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Planting date and seeding rate affect the microclimate within a crop field. They can influence lepidopteran insect infestation and fungal infections and are an important part of crop management strategy. Altering planting date and seeding rate can also influence yield and quality of silage corn (Zea mays L.). Field research was conducted to identify optimum planting time and seeding rate to minimize insect feeding, ear rot infections, and mycotoxin accumulation in silage corn without compromising yield and quality. Replicated field trials were conducted across multiple site‐years in Michigan with three planting dates (early: April 25–May 10; mid: May 11–25; and late: May 26–June 10) and/or four seeding rates (ranging from 69,160 to 113,620 seeds ha−1, in increments of 14,800 seeds ha−1). Mid‐planting yielded 12%–15% less forage than early and late plantings, partly due to greater insect feeding injury and fungal infections observed in the former. Neutral detergent fiber digestibility, starch, and crude protein concentration were greatest for early planting. Greater predicted milk per hectare and milk per megagram for early planting also indicated superior silage quality. Increasing seeding rate increased insect feeding and ear rot injury only when severity was >5% and >15%, respectively. The impact of increasing seeding rate on dry forage yield was specific to each site‐year. Overall, results showed that early planting of silage corn helps to escape insect and disease pressure and provides better yield and quality, while seeding rate response is variable and dependent on the field environment. Core Ideas: Escaping insect feeding and ear rots by altering the planting date is critical to protect yield and forage quality.Delaying silage corn planting reduced forage neutral detergent fiber digestibility.Insect feeding severity and ear rot increased at high seeding rates (≥98,800 seeds ha−1).Higher seeding rates led to reduction in neutral detergent fiber digestibility and predicted milk yield. [ABSTRACT FROM AUTHOR]

Mycotoxins are secondary metabolites produced by fungi that, depending on the type and exposure levels, can be a threat to human and animal health. When multiple mycotoxins occur together, their risk effects on human and animal health can be additive or synergistic. Little information is known about the specific types of mycotoxins or their co-occurrence in the state of Michigan and the Great Lakes region of the United States. To understand the types, incidences, severities, and frequency of co-occurrence of mycotoxins in maize grain (Zea mays L.), samples were collected from across Michigan over two years and analyzed for 20 different mycotoxins. Every sample was contaminated with at least four and six mycotoxins in 2017 and 2018, respectively. Incidence and severity of each mycotoxin varied by year and across locations. Correlations were found between mycotoxins, particularly mycotoxins produced by Fusarium spp. Environmental differences at each location played a role in which mycotoxins were present and at what levels. Overall, data from this study demonstrated that mycotoxin co-occurrence occurs at high levels in Michigan, especially with mycotoxins produced by Fusarium spp., such as deoxynivalenol. [ABSTRACT FROM AUTHOR]

The persistence of high values of relative humidity for several hours to a few days has wide‐ranging implications for natural and human systems. Among its many impacts, persistent high relative humidity contributes to reduced atmospheric visibility, fog frequency and duration, road and powerline icing, the occurrence of foliar plant disease and the temperature at which heat‐related morbidity and mortality can occur. Despite this, the characteristics of humidity spells—including shifts with climate change—are rarely investigated and consequently poorly understood. Hourly relative humidity, precipitation and temperature for 35 locations in the Lower Peninsula (LP) of Michigan during 2003–2017, and for seven locations during 1973–2017, were used to assess, by biweekly periods, spatial, intra‐annual and inter‐annual variations in the characteristics of relative humidity spells. Two humidity thresholds that accommodate a wide range of applications were used: (1) high relative humidity (HRH), defined as hourly values ≥60%, and extremely high relative humidity (EHRH), defined as hourly values ≥85%. Extended HRH and EHRH spells are frequent across the LP, with HRH spells often spanning 36 hr or longer and EHRH spells commonly persisting more than 12 hr. The probability of HRH and EHRH spells generally decreased with time during 1973–2017, particularly later in the period. Although most spells initiate in the late afternoon and early evening hours, this diurnal preference is less evident as spell length increases, especially for EHRH spells. Furthermore, precipitation is more likely to occur with EHRH spells compared to HRH spells. The orientation and strength of spatial gradients in average annual spell frequency are highly dependent on the choice of humidity and duration thresholds and the temperatures accompanying the spells. This study represents the first comprehensive analysis of the persistence of humidity spells and illustrates the potential usefulness of temporally‐flexible climatological summaries relevant for a wide range of applications. [ABSTRACT FROM AUTHOR]

The causal agent of Phytophthora stem and root rot (PRR), Phytophthora sojae Gerdemann and Kaufman, is a major pathogen of soybean (Glycine max (L.) Merr.). Integrated pest management strategies for PRR consists of planting varieties with effective single-dominant resistance genes (Rps genes), partial resistance (field tolerance) and seed treatments containing oomicides such as ethaboxam and mefenoxam. To investigate the interaction of PRR partial resistance and seed treatment on soybean stand, vigor and yield, soybean plots were inoculated in-furrow with P. sojae isolates able to overcome the Rps genes present in the planted soybean varieties in Michigan in 2018 as well as Michigan, Indiana, and Minnesota in 2019. Nine commercial soybean varieties with contrasting Phytophthora resistance profiles received three different seed treatments: 1) non-treated, 2) base (ipconazole and clothianidin), and 3) Intego Suite (base + ethaboxam and mefenoxam) in Michigan, with four of the same varieties and seed treatments being planted in Indiana and Minnesota. Soybean stand was significantly protected with Intego Suite in the nine varieties tested in Michigan 2018, eight of nine in Michigan 2019, and two of four in Indiana 2019. Significant differences in yield between seed treatments were observed in three varieties of nine in Michigan 2018. The effect of partial resistance on plant health and final yields was not apparent given the supplied company partial resistance scores across locations and years. In conclusion, this study finds that oomicide seed treatments are useful in protecting soybean stand under PRR disease pressure in multiple locations in the Midwest United States. • Intego Suite can significantly protect stand in the presence of Phytophthora sojae. • The impact of companies Phytophthora tolerance rating on yield were inconclusive. • A more descriptive Phytophthora tolerance assessment could aid in-field management. [ABSTRACT FROM AUTHOR]

Fusarium graminearum is perhaps best known for causing head blight in wheat and ear and stalk rot in corn. However, F. graminearum can also cause seedling diseases and root rot on many field crops including wheat, corn, soybean, and dry bean. In 2019, a new Succinate Dehydrogenase Inhibitor (SDHI) fungicide, pydiflumetofen (Syngenta, Switzerland), was registered for management of Fusarium Head Blight of wheat and corn ear rot. Here, we determined the sensitivity of isolates of F. graminearum from wheat, corn, soybean and dry bean from Michigan to this new active ingredient. In vitro sensitivity of 94 isolates was assessed with a poison plate mycelial growth assay, and a subset with 21 isolates was also tested with a spore germination assay. The effective concentration that reduced growth or germination by 50% (EC 50) was determined for each isolate. Mycelial growth EC 50 values ranged from 0.008 to 0.263 μg/mL, with a mean of 0.060 μg/mL. EC 50 values for spore germination assays ranged from 0.167 to 0.538 μg/mL, with a mean of 0.321 μg/mL. This study demonstrates both mycelial growth and spore germination are inhibited by this new chemistry in vitro. This data also establishes baseline sensitivity values of Michigan populations of F. graminearum before widespread application of this chemistry on commercial fields. • In vitro baseline sensitivity was determined for the new fungicide, pydiflumetofen. • EC50 values for mycelial growth of 94 isolates ranged from 0.008 to 0.263 μg/mL. • EC50 values for spore germination ranged from 0.167 to 0.538 μg/mL for 21 isolates. • Pydiflumetofen could be valuable for FHB management in wheat and corn. [ABSTRACT FROM AUTHOR]

Presents a summary of the research article `Trends in the Prevalence of Asthma Hospitalization in the 5- to 14-Year Old Michigan Medicaid Population, 1980 to 1986,' by B.B. Gertsman, L.A. Bosco et al, published in a 1993 issue of `Journal of Allergy and Clinical Immunology.' Relationship between race and asthma hospitalization; Variation by social class.

Although oomycete species can contribute to significant losses in soybean plant density, root mass and yield, they are often underrepresented in high-throughput sequencing studies. In this study, soybean oomycete rhizosphere communities were characterized over two years from locations with and without historical disease pressure. The goals of this research were to examine the effect of location, soybean genotype, and seed treatment on oomycete communities. Soybean oomycete rhizosphere communities were dominated by Pythium , but community composition differed depending on the location and year. Pythium ultimum var. ultimum was the most abundant oomycete OTU accounting on average for >30% relative abundance in high disease pressure sites. However, sites without historical disease pressure were not devoid of oomycete plant pathogens indicating that historical disease pressure may be due to an imbalance of species, rather than simply the presence or absence of highly pathogenic species. High-disease pressure sites contained more oomycete taxa and were less even. There was no substantial evidence of seed treatment or soybean genotype impacting oomycete community composition or diversity, however, plant density and root biomass increased with the addition of neonicotinoid insecticides. Overall, this study represents an improvement of our understanding of oomycete communities in soybean rhizosphere and the impacts of agronomic factors on oomycete diversity. • Soybean rhizosphere samples dominated by Pythium • Soybean seed treatment and genotype did not impact oomycete rhizosphere diversity. • Location and year impact oomycete soybean rhizosphere diversity. [ABSTRACT FROM AUTHOR]

Formally described in 2009, Phytophthora sansomeana is a pathogen of increasing interest in native, agricultural, and horticulturally important plant species. The objective of this study was to elucidate the symptomatic and asymptomatic host range of P. sansomeana on six agricultural crop species commonly used in field crop rotations in Michigan. In addition, sensitivity to oomicides commonly used in seed treatments, including oxathiapiprolin, mefenoxam, ethaboxam, and pyraclostrobin, was performed to aid in disease management recommendations. Plant biomass, quantity of P. sansomeana DNA in roots, and reisolations were used to assess pathogenicity and virulence of 18 isolates of P. sansomeana on each plant species using an inoculated seedling growth chamber assay. Isolates displayed varying levels of virulence to the hosts tested. Reisolations were completed for each plant species tested, and varying quantities of P. sansomeana DNA were found within all plant species root samples. Corn, wheat, soybean, dry bean, and winter cereal rye plants were symptomatic hosts with significant reduction observed in the total plant biomass. No significant reduction in total plant biomass was observed in oats, and oat roots harbored the least amount of P. sansomeana DNA. No P. sansomeana isolates were insensitive to the oomicide compounds tested with mean absolute inhibition (EC 50 ) values of fungicide required for 50% growth inhibition values of 7.8 × 10 -2 μg/ml for mefenoxam, 1.13 × 10 -1 μg/ml for ethaboxam, 2.6 × 10 -2 μg/ml for oxathiapiprolin, and 3.04 × 10 -1 μg/ml for pyraclostrobin. These results suggest that common crop rotations in Michigan may not be a viable option to reduce soilborne inoculum accumulation and oomicide seed treatments could be considered for early-season management of P. sansomeana ., Competing Interests: The author(s) declare no conflict of interest.

Identifying the pathotype structure of a Phytophthora sojae population is crucial for the effective management of Phytophthora stem and root rot of soybean (PRR). P . sojae has been successfully managed with major resistance genes, partial resistance, and fungicide seed treatments. However, prolonged use of resistance genes or fungicides can cause pathogen populations to adapt over time, rendering resistance genes or fungicides ineffective. A statewide survey was conducted to characterize this pathotype structure and fungicide sensitivity of P . sojae within Michigan. Soil samples were collected from 69 fields with a history of PRR and fields having consistent plant stand establishment issues. Eighty-three isolates of P . sojae were obtained, and hypocotyl inoculations were performed on 14 differential soybean cultivars, all of which carry a single Rps gene or no resistance gene. The survey identified a loss of effectiveness of Rps genes 1b, 1k, 3b, and 6, compared with a previous survey conducted in Michigan from 1993 to 1997. Three effective resistance genes were identified for P . sojae management in Michigan; Rps 3a, 3c, and 4. Additionally, the effective concentration of common seed treatment fungicides to inhibit mycelial growth by 50% ( EC 50 ) was determined. No P . sojae isolates were insensitive to the tested chemistries with mean EC 50 values of 2.60 × 10 -2 μg/ml for ethaboxam, 3.03 × 10 -2 μg/ml for mefenoxam, 2.88 × 10 -4 μg/ml for oxathiapiprolin, and 5.08 × 10 -2 μg/ml for pyraclostrobin. Results suggest that while there has been a significant shift in Rps gene effectiveness, seed treatments are still effective for early season management of this disease.

Fusarium root rot (FRR) is a global limiter of dry bean ( Phaseolus vulgaris L.) production. In common bean and other legumes, resistance to FRR is related to both root development and root architecture, providing a breeding strategy for FRR resistance. Here, we describe the relationships between root traits and FRR disease symptoms. Using "shovelomics" techniques, a subset of recombinant inbred lines was phenotyped for root architecture traits and disease symptoms across three Michigan fields, including one field with artificially increased Fusarium brasiliense disease pressure. At the early growth stages, stem diameter, basal root number, and distribution of hypocotyl-borne adventitious roots were all significantly related to FRR disease scores. These results demonstrate that root architecture is a component of resistance to FRR in the field at early growth stages (first expanded trifoliate) complementing previous studies that evaluated root traits at later developmental stages (flowering, pod fill, etc.). Correlation matrices of root traits indicate that resistant and susceptible lines have statistically different root systems and show that basal root number is a key feature in resistant root systems while adventitious root distribution is an important feature in susceptible root systems. Based on the results of this study, selection for increased basal root number, increased adventitious root number, and even distribution of adventitious roots in early growth stages (first expanded trifoliate) would positively impact resistance to FRR.

In total, 52 uniform field experiments were conducted in Illinois, Indiana, Iowa, Michigan, South Dakota, and Wisconsin in the United States and Ontario, Canada from 2013 to 2017 comparing crop protection products against sudden death syndrome (SDS) of soybean. Data were analyzed using meta-analytic models to summarize the relationship between foliar disease index (FDX) and yield. For each study, correlation and regression analyses were performed separately to determine three effect sizes: Fisher's transformation of correlation coefficients ( Z r ), intercept (β 0 ), and slope (β 1 ). Random- and mixed-effect meta-analyses were used to summarize the effect sizes. Study- and location-specific moderator variables FDX (low < 10% and high ≥ 10%), date of planting (early = prior to 7 May, conventional = 7 to 21 May, and late = after 21 May) cultivar (susceptible and partially resistant to SDS), study location, and growing season were used as fixed effects. The overall mean effect sizes of transformed correlation coefficient [Formula: see text] r was -0.41 and different from zero ( P < 0.001), indicating that yield was negatively correlated with FDX. The [Formula: see text] r was affected by disease level ( P < 0.01) and cultivar ( P = 0.02), with a greater effect at higher disease levels and with susceptible cultivars. The mean [Formula: see text] 0 was 4,121 kg/ha and mean [Formula: see text] 1 was -21 kg/ha/% FDX and were different from zero ( P < 0.01). Results from these data indicate that, for every unit of FDX increase, yield was decreased by 0.5%. Study locations and year affected the [Formula: see text] 0 , whereas none of the moderator variables significantly affected [Formula: see text] 1.

Species within clade 2 of the Fusarium solani species complex (FSSC) are significant pathogens of dry bean ( Phaseolus vulgaris ) and soybean ( Glycine max ), causing root rot and/or sudden death syndrome (SDS). These species are morphologically difficult to distinguish and often require molecular tools for proper diagnosis to a species level. Here, a TaqMan probe-based quantitative PCR (qPCR) assay was developed to distinguish Fusarium brasiliense from other closely related species within clade 2 of the FSSC. The assay displays high specificity against close relatives and high sensitivity, with a detection limit of 100 fg. This assay was able to detect F. brasiliense from purified mycelia, infected dry bean roots, and soil samples throughout Michigan. When multiplexed with an existing qPCR assay specific to Fusarium virguliforme , accurate quantification of both F. brasiliense and F. virguliforme was obtained, which can facilitate accurate diagnoses and identify coinfections with a single reaction. The assay is compatible with multiple qPCR thermal cycling platforms and will be helpful in providing accurate detection of F. brasiliense . Management of root rot and SDS pathogens in clade 2 of the FSSC is challenging and must be done proactively, because no midseason management strategies currently exist. However, accurate detection can facilitate management decisions for subsequent growing seasons to successfully manage these pathogens.

As complete host resistance in soybean has not been achieved, Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum continues to be of major economic concern for farmers. Thus, chemical control remains a prevalent disease management strategy. Pesticide evaluations were conducted in Illinois, Iowa, Michigan, Minnesota, New Jersey, and Wisconsin from 2009 to 2016, for a total of 25 site-years ( n = 2,057 plot-level data points). These studies were used in network meta-analyses to evaluate the impact of 10 popular pesticide active ingredients, and seven common application timings on SSR control and yield benefit, compared with not treating with a pesticide. Boscalid and picoxystrobin frequently offered the best reductions in disease severity and best yield benefit ( P < 0.0001). Pesticide applications (one- or two-spray programs) made during the bloom period provided significant reductions in disease severity index (DIX) ( P < 0.0001) and led to significant yield benefits ( P = 0.0009). Data from these studies were also used in nonlinear regression analyses to determine the effect of DIX on soybean yield. A three-parameter logistic model was found to best describe soybean yield loss (pseudo- R 2 = 0.309). In modern soybean cultivars, yield loss due to SSR does not occur until 20 to 25% DIX, and considerable yield loss (-697 kg ha -1 or -10 bu acre -1 ) is observed at 68% DIX. Further analyses identified several pesticides and programs that resulted in greater than 60% probability for return on investment under high disease levels.

Sudden death syndrome (SDS), caused by members of Fusarium solani species complex (FSSC) clade 2, is a major and economically important disease in soybean worldwide. The primary causal agent of SDS isolated to date in North America has been F. virguliforme . In 2014 and 2016, SDS symptoms were found in two soybean fields located on the same farm in Michigan. Seventy Fusarium strains were isolated from roots of the SDS-symptomatic soybeans in two fields. Phylogenetic analysis of partial sequences of elongation factor-1α, the nuclear ribosomal DNA intergenic spacer region, and the RNA polymerase II beta subunit revealed that the primary FSSC species isolated was F. brasiliense (58 and 36% in each field) and the remaining Fusarium strains were identified as F. cuneirostrum , F. phaseoli , an undescribed Fusarium sp. from FSSC clade 2, and strains in FSSC clade 5 and FSSC clade 11. Molecular identification was supported with morphological analysis and a pathogenicity assay. The soybean seedling pathogenicity assay indicated that F. brasiliense was capable of causing typical foliar SDS symptoms. Both root rot and foliar disease severity were variable by strain, just as they are in F. virguliforme . Both FSSC 5 and FSSC 11 strains were also capable of causing root rot, but SDS foliar symptoms were not detected. To our knowledge, this is the first report of F. brasiliense causing SDS in soybean in the United States and the first report of F. cuneirostrum , F. phaseoli , an as-yet-unnamed Fusarium sp., and strains in FSSC clade 5 and FSSC clade 11 associated with or causing root rot of soybean in Michigan.

Pythium ultimum causes seedling damping-off and root and crown rot in greenhouse ornamental plants. To understand the population dynamics and assess population structure of P. ultimum in Michigan floriculture crops, simple sequence repeats (SSRs) were developed using the previously published P. ultimum predicted transcriptome. A total of 166 isolates sampled from 2011 to 2013 from five, one, and three greenhouses in Kalamazoo, Kent, and Wayne Counties, respectively, were analyzed using six polymorphic and fluorescently labeled SSR markers. The average unbiased Simpson's index (λ u , 0.95), evenness ( E 5 is not a recent introduction into Michigan greenhouses. Analyses revealed a clonal population, with limited differentiation among seasons, hosts, and counties sampled. Results also indicated the presence of common genotypes among years, suggesting that sanitation measures should be enhanced to eradicate resident P. ultimum is not a recent introduction into Michigan greenhouses. Analyses revealed a clonal population, with limited differentiation among seasons, hosts, and counties sampled. Results also indicated the presence of common genotypes among years, suggesting that sanitation measures should be enhanced to eradicate resident P. ultimum in Michigan and facilitate improvement of control strategies.P. ultimum in Michigan and facilitate improvement of control strategies.

Identifying the optimal timing for fungicide application is crucial in order to maximize the control of Sclerotinia stem rot (SSR), which is caused by Sclerotinia sclerotiorum. In this study, the impact of canopy closure and soil temperature on apothecia production was investigated to optimize fungicide application timing. Replicated soybean plots with a row spacing of 0.36 and 0.38 or 0.76 m were established in 2015 and 2016 in an irrigated soybean field at Michigan State University's Montcalm Research Center. The number of apothecia and ascospores and the incidence of SSR were monitored two times per week for 10 to 12 weeks. In both row-spacing trials, apothecia were observed earlier in 2016 (before the R1 growth stage) than in 2015 (between R1 and R2). The maximum number of apothecia was 50 times higher with the 0.36-m row spacing than with the 0.76-m row spacing in 2015 but was 2.5 times higher with the 0.76-m row spacing than with the 0.38-m row spacing in 2016, though the overall numbers were much lower in 2016. The apothecia distribution pattern was synchronized with the canopy closure pattern and the soil temperature profile. The peak number of apothecia was observed when canopy closure reached at least 50% and when average soil temperature in the row was between 21.5 and 23.5°C. In 91% of the cases, the presence of apothecia was observed when the percentage of light blocked was 70%, and no apothecia germinated in the absence of light or under full light exposure. During the first 50 days after plant emergence, the rate of canopy closure was higher in 2016 than in 2015, and the first diseased plant was observed earlier in 2016 (R2) than in 2015 (R5). Canopy closure and the distance of the sampling point from the soybean row explained much of the variability in the number of apothecia. These results can partially explain the inconsistent efficacy of fungicide applications based on the soybean growth stage and will be helpful for informing disease models and fine-tuning fungicide application strategies.

Sclerotinia stem rot (SSR) epidemics in soybean, caused by Sclerotinia sclerotiorum, are currently responsible for annual yield reductions in the United States of up to 1 million metric tons. In-season disease management is largely dependent on chemical control but its efficiency and cost-effectiveness depends on both the chemistry used and the risk of apothecia formation, germination, and further dispersal of ascospores during susceptible soybean growth stages. Hence, accurate prediction of the S. sclerotiorum apothecial risk during the soybean flowering period could enable farmers to improve in-season SSR management. From 2014 to 2016, apothecial presence or absence was monitored in three irrigated (n = 1,505 plot-level observations) and six nonirrigated (n = 2,361 plot-level observations) field trials located in Iowa (n = 156), Michigan (n = 1,400), and Wisconsin (n = 2,310), for a total of 3,866 plot-level observations. Hourly air temperature, relative humidity, dew point, wind speed, leaf wetness, and rainfall were also monitored continuously, throughout the season, at each location using high-resolution gridded weather data. Logistic regression models were developed for irrigated and nonirrigated conditions using apothecial presence as a binary response variable. Agronomic variables (row width) and weather-related variables (defined as 30-day moving averages, prior to apothecial presence) were tested for their predictive ability. In irrigated soybean fields, apothecial presence was best explained by row width (r = -0.41, P < 0.0001), 30-day moving averages of daily maximum air temperature (r = 0.27, P < 0.0001), and daily maximum relative humidity (r = 0.16, P < 0.05). In nonirrigated fields, apothecial presence was best explained by using moving averages of daily maximum air temperature (r = -0.30, P < 0.0001) and wind speed (r = -0.27, P < 0.0001). These models correctly predicted (overall accuracy of 67 to 70%) apothecial presence during the soybean flowering period for four independent datasets (n = 1,102 plot-level observations or 30 daily mean observations).