Effect of Seeding Rate and Seed Treatment Fungicides on Agronomic Performance, Fusarium Head Blight Symptoms, and DON Accumulation in Two Winter Wheats

Abstract

Fusarium head blight (FHB), caused by Fusarium graminearum, is an important disease of wheat (Triticum aestivum). FHB reduces yield and quality, and the pathogen produces several toxins in the grain, the most important being deoxynivalenol (DON). In North America, the foliar fungicide tebuconazole is used to reduce FHB symptoms and DON accumulation. Because of the narrow window required for its application, uniform flowering of wheat is important. The objective of this study was to investigate the influence of variety, seeding rate, and seed treatment fungicides on the flowering period of winter wheat and their effect on FHB symptoms and DON accumulation. The seed of two winter wheat varieties (Pioneer 25W60 and Pioneer 25R57) was treated with Dividend XL (difeconazole+metalaxyl), Vitaflo 280 (thiram+carbathiin), Raxil (tebuconazole), and Baytan 30 (triadimenol) and planted at 320, 480, and 640 seeds per m2 for each treatment at Ridgetown, ON, Canada in 2000 and 2001. The plots were sprayed with tebuconazole at 50% anthesis and inoculated with F. graminearum 3 days later. Increased seeding rate increased the number of emerged plants, tillers, spikes per m2, and yield. All seed treatments, compared to nontreated controls, increased plant emergence and number of spikes per m2, and all except tebuconazole increased tillering and yield. Increased seeding rate decreased the length of flowering period. As flowering period increased, FHB index and DON level decreased, suggesting that greater infection was linked to more uniform flowering.

Effectiveness of fungicide seed treatments for preventing seed-to-seedling transmission of Fusarium graminearum under controlled-environment conditions

“…Some other studies have also reported negative effects of some fungicide seed treatments on crop performance. Schaafsma and Tamburic-Ilincic (2005) found that in the field Raxil 250 FL resulted in fewer plants and a lower density of tillers and spikes than other treatments, and was similar to the untreated infected control. Martin and Matters (2002) also reported that the Raxil-Thiram treatment had a lower yield than the untreated infected control, but that there was no difference in kernel weight among treatments.…”

“…Although there have been previous controlled-environment and field studies on the effectiveness of fungicide seed treatments against Fusarium seed infection of cereal crops, results have not been consistent (Klein and Burgess 1987;Gilbert and Tekauz 1995;Schaafsma et al 2001;Schaafsma and Tamburic-Ilincic 2005). Furthermore, most of the studies on Fusarium-infected seed have concentrated on F. graminearum, whereas in the western prairies there are usually other Fusarium species and fungal species present in seed from FHB-affected wheat crops.…”

Winter Wheat Yields Are Increased by Seed Treatment and Fall‐Applied Fungicide

“…Given the potential role of seed treatments, there have been relatively few studies on seed treatment and its impact on stand establishment, winter survival and crop yield, especially in western Canada. In Ontario, Schaafsma and Tamburic-Ilincic (2005) reported that a fungicide seed treatment increased fall seedling emergence and the number of tillers the following spring. Most products also increased yield in the presence of Fusarium head blight caused by Fusarium graminearum, but seed and soil-borne disease levels and causal agents were not assessed.…”

“…Crop responses to seed treatments can extend beyond mitigation of pathogens or insect pests. Studies of winter wheat report improved plant stands, yield components, and grain yield where only a fungicide seed treatment such as tebuconazole was applied (Schaafsma and Tamburic-Ilincic, 2005). A Canadian study on canola reported improved seedling emergence and grain yield with dual fungicide/insecticide seed treatments (Hwang et al, 2015).…”

The role of genetics, growth habit, and cultural practices in the mitigation of Fusarium head blight

“…to roots and coleoptiles of seedlings in a trial carried out under greenhouse conditions (Jørgensen et al 2012). Some fungicidal STs increased winter wheat plant stands and grain yield; however, the effectiveness of the same STs in managing FHB were inconsistent (Schaafsma and Tamburic-Ilincic 2005). May et al (2010) reported that fungicidal ST did not always improve seedling emergence and had no significant effect on grain yield.…”