:42:46ZdeuJulius Kühn-InstitutJournal für Kulturpflanzen1867-09111867-09382025-08-01770110.5073/JfK.2025.01.14Survival time of Phytophthora species in peat-reduced growing media under different storage conditionsFabricio Fabián Soliz Santander0https://orcid.org/0000-0001-6136-9686Janett Riebesehl1https://orcid.org/0000-0002-0160-4813Julius Kühn Institute (JKI) – Federal Research Centre for Cultivated Plants, Institute for Plant Protection in Horticulture and Urban Green, Braunschweig, Germany.Julius Kühn Institute (JKI) – Federal Research Centre for Cultivated Plants, Institute for Plant Protection in Horticulture and Urban Green, Braunschweig, Germany. In horticulture, the ecologically urgent switch to peat-free or peat-reduced growing media is a complex and challenging issue. Substrates should not only give the optimal chemical conditions for growing plant cultures but also be safe from soil-borne pathogens. One of the most destructive group of pathogens is the oomycete genus of Phytophthora, which can pose significant risks to plant nurseries. Commonly, these oomycetes remain latent in substrates until the proper condi­tions come to infect the plants. So far, little research has been done on the survival time of this oomycete genus in poten­tially new culture media. The aim of this study was to determine the survival time of Phytophthora spp. in peat-reduced substrates suitable for horticultural crops. These include combinations of coir pith, humus, compost, wood fibre, fibre nettle, digestate and peat. Four pathogenic species were selected: P. pseudocryptogea, P. lateralis, P. cactorum and P. nicotianae. These are potential pathogens of three important horticultural crops: Lawson cypress (Chamaecyparis lawsoniana), garden strawberry (Fragaria × ananassa) and Persian cyclamen (Cyclamen persicum). The substrate mixtures were disinfected, inoculated artificially with three different isolates of one Phytophthora species and incubated under defined conditions (4 °C or 15 °C). To check the survival time, a baiting test procedure for the isolation of oomycetes with Rhododendron leaves was carried out at reg­ular intervals in order to reisolate living and active oomycetes. Results showed a significant suppression effect from a mixture of peat and digestate (fermentation product) against P. lat­eralis and P. pseudocryptogea at both 4 °C and 15 °C. While different substrate mixtures had no influence on the survival time of P. nicotianae, a significantly higher survival time was exhibited at 15 °C temperature compared to 4 °C. No effects of the substrates or the temperature on P. cactorum was derived from the statistical analysis under the experiment conditions. These results can be used to glean recommendations for the storage time of peat-reduced growing media at 4 °C or 15 °C to develop management practices on horticultural substrates at the level of nurseries or substrate manufacturers to mini­mize the risk of the spread of oomycetes. https://ojs.openagrar.de/index.php/Kulturpflanzenjournal/article/view/17802horticulture substratepeat reductionsoil borne pathogensplant diseasesOomycotaPeronosporales
spellingShingle Fabricio Fabián Soliz Santander
Janett Riebesehl
Survival time of Phytophthora species in peat-reduced growing media under different storage conditions
Journal für Kulturpflanzen
horticulture substrate
peat reduction
soil borne pathogens
plant diseases
Oomycota
Peronosporales
title Survival time of Phytophthora species in peat-reduced growing media under different storage conditions
title_full Survival time of Phytophthora species in peat-reduced growing media under different storage conditions
title_fullStr Survival time of Phytophthora species in peat-reduced growing media under different storage conditions
title_full_unstemmed Survival time of Phytophthora species in peat-reduced growing media under different storage conditions
title_short Survival time of Phytophthora species in peat-reduced growing media under different storage conditions
title_sort survival time of phytophthora species in peat reduced growing media under different storage conditions
topic horticulture substrate
peat reduction
soil borne pathogens
plant diseases
Oomycota
Peronosporales
url https://ojs.openagrar.de/index.php/Kulturpflanzenjournal/article/view/17802
work_keys_str_mv AT fabriciofabiansolizsantander survivaltimeofphytophthoraspeciesinpeatreducedgrowingmediaunderdifferentstorageconditions
AT janettriebesehl survivaltimeofphytophthoraspeciesinpeatreducedgrowingmediaunderdifferentstorageconditions