Abstract
Use of seed-applied fungicides has become commonplace in the United States soybean production systems. Although fungicides have the potential to protect seed/seedlings from critical early stage diseases such as damping-off and root/stem rots, results from previous studies are not consistent in terms of seed-applied fungicide’s ability to mitigate yield losses. In the current study, the relationship between estimated soybean production losses due to seedling diseases and estimated seed-applied fungicide use was investigated using annual data from 28 soybean growing states in the U.S. over the period of 2006 to 2014. National, regional (northern and southern U.S.), state, and temporal scale trends were explored using mixed effects version of the regression analysis. Mixed modeling allowed computing generalized R2 values for conditional (R2GLMM(c); contains fixed and random effects) and marginal (R2GLMM(m); contains only fixed effects) models. Similar analyses were conducted to investigate how soybean production was related to fungicide use. National and regional scale modeling revealed that R2GLMM(c) values were significantly larger compared to R2GLMM(m) values, meaning fungicide use had limited utility in explaining the national/regional scale variation of yield loss and production. The state scale analysis revealed the usefulness of seed-applied fungicides to mitigate seedling diseases-associated soybean yield losses in Illinois, Indiana, North Carolina, and Ohio. Further, fungicide use positively influenced the soybean production and yield in Illinois and South Dakota. Taken together, use of seed-applied fungicide did not appear to be beneficial to many of the states. Our findings corroborate the observations made by a number of scientists through field scale seed-applied fungicide trials across the U.S and reiterate the importance of need base-use of seed-applied fungicides rather than being a routine practice in soybean production systems.
Highlights
Soybean [Glycine max (L.) Merr.] is among the most economically important crops in the United States, presently the world’s largest soybean producer (United States Department of Agriculture, World Agricultural Production Report 2019)
Over the past two decades the cost of soybean seed has increased as a result of the increasing costs associated with herbicide trait technologies and the technology fees associated with those herbicide traits
Seed-applied fungicides serve as a method to reduce overall production costs by reducing the likelihood of a replant situation which increases overall soybean production costs if and when stand failures result in the need for purchasing additional seed and the subsequent costs associated with planting [32, 42, 44]
Summary
Between 1996 and 2016, the estimated total economic losses due to soybean diseases in the U.S was $95 billion [4]. Even though an array of soilborne pathogens can cause soybean seedling and root diseases, the major ones include species of Fusarium and Rhizoctonia solani from the kingdom Fungi and the oomycetes Pythium and Phytophthora from the kingdom Stramenopila [5]. Seed-associated organisms that generally result from the environment encountered during the prior season, but more broadly considered to be the result of multiple species of Phomopsis can cause seedling disease-associated issues by reducing germination and producing poor stands. Poor plant and poor stand establishment are the major causes behind yield losses due to seedling diseases in soybean [6]. The organisms that cause seedling diseases are considered a complex as it is oftentimes difficult to determine which organism(s) are involved
Published Version (Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have