Penicillium pinophilum has the potential to reduce damping-off caused by Rhizoctonia solani in sugar beet

Authors: HAQUE, M - North Dakota State University; Lakshman, Dilip; AIMING, QI - University Of Hertfordshire; KHAN, M - North Dakota State University

Submitted to: Sugar Tech
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2021
Publication Date: 2/26/2021
Citation: Haque, M.E., Lakshman, D.K., Aiming, Q., Khan, M.F. 2021. Penicillium pinophilum has the potential to reduce damping-off caused by Rhizoctonia solani in sugar beet. Sugar Tech. https://doi.org/10.1007/s12355-021-00958-8.
DOI: https://doi.org/10.1007/s12355-021-00958-8

Interpretive Summary: Rhizoctonia solani causes pre-emergence and post-emergence damping-off, as well as crown and root rot of sugar beet (Beta vulgaris L.), which significantly affect the yield returns in the USA and Europe. The pathogen survives in the soil as sclerotia or melanized mycelium. Traditionally, chemical strategies such as seed treatment (penthiopyrad), and in-furrow application of fungicides such as azoxystrobin at planting provide effective control of the disease in the field. However, because of the environmental concerns, carryover of chemical residues in the corm, and development of resistance to fungicides by Rhizoctonia pathogens, alternative disease management studies such as biocontrol is increasingly sought by the farmers and consumers. In this investigation, we have discovered and evaluated the suppressive effect of Penicillium pinophilum to biocontrol Rhizoctonia damping-off of sugarbeet both in the laboratory and greenhouse. It was concluded that P. pinophilum has the potential to reduce damping-off caused by R. solani, and its mitigation mechanisms need further studies. This information will be useful to scientists developing additional control measures for this important plant pathogen.

Technical Abstract: Rhizoctonia solani is an economically important pathogen of sugar beet (Beta vulgaris L.) causing seedling damping-off, and root and crown rot. Cultural practices, partially resistant cultivars, and fungicides are among the methods most used to manage R. solani. Penicillium pinophilum, a potential bio-control agent for Rhizoctonia damping-off, was isolated from sugar beet. Our objective was to evaluate the bio-control potential of Penicillium pinophilum against R. solani AG 2-2 under laboratory and greenhouse conditions. In vitro co-culture of both fungi showed that R. solani growth was inhibited by P. pinophilum. A greenhouse inoculation study was done using sclerotia of R. solani and a conidia suspension of P. pinophilum to evaluate the response of a Rhizoctonia susceptible cultivar. Treatments included R. solani sclerotia, P. pinophilum conidia suspension, a combination of R. solani sclerotia with P. pinophilum conidia suspension, and a mock inoculation with water (control). One 2-cm deep furrow was made in the middle of peat filled trays into which 10 seeds were planted. Each treatment was applied adjacent to each seed and covered with peat. There were four replicates per treatment arranged in a completely randomized design. The sole sclerotia treatment caused 75% damping-off and severe root rot on surviving plants, while the combination of sclerotia with Penicillium conidia suspension reduced damping-off by 75%. No damping-off incidences were observed with the Penicillium conidia suspension or the mock-inoculated control. It was concluded that P. pinophilum has the potential to reduce damping-off caused by R. solani and its mitigation mechanisms need further studies.