Nabin Kumar Dangal

This study investigates the impact of seeding rate, cultivar architecture, and fungicide application on soybean canopy penetration, disease severity, and yield. Field trials conducted in Iowa in 2022, 2023, and 2025 included two soybean cultivars: Xitavo 2282E, a low-branching cultivar, and Xitavo 2501E, a high-branching cultivar, planted at three seeding rates: low (247,105 seeds ha ⁻¹ ), medium (345,948 seeds ha ⁻¹ ), and high (444,798 seeds ha ⁻¹ ). A fungicide containing mefentrifluconazole, fluxapyroxad, and pyraclostrobin was applied at 584.6 ml ha ⁻¹ at the beginning pod (R3) stage using a tractor-mounted sprayer. Spray coverage in the upper canopy was uniform across cultivars and seeding rates, while in the lower canopy, Xitavo 2282E received 41% greater coverage than Xitavo 2501E. Frogeye leaf spot (FLS) and Septoria brown spot (SBS) severity varied among site-years, with Xitavo 2282E exhibiting more disease than Xitavo 2501E. Seeding rate influenced SBS, with higher populations associated with increased disease. Low seeding rates increased branch and node numbers, and Xitavo 2501E had more branches and nodes than Xitavo 2282E. Grain yield increased with seeding rate, while cultivar had no significant effect. Fungicide application increased 100-seed weight and yield modestly (approximately 2%). These results indicate that planting population is the primary driver of soybean productivity, while canopy architecture affects spray penetration but not yield response under low disease pressure. Integrating cultivar selection, seeding rate, and canopy structure can enhance soybean management and fungicide efficiency.

Fungicide application method and crop canopy structure can influence spray deposition, disease control, and yield in corn ( Zea mays L.), yet their interactions remain poorly understood, particularly in short-stature hybrids. Field experiments were conducted in Iowa and Kentucky during 2023 and 2024 to evaluate the effects of hybrid architecture (short versus tall stature) and fungicide application method (aerial, ground, unmanned aerial vehicle [UAV], and 360 Undercover) on spray deposition, foliar disease severity, and grain yield. Fungicide deposition was quantified using a fluorescent tracer dye measured across canopy positions and distances from the spray swath center. Deposition differed among application methods, canopy positions, and row locations, with ground and UAV applications generally providing greater deposition than aerial applications. Deposition was greatest in the upper canopy and declined toward lower canopy positions, whereas 360 Undercover improved lower-canopy deposition. Despite these differences, fungicide applications reduced foliar disease severity relative to the nontreated control across environments, with minor differences among application methods. Tar spot ( Phyllachora maydis ) and southern rust ( Puccinia polysora ) were observed in Iowa, and gray leaf spot ( Cercospora zeae-maydis , C. zeina ) occurred in Kentucky. Grain yield increased with fungicide application, but differences among application methods were small and inconsistent. Overall, the results indicate that multiple application systems can provide effective disease control and yield protection when fungicides are applied at the appropriate growth stage and that adequate deposition, rather than maximum deposition, is sufficient for managing major foliar diseases in corn. Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Sudden death syndrome (SDS), caused by Fusarium virguliforme, is a major yield-limiting disease of soybean in the United States and Canada. Field trials in 2020 and 2021 across 13 U.S. states and Ontario, Canada, evaluated two SDS-targeted seed treatments and soybean cultivars: one susceptible (S) and one moderately resistant (MR) to SDS. Treatments included a base (prothioconazole + metalaxyl + penflufen, metalaxyl, and imidacloprid), base + fluopyram, and base + pydiflumetofen. Data collection included root rot ratings, SDS foliar symptoms, and yield. Under high SDS pressure (foliar disease index [FDX] ≥ 10), both SDS-targeted seed treatments and MR cultivars significantly reduced foliar symptoms (71 to 80%) compared with the base seed treatment and susceptible cultivars. Although 2020 and 2021 were not epidemic years for SDS, consistent reductions in SDS were observed. In the absence of disease, S cultivars produced greater yield than MR, but under high SDS and low soybean cyst nematode (SCN) pressure (3 of soil), the MR cultivars produced greater yield than the S cultivars. Only the base + pydiflumetofen treatment maintained greater yield in the absence of SDS. When SDS pressure was high (FDX ≥ 10), both SDS-targeted treatments had 7.0 to 9.0% more yield than the base. Under combined high SDS and SCN pressure (≥2,000/100 cm ³ of soil), only base + fluopyram preserved yield more than the base treatment. These results provide valuable insights for future SDS management through cultivar selection and seed treatments.

Frogeye leaf spot, caused by Cercospora sojina, and Septoria brown spot, caused by Septoria glycines, are foliar diseases of mungbean ( Vigna radiata). This report evaluates fungicide and insecticide applications at different reproductive growth stages for managing foliar disease and insect-related yield loss. A field trial was conducted in 2024 in central Iowa on cultivar ‘Berken’ to assess applications at R1, R3, and R5. Results indicate that insecticide applications at R3 reduced pod abortion and protected yield, whereas fungicide applications reduced foliar disease but did not affect yield. These findings inform pest management timing for mungbean in the U.S. Midwest.

A network meta-analysis was conducted to assess the efficacy of fungicides in reducing disease and protecting yield in corn. Uniform protocols were designed to test the efficacy of 12 widely available corn fungicides applied at one of the following timings: in-furrow with the seed at planting, applied 5.1 cm to the side and 5.1 cm below the seed at planting, 10 to 12 leaves with a visible collar, tasseling to silking (VT/R1), or milk stage. A total of 152 trials were conducted across 18 states in the United States and Ontario, Canada, from 2019 to 2022. Studies were analyzed using network meta-analyses to determine the fungicide efficacy and expected yield benefit of individual products compared with a nontreated control (NTC). All fungicides significantly reduced disease severity compared with the NTC ( P < 0.001), and all fungicides resulted in greater yields compared with the NTC, except for Xyway LFR. Final disease severity influenced yield effect size, with fungicide application resulting in a greater yield effect size when final disease severity exceeded 5%. Fungicide application timing also influenced yield effect size, with fungicides applied at VT/R1 resulting in significantly lower disease (–7.6%) compared with the NTC. The yield effect size was typically greater in studies with the fungicide applied at VT/R1 compared with applications occurring at planting. Economic analyses concluded that expected net benefits were positive for all fungicides tested except for Delaro Complete and Xyway LFR. Most fungicides resulted in greater breakeven probabilities with increasing disease severity. The results emphasize that fungicide applications occurring at VT/R1 and when disease severity exceeds 5% are more likely to result in a positive economic gain. [ ] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Sudden death syndrome (SDS), primarily caused by Fusarium virguliforme, threatens soybean (Glycine max) production across the United States and Ontario, Canada. SDS thrives in cool, wet soils, with post-planting rainfall exacerbating disease, making pre-planting management strategies like resistant cultivars and seed treatments crucial. This study evaluated biological and chemical seed treatments on resistant and susceptible soybean cultivars across 14 locations in 2022 and 15 locations in 2023. Data collection included final stand counts, root rot severity, foliar SDS severity index (FDX), and yield. Trials were categorized into high (FDX ≥ 10%) or low (FDX < 10%) disease severity locations based on the non-treated control (NTC). In high disease locations, cultivar and seed treatment significantly (P ≤ 0.01) influenced FDX, root rot, and yield. The base+fluopyram and base+fluopyram+natamycin treatment reduced FDX by 6.7% and increased yield by 288.5 kg/ha over the non-treated. The resistant cultivar reduced FDX by 9.7% and root rot by 2.1%, while increasing yield by 247.7 kg/ha relative to the susceptible cultivar. Under low disease pressure, cultivar selection remained significant, with resistance reducing FDX by 2.4% and root rot by 0.8%, and improving yield by 445.5 kg/ha. In contrast, the effects of seed treatment were not significant in the low disease severity environments. No seed treatments reduced FDX or root rot and only base+fluopyram and base+fluopyram+natamycin increased yield (+254 to 301 kg/ha) compared to the non-treated in the low disease severity environments. Cultivar resistance remains the most effective SDS management strategy, with seed treatments providing significant benefits under high disease pressure.

Mungbean ( Vigna radiata L. Wilczek) is a warm-season legume native to the Indo-Myanmar region. In North America, it is adopted as a rotational or double crop due to its agronomic versatility, although cultivation remains limited. The extent to which mungbean production is constrained by insect and disease pests in the United States is unclear. Field experiments were conducted in 2023 and 2024 in Story County, IA, to assess the effect of fungicide and insecticide application timing on disease severity, defoliation, pod abortion, and yield. Two cultivars, Berken and OK2000, were evaluated. A tank mix (mefentrifluconazole + fluxapyroxad + pyraclostrobin and lambda-cyhalothrin) was applied at five reproductive stages from beginning flower (R1) to beginning maturity (R5) in a two-factorial randomized complete block design. Plots were inoculated with Septoria glycines and Cercospora sojina to simulate disease pressure. Applications at beginning pod (R2), beginning seed filling (R3), and full seed (R4) significantly reduced disease and pod abortion while protecting yield. Linear regression analyses identified insect-induced pod abortion as the primary driver of yield loss (adjusted R ² = 0.30), with a moderate inverse correlation ( r = −0.56) between pod loss and yield. These results highlight the importance of pesticide application timing, particularly at R3, to protect mungbean yield. Future research should identify the specific insect pests responsible for yield reduction.

Visual assessments of the severity of plant diseases often vary among evaluators. A pipeline was developed for quantifying frogeye leaf spot, caused by Cercospora sojina, in soybean using three-dimensional (3D) imaging techniques. Soybean leaves were collected from field and humidity chamber environments following inoculation with C. sojina. Flatbed scanners were used to acquire conventional (2D) images, and a Peel 3D scanner was used to generate 3D models, producing JPG and OBJ/PLY files. Image segmentation was conducted using k-means clustering to classify 2D and 3D pixels into healthy, diseased, or mixed categories. Point cloud data from 3D scans were processed and analyzed with CloudCompare and R software to evaluate the percentage of leaf area occupied by lesions. Statistical comparison between 2D and 3D measurements produced a concordance correlation coefficient of 0.828, indicating substantial agreement, although the 3D method tended to overestimate disease severity at low levels (<10%) and underestimate severity at higher levels (≥10%). Lighting inconsistencies during 3D scanning affected accuracy of the estimates. Despite these limitations, 3D imaging shows potential as a complementary tool to traditional images for evaluating disease symptoms. Additionally, the dataset made available provides a foundation for future applications in machine learning and automated disease quantification in plant pathology. Continued refinement of imaging and analysis methods is essential for improving the accuracy of severity estimates and enabling high-throughput, objective phenotyping in disease quantification for comparison of treatments or screening for host resistance.

Ivyleaf morningglory (Ipomoea hederacea L.) is a prevalent weed in Iowa. This weed was found in corn field with approx. >50% incidence and from 10-40% severity of white pustules in Boone County during summer 2022, 2023, and 2024. The weed was observed with irregularly yellow-necrotic spots on the adaxial surface of leaves with white pustules on the abaxial side. Initially, the adaxial surface of the infected leaf exhibited yellow irregular spots that gradually turned brown and necrotic (Fig. S1A). On the yellow irregular spots of the abaxial surface, tiny, powdery, and chalky-white-cream sori appeared (Fig. S1B). Sori were observed individually or in clusters in somewhat as in concentric rings (Fig. S1C-D). Fresh, symptomatic leaves were collected for microscopic and molecular identification. If sori remained unopened, a sterile syringe was used to scrape sporangia onto a glass slide with blue lactophenol to inspect under a light microscope. Sporangia were hyaline, cylindrical-rectangular, 15.8 to 20.9 µm long (mean 17.9 µm, SE 0.46 µm), and 12.8 to 17.6 µm wide (mean 15.6 µm, SE 0.6 µm; Fig. S1E) (n = 20). Microscopic observations indicated that the causal agent was Albugo sp. Voucher specimens (accession nos. 458429 & 458430) were deposited in the Ada Hayden herbarium from Iowa State University. High amounts of sporangia were collected using a sterile elongated flock swab 6 in HydraFlock (Puritan Medical Products, Guilford, ME) for DNA extraction and pathogenicity test. Fungal genomic DNA was isolated separately from sporangia sori by Qiagen DNeasy Plant Mini kit (Qiagen, Valencia, CA). For molecular identification, two samples from different plants were processed (ALBUG_03 and ALBUG_04). The internal transcribed spacer (ITS1-O/LR0 primers) region and cox-2 (cox2-F/cox2-RC4 primers) gene were amplified by PCR (Kim et al. 2019; Choi et al. 2015). In both cases, amplicons (600 bp ITS region; 840 bp cox-2 region) were purified by PCR cleanup ExoSAP-IT express (Invitrogen, Waltham, MA) and further subjected to Sanger sequencing. Both sequences showed similarity to A. ipomoeae-panduratae in ITS (99.87% with reference strain DQ643920) and cox-2 (100% with reference strain AY913804) region. A phylogenetic tree was built with sequences of these two genes of Albugo species and related genera (Fig. S2). Both isolates-sequences were molecularly identical, then the isolate ALBUG_03 strain from this study, was uploaded as representative in GenBank as Albugo ipomoeae-panduratae (PQ452335 and PQ489431). For the pathogenicity test, ivyleaf morningglory seeds were surface disinfested with ethanol 70% for 30 s and NaOCl (0.8%) for 1 min, rinsed twice in sterile water and sown into autoclaved compost:perlite mix (50:50). Zoospores were produced from a sporangiospores- suspension of sterile water (10⁵/ml) as described by Pidskalny & Rimmer (1985) with slight modifications. Suspension was shocked at 4°C for an hour and placed in the dark at 25°C. After 24 h, the zoospores were inoculated on 14 days old-healthy plants by spraying the suspension with 0.1% Tween 20. After the inoculation, plants were kept inside a plastic bag for 3 days and then removed. Plants were placed in a growth chamber at 25°C and 70% RH. Symptoms resembling the original white rust disease appeared at 10 DAI, and sporangia were seen under microscope; controls remained symptomless (Fig. S1F). White rust has been reported previously in Iowa and nearby states; however, to our knowledge, this is the first report of Albugo ipomoeae-panduratae being identified as the causal pathogen for white rust on ivyleaf morningglory in Iowa. It is important to document the actual identity of this oomycete, as this pathogen has a broad host range within Ipomoea and Convolvulus genera plants, including important food crops such as sweet potato (I. batatas).

Sudden death syndrome (SDS), caused primarily by Fusarium virguliforme, can result in significant yield losses in soybean in the United States. Fluopyram is a seed treatment used for SDS management; however, its efficacy is not consistent. Little is known about how seed treatments are affected by the application of fertilizers. Field trials were conducted in Iowa from 2021 to 2023 to evaluate a nontreated control (NTC), a base (Allegiance FL + Stamina + Systiva XS Xemium brand + Poncho 600 + Flo Rite 1706 + Color Coat) seed treatment, and a base combined with various nanofertilizers (NanoStress, NanoPhos, NanoK, and NanoN, each at 292 ml/ha [4 fl. oz./acre]) with and without fluopyram (0.15 mg/seed). Combined analysis across 3 years revealed that base + fluopyram + NanoN resulted in a significantly lower foliar disease index (FDX) than the base, whereas base + fluopyram + NanoK and base + fluopyram + NanoPhos resulted in significantly more yield than the NTC. Other field trials were conducted in Iowa and Wisconsin during 2022 and 2023 to compare the effects of base, base combined with NanoStress + NanoN, 168 kg/ha N, fluopyram (0.15 mg/seed), fluopyram + NanoStress + NanoN, and fluopyram + 168 kg/ha N. The results showed significant effects on FDX and yield. Base + fluopyram + 168 kg/ha N significantly reduced FDX and increased yield as compared with the base treatment. These findings suggest that nanofertilizers and nitrogen fertilizers may enhance the performance of fluopyram, but further research is needed to explore how fertility influences host-pathogen interactions. [ ] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .