First Report of Root Rot and Wilt Caused by <i>Pythium myriotylum</i> on Hemp (<i>Cannabis sativa</i>) in the United States

McGehee, Cora S.; Apicella, Peter V.; Raudales, Rosa E.; Berkowitz, Gerald A.; Ma, Yingjun; Durocher, Shelley N.; Lubell, Jessica D.

doi:10.1094/pdis-11-18-2028-pdn

Cited by 11 publications

(9 citation statements)

References 5 publications

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“…Despite these limitations, our research indicates that isolates in soilless substrates can cause diseases on hemp significantly reducing its potential to grow. Based on this study and previous ones (Punja and Rodriguez, 2018;McGehee et al, 2019) we can also conclude that P. myriotylum is frequently found in the rhizosphere of cannabis plants grown in soilless substrates. Further research should investigate whether some soilless substrates are more or less conducive to harbor specific groups of pathogens, as we observed from our sampling.…”

Section: Discussionsupporting

confidence: 81%

“…These results suggest a diverse population of P. myriotylum within the production facility that was sampled in this project. The morphological characteristics of P. myriotylum isolates recovered from this study were similar to those of PM11 collected from hemp roots in 2019 (McGehee et al, 2019). Both isolates were recovered from the root-zone of Cannabis sativa L. plants in Connecticut, yet the environment and genetic make-up of the hosts differ.…”

Section: Discussionsupporting

confidence: 58%

“…P. myriotylum, the species recovered at the highest frequency in this study, has been previously identified as the causal agent of wilting, stunting, and chlorosis on marijuana and hemp plants grown in soilless systems (Punja and Rodriguez, 2018;McGehee et al, 2019) and G. irregulare had not been reported in hemp or marijuana before. Punja and Rodriguez (2018) found P. dissotocum at the highest frequency (70%).…”

Section: Discussionmentioning

confidence: 60%

“…Punja and Rodriguez (2018) confirmed symptoms of root rot, reduced growth, chlorosis, and wilt caused by P. aphanidermatum, P. dissotocum, P. myriotylum, F. oxysporum, and F. solani in hydroponically-grown marijuana in Canada. We recovered P. myriotylum from necrotic roots of a wilted hemp plant grown in a research greenhouse in Connecticut, USA (McGehee et al, 2019). Root rot and wilt on field-grown C. sativa L. caused by Pythium spp.…”

Section: Introductionmentioning

confidence: 99%

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Pathogenicity and Mefenoxam Sensitivity of Pythium, Globisporangium, and Fusarium Isolates From Coconut Coir and Rockwool in Marijuana (Cannabis sativa L.) Production

McGehee

Raudales

2021

Front. Agron.

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Oomycetes and fungi were recovered from coconut coir and rockwool substrates where marijuana (Cannabis sativa L. cv. Silver and Citron) plants with root rot and wilt symptoms were grown in a commercial growing facility in Connecticut. The objectives of this study were to identify the isolates collected from these substrates, determine the pathogenicity of the isolates on hemp seedlings in vitro and in vivo, and evaluate the pathogens' sensitivity to mefenoxam. Pythium and Globisporangium isolates were identified by sequencing the mitochondrially-encoded cytochrome oxidase genes (COI and COII) and Fusarium sp. with the translation elongation factor (EF-1α) region and internal transcribed spacer region (ITS4 and ITS5) genes. Three isolates were identified as Globisporangium irregulare (formerly Pythium irregulare), 21 isolates were Pythium myriotylum, and one was Fusarium oxysporum. All the isolates tested were pathogenic to hemp plants in vitro and in vivo, with disease incidence between 6.7 and 100%. Inoculated plants were smaller by 32% or more compared with the non-inoculated control. On average, hemp plants infected with Pythium myriotylum produced the lowest biomass and relative greenness values. None of the Pythium and Globisporangium isolates were resistant to mefenoxam—all were sensitive to ≥5 μg·mL−1 mefenoxam. This is the first report of G. irregulare causing root rot on marijuana and hemp plants. The results of this study provide information about the characteristics of pathogens that can be found potentially in soilless substrates in controlled environment agriculture.

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Section: Discussionsupporting

confidence: 81%

Section: Discussionsupporting

confidence: 58%

Section: Discussionmentioning

confidence: 60%

Section: Introductionmentioning

confidence: 99%

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Pathogenicity and Mefenoxam Sensitivity of Pythium, Globisporangium, and Fusarium Isolates From Coconut Coir and Rockwool in Marijuana (Cannabis sativa L.) Production

McGehee

Raudales

2021

Front. Agron.

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“…Both crown and root rots are more common in cool conditions than in hot conditions, particularly in low lying or flood-prone areas where hemp is intensively grown. Findings from field tests indicate P. aphanidermatum could infect different tissues and organs of cannabis plants, resulting in rot, wilt, and eventual collapse of the whole host plant [31][32][33][34][35][36].…”

Section: Fungal Pathogens Of Bast Fiber Cropsmentioning

confidence: 99%

Molecular Diagnostics and Pathogenesis of Fungal Pathogens on Bast Fiber Crops

et al. 2020

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Bast fibers and products derived from them are undergoing a resurgence in demand in the global market. However, fungal diseases have become an important factor limiting their yield and quality, causing devastating consequences for the production of bast fiber crops in many parts of the world. Thus, there is a high demand for effective control and prevention strategies against fungal pathogens. Having rapid, specific, sensitive, and cost-effective tests that can be used for early and accurate diagnosis of disease agents is an essential step of such strategies. The objective of this study was to review the current status of research on molecular diagnosis of fungal pathogens on bast fiber crops. Our search of PubMed identified nearly 20 genera of fungal pathogens on bast fiber crops, among which the five most common genera were Colletotrichum, Pythium, Verticillium, Fusarium, and Golovinomyces. The gene regions that have been used for molecular identifications of these fungi include internal transcribed spacer (ITS), translation elongation factor 1-α (EF-1α), ß-tubulin, calmodulin (CAL), histone subunit 3 (H3), glyceraldehydes-3-phosphate dehydrogenase (GAPDH), etc. We summarize the molecular assays that have been used to identify these fungi and discuss potential areas of future development for fast, specific, and accurate diagnosis of fungal pathogens on bast fiber crops.Pathogens 2020, 9, 223 2 of 19 and control. However, conventional protocols based on morphological and physiological methods are time-consuming, require significant experience, and may not be sensitive and specific for individual pathogens [3]. Moreover, many fungal pathogens can remain latent in "sub-infection" stages with no obvious symptoms and/or in low numbers, making them difficult to detect, and causing confusion with their roles in diseases. These issues can contribute to delayed or wrong control measures.During the last three decades, to overcome these problems and minimize crop losses caused by fungal diseases, a diversity of DNA molecule-based tools has been developed for the detection and identification of fungal pathogens. These techniques include conventional polymerase chain reaction (PCR) [4], quantitative PCR (qPCR) [5,6], immunocapture-PCR (IC-PCR) [7,8], droplet digital PCR (dd-PCR) [9], loop-mediated isothermal amplification (LAMP) [10], multiplex tandem PCR [11], fluorescence in situ hybridization (FISH) [12], and DNA microarrays [3]. These methods are typically faster and more accurate than those based on colony morphology, microscopic features, and/or physiological/biochemical characters of pure fungal cultures. Indeed, methods targeting DNA sequences have been applied to detect pathogens during crops' growth, harvest and postharvest processing stages [13]. Moreover, they have also enabled a deeper understanding of microbial populations and communities associated with crops, especially the microorganisms that are difficult or impossible to cultivate in the lab. Together, technological advances and developments in DNA molecu...

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The impact of climate change in the spread of Pythium myriotylum in ginger: a critical review

Yosilia,

Afandi,

Lindiana

et al. 2023

E3S Web Conf.

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Climate change is a growing concern due to its potential impact on biotic stressors, particularly fungal infections, such as Pythium myriotylum, which causes significant damage to ginger plants. Among the several yield-reducing fungal diseases targeting ginger, Pythium myriotylum is known to cause significant damage through rhizome rot and damping off. Scientific studies have explored the survival and spread of P. myriotylum in gingers and other crops that are thought to be caused by climate change. Oospores, the primary inoculum source, are crucial for the P. myriotylum's life cycle and disease progression. To mitigate the effects of P. myriotylum in ginger, adaptation techniques such as crop rotation, pesticide use, and breeding of resistant varieties can be developed. However, understanding the current spread of P. myriotylum and its limitations is crucial for future research. This review discusses the current status of P. myriotylum's importance in ginger, the effects of climatic variables on its life cycle, survival, and spread, adaptation strategies, and the effects of climate change on it. It also identifies significant knowledge gaps for future research.

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First Report of Root Rot and Wilt Caused by Pythium myriotylum on Hemp (Cannabis sativa) in the United States

Cited by 11 publications

References 5 publications

Pathogenicity and Mefenoxam Sensitivity of Pythium, Globisporangium, and Fusarium Isolates From Coconut Coir and Rockwool in Marijuana (Cannabis sativa L.) Production

Pathogenicity and Mefenoxam Sensitivity of Pythium, Globisporangium, and Fusarium Isolates From Coconut Coir and Rockwool in Marijuana (Cannabis sativa L.) Production

Molecular Diagnostics and Pathogenesis of Fungal Pathogens on Bast Fiber Crops

The impact of climate change in the spread of Pythium myriotylum in ginger: a critical review

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