By N. K. Osterbauer and C. M. Ocamb
Cause Soilborne microorganisms Pythium dissotocum, P. myriotylum, Rhizoctonia solani, Fusarium oxysporum, F. solani and other Fusarium spp. All can survive on plant debris in soil as durable spores; all have a broad host range. Fusarium solani can cause more severe symptoms than F. oxysporum and the latter fungus can be a problem on vegetative cuttings.
Symptoms Aboveground portions of affected plants wilt, especially during the flowering stage, and may die; stunting may occur. Foliage can take on a yellowish coloration and stems can turn brown, including the inner pith tissues. Flower buds can be infected and take on a brown, rotten appearance. In early stages of the disease, roots appear discolored. As the disease progresses, lateral roots are absent or decayed and crown tissues may be rotted and appear brown.
Cultural control
- Sanitation practices, such as using clean pots and sterile media, are recommended.
- Avoid high levels of organic matter in planting medium.
- Cleaning planting tools and equipment can help to minimize disease.
- Do not re-use potting media from diseased plants.
References Punja, Z.K. 2018. Flower and foliage-infecting pathogens of marijuana (Cannabis sativa L.) plants. Can J Plant Pathol. 40:514-527. DOI:10.1080/07060661.2018.1535467.
Punja, Z.K. 2020. Epidemiology of Fusarium oxysporum causing root and crown rot of cannabis (Cannabis sativa L., marijuana) plants in commercial greenhouse production. Can. J Plant Pathol. DOI:10.1080/07060661.2020.1788165.
Punja, Z.K., Cameron, S., and Chen, S. 2018. Root and crown rot pathogens causing wilt symptoms on field-grown marijuana (Cannabis sativa L.) plants. Can. J Plant Pathol.: DOI: 10.1080/07060661.2018.1535470
Punja, Z.K., Collyer, D., Scott, C., Lung, S., Holmes, J., and Sutton, D. 2019. Pathogens and molds affecting production and quality of Cannabis sativa L. Frontiers Pl. Sci. 10:1120.