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Open AccessArticle

Fungicide Treatments to Control Seed-borne Fungi of Sunflower Seeds

1
College of Horticulture and Plant Protection, Inner Mongolia Agricultural University, Hohhot 010018, China
2
Institute of Grassland Research of CAAS, Huhhot 010010, China
3
Department of Plant Pathology, Washington State University, Pullman, WA 99164, USA
*
Author to whom correspondence should be addressed.
Pathogens 2020, 9(1), 29; https://doi.org/10.3390/pathogens9010029
Received: 27 November 2019 / Revised: 22 December 2019 / Accepted: 24 December 2019 / Published: 27 December 2019
Seed-borne fungi in 69 sunflower cultivars were evaluated which comprised 52 confectionery and 17 oilseed types. Seed coats were placed on both NP-10 (Nonylphenol Ethoxylate based surfacant −10) and potato dextrose agar (PDA) media to culture fungi. The rate of contamination among the different varieties was calculated by counting seed coats with fungal colonies. The rate of contamination in the confectionary group (88%) was significantly (p ≤ 0.05) higher than in the oilseed group (71%). Of the 52 confectionery varieties, the dominant fungi recovered were Verticillium dahliae along with Alternaria spp., Fusarium spp., and Rhizopus spp., whereas the oilseed type varieties were contaminated with only V. dahliae. Molecular identification of fungal species via BLAST (Basic Alignment Search Tool) was performed on fungal sequences obtained from PCR (Polymerase Chain Reaction) analysis. The results included five Alternaria spp. that included Alternaria tenuissima, Alternaria alternata, Alternaria helianthiinficiens, Alternaria longipes, and Alternaria tamaricis, three Fusarium spp. such as Fusarium oxysporum, Fusarium incarnatum, and Fusarium proliferatum, and V. dahliae and Cladosporium cladosporioides. These were identified from pure fungal cultures recovered from seed coats. To efficiently control seed-borne fungi, four broad spectrum fungicides (carbendazim, triadimefon, caprio F-500, and flusilazole) were screened against V. dahliae isolate Gn3, which was isolated from a diseased LD 5009 sunflower plant. Flusilazole was selected based on its low half-maximal effective concentration value (EC50), 78.7 µg/mL. Seeds of diseased LD 5009 plants obtained from two different locations treated with formulated flusilazole fungicide at optimum parameters showed a significant (p ≤ 0.05) increase in seed germination and a decrease in contamination rate from 98% to less than 10%. The results affirmed that confectionery cultivars are much more susceptible to fungal contamination than oilseeds, and also that seed pretreatment is a suitable way to prevent the spread of soil- and seed-borne fungi in sunflower production. View Full-Text
Keywords: flusilazole; sunflower; seed-borne fungi; seed coat contamination; seed pretreatment flusilazole; sunflower; seed-borne fungi; seed coat contamination; seed pretreatment
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MDPI and ACS Style

Addrah, M.E.; Zhang, Y.; Zhang, J.; Liu, L.; Zhou, H.; Chen, W.; Zhao, J. Fungicide Treatments to Control Seed-borne Fungi of Sunflower Seeds. Pathogens 2020, 9, 29.

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