Location: Integrated Cropping Systems ResearchTitle: Fungicidal seed coatings exert minor effects on arbuscular mycorrhizal fungi and plant nutrient content Author
|Cameron, Jesse - Former Ars Employee|
|Lehman, R - Michael|
|Sexton, Peter - South Dakota State University|
|Taheri, Wendy - Former Ars Employee|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2017
Publication Date: 5/5/2017
Citation: Cameron, J.C., Lehman, R.M., Sexton, P., Osborne, S.L., Taheri, W.I. 2017. Fungicidal seed coatings exert minor effects on arbuscular mycorrhizal fungi and plant nutrient content. Agronomy Journal. 109:1005-1012.
Interpretive Summary: We evaluated anti-fungal seed coatings on corn, soybean and oat for their potential to affect colonization of their roots by generally-beneficial arbuscular mycorrhizal (AM) fungi as well as plant nutrient status. Our experiment utilized several varieties (soybean, oat) or hybrids (corn) to enable the effect of plant genotype on AM fungal colonization to be evaluated simultaneously. We found that commonly-used, seed-applied fungicides (applied at labeled rate) with multiple ingredients, and multiple modes of action, had minimal effect on AM fungal colonization and nutrient status of corn, soybean, and oat. In contrast, differences in plant genotype (variety or hybrid) commonly resulted in changes AM fungal root colonization and plant nutrient content, confirming other studies in this regard. We conclude that the fungicidal seed coatings tested were unlikely to produce an undesired negative effect on AM fungi, a class of generally-beneficial obligate plant symbionts. Additional testing would be required to support robust recommendations for all combinations of crops and fungicides.
Technical Abstract: Aims: Determine if contemporary, seed-applied fungicidal formulations inhibit colonization of plant roots by arbuscular mycorrhizal (AM) fungi, plant development, or plant nutrient content during early vegetative stages of several commodity crops. Methods: We evaluated seed-applied commercial fungicides labeled for use with corn (Zea mays L.), soybean (Glycine max (L) Merr), and oat (Avena sativa L.). Three corn hybrids, three soybean varieties, and two oat varieties were raised in the greenhouse for ~6 weeks. There were four treatments for each hybrid/variety that included a no fungicide control and three commercial fungicides containing mixtures of locally-systemic, xylem mobile, and contact active ingredients. Plant development (growth stage, weight), plant nutrient concentration, and percent of root colonized by AM fungi (mixed species) were measured. Results: Fungicidal seed coatings did not significantly (0.05 alpha) reduce AM root colonization or P content of any plant compared to the control. Plant variety affected (p<0.05) AM root colonization for corn, soybean, and oat. There were significant differences among fungicides in AM fungal colonization and plant nutrients for all three plants. Conclusions: Seed applied fungicides have minimal effect on AM colonization and nutrient status of corn, soybean, and oat which were more affected by host genotype.