Low Disease Pressure Research Articles

Optimizing fungicide programs for peanut leaf spot management in Southeast Alabama: A case for reducing chlorothalonil use

Early leaf spot (caused by Passalora arachidicola) and late leaf spot (Nothopassalora personata) are the most damaging fungal diseases of peanuts (Arachis hypogaea L.) in the southeastern United States. Producers rely heavily on single-site fungicides, which pose a moderate to high risk for resistance development. To mitigate this risk, chlorothalonil, the predominate multi-site fungicide used to manage leaf spot diseases in peanuts, is the backbone of leaf spot spray programs. However, the future availability of chlorothalonil in agriculture is at risk due to regulatory decisions and toxicity issues. Thus, this study was undertaken to evaluate the efficacy of copper sulfate, dodine, and sulfur alone or in combination with other single-site fungicides against leaf spot diseases as chlorothalonil alternatives as well as their influence on yield. Under low disease pressure, all the alternative fungicide programs provided statistically similar leaf spot control when compared to chlorothalonil alone. In contrast, under high disease pressure in 2022, dodine alone and dodine + penthiopyrad did not significantly decrease leaf spot severity when compared to the nontreated control. Additionally, dodine alone and the 2022 premium fungicide program had significantly higher leaf spot severity when compared to chlorothalonil alone under favorable weather patterns for rapid disease development. Sulfur + copper sulfate significantly reduced leaf spot severity as compared to chlorothalonil alone only in 2022. All other remaining fungicide programs provided statistically similar control as chlorothalonil alone. Overall, dodine, sulfur, and copper sulfate have potential to serve as alternatives to chlorothalonil in leaf spot fungicide spray programs in peanuts.

Response of selected peanut commercial cultivars to leaf spot diseases as influenced by fungicide inputs

Early leaf spot (caused by Passalora arachidicola) and late leaf spot (caused by Nothopassalora personata) are the most widespread, damaging foliar diseases of peanuts in the southeastern United States. When left nontreated, both diseases can prematurely defoliate peanuts and reduce peanut yields by up to 70%. Leaf spot diseases are primarily managed through a combination of fungicide applications and cultivar selection. In this study, six field experiments were conducted from 2021 to 2022 in Brewton, Headland, and Tallassee, Alabama, to evaluate the response of ten selected commercial peanut cultivars to various levels of leaf spot pressure as influenced by low- and high-input fungicide programs when compared to nontreated controls. The low input fungicide program included seven applications of chlorothalonil, whereas the high input fungicide program comprised of fluxapyroxad, pyraclostrobin, mefentrifluconazole, flutolanil, bixafen, flutriafol, tebuconazole, and/or chlorothalonil. Effects on leaf spot and pod yields were assessed. Leaf spot severity was higher for TUFRunner™ ‘297’, Georgia-16HO, and FloRun ‘331’, but was lower for AU-NPL 17, Georgia-06G, Georgia-12Y, and Georgia-14N. In terms of yield, leaf spot tolerant varieties showcased superior performance in high disease pressure, whereas susceptible varieties excelled in low disease pressure. Fungicides significantly enhanced the performance of susceptible cultivars under high leaf spot pressure, with marginal impact in low leaf spot pressure. These results highlight the importance of selecting cultivars and fungicide spray programs based on disease pressure to maximize profits.

Farmers’ purchase intention and willingness to pay for certified sweetpotato seed under different disease pressure zones in Uganda

AbstractThe use of certified sweetpotato (Ipomoea batatas) seed (CSS) was reported to unlock the yield potential of the crop leading to an over 80% yield increase. Despite the availability of elements of a formal CSS system, uptake in Uganda has remained dismal. Interdependence between farmer knowledge, perceptions, and purchase behaviors (PBs) is not well understood in a way that could allow the design of meaningful policies and interventions. This study aimed at unveiling factors underlying PB through purchase intention (PI) and willingness to pay (WTP) by interviewing 289 farmers from Omoro and Mpigi districts in Uganda, representing the low and high virus disease pressure zones, respectively. A modified theory of planned behavior (TPB) incorporating awareness as independent and farmer innovativeness as mediating variables expounded the relationships. Data were collected on perceptions, knowledge, innovativeness, and PI using a five‐point Likert scale plus WTP as a price, subjected to descriptive and structural equation modeling analysis. Results indicated significant locational differences in most socioeconomic characteristics. Middle income, CSS information access, and farming experience of 7–30 years conferred more likelihood of high PI. Conversely, high PI, group membership, and being female and middle‐aged increased the likelihood of high WTP. The effects of attitude, perceived behavioral control, and awareness were significant in high disease zone, while subjective norm was significant across disease zones. PI significantly affects WTP in high disease zone (p = 0.000) but its effect is insignificant in low disease zone (p = 0.569). An interplay of socioeconomic, perception, and knowledge attributes influences CSS PB calling for social marketing strategies with location‐specific interventions.

Field response and molecular screening of European wheat germplasm against powdery mildew at the Himalayan region of Pakistan.

Wheat powdery mildew possesses a significant threat to wheat crops not only on a global scale but also in the northern region of Pakistan. Recognizing the need for effective measures, the exploration and utilization of exotic germplasm take on critical importance. To address this, a series of trials were made to investigate the response of 30 European (EU) lines, in addition to the local checks (Siran, Atta-Habib (AH) and Ghanimat-e-IBGE) against wheat powdery mildew at the Himalayan region of Pakistan. The study involved field testing from 2018 to 2022 across multiple locations, resulting in 38 different environments (location × year). In addition to field evaluations, molecular genotyping was also performed. The disease was absenton the tested lines during 2018, 2019, and 2020 whereas it ranged from 0 to 100% at Chitral location during 2021, where 100% was observed only for one EU wheat line "Matrix." The disease prevailed only at Gilgit location (0-60% for EU wheat line "F236") and at Nagar location (0-10% for EU wheat lines Substance and Nelson) during the disease season of 2022. Most of the EU wheat lines showed very low ACI values, due to an overall low disease pressure. Matrix showed the maximum ACI (1.54) followed by Ritter (1.25) and Bli_autrichion (0.87), whereas the minimum (0.1) was for Substance, JB_Asano, and KWS_Loft followed by Canon (0.19), all exhibiting partial resistance. The molecular marker-based screening revealed that Pm38 was the most prevalent and detected in 100% of wheat lines followed by Pm39 (60%) and Pm8 (30%). Six wheat lines (20%) possessed all three Pm genes (Pm8, Pm38, and Pm39) concurrently. The variability observed in this study can be utilized in future breeding efforts aimed at developing resistant wheat varieties.

Hybrid insect protection and fungicide application for managing ear rots and mycotoxins in silage corn

AbstractMycotoxins in silage corn (Zea mays L.) accumulate due to ear rot infections by certain ascomycete fungi and cause health issues in livestock. Fungal infections intensify with increase in ear‐damaging insect injury and favorable environment in the US Great Lakes region. Therefore, evaluating strategies such as hybrid insect protection and fungicide decisions to manage insects, ear rots, mycotoxin, and silage quality is crucial. Field trials were conducted in randomized complete block design at 11 Michigan site‐years across 2019–2021 using three hybrid insect protection levels under two levels of prothioconazole fungicide (treated and non‐treated). Hybrids (two per level) included: conventional (non‐Bt); Bt with Cry1F and Cry1Ab (BtE), protection only against European corn borer (ECB); and Bt with Cry1F and Vip3A (BtEW), protection against both ECB and western bean cutworm (WBC). Insect injury and ear rot index were 80%–90% and 75%–90% lower, respectively, in BtEW hybrids than non‐Bt hybrids. Strong correlation between insect injury and ear rot severity was observed when insect pressure was high. Mycotoxin levels, particularly deoxynivalenol (DON), was also lowest in BtEW hybrids. Weak correlations were observed between ear injury and mycotoxin concentration. Under low disease pressure, a 50%–70% reduction was observed in fungicide treated plots for both ear rot incidence and DON concentration. However, fungicide application did not reduce ear rot infections driven by high insect injury. Treatments had negligible impact on forage quality. Overall, results indicated that incorporating insect protection in hybrid selection decisions reduced insect feeding, disease occurrence, and mycotoxins, especially under high insect pressure.

Genome Sequence and Assembly of 18 Fusarium Isolates from Florida Citrus under High Huanglongbing Disease Pressure and California Citrus under Low Huanglongbing Disease Pressure

The genomes of eighteen Fusarium isolates cultured from diseased and healthy citrus trees were sequenced, assembled, and annotated. Isolate species identification was confirmed using single marker (TEF1-alpha) phylogenetic assessment. Studies of the traits and genotypes of plant-associated isolates are important to understanding the fungal contribution to phytobiomes of citrus.

Highly specific qPCR and amplicon sequencing method for detection of quarantine citrus pathogen Phyllosticta citricarpa applicable for air samples

AbstractThe fungus Phyllosticta citricarpa is a quarantine pathogen in the EU and is of high economic importance in many parts of the world where favourable climate conditions drive the development of citrus black spot (CBS) disease. Disease symptoms include necrotic lesions on leaves and fruits. Low disease pressure can reduce crop marketability, while higher disease pressure can cause premature fruit drop, significantly increasing crop losses. The wind‐dispersed spores of P. citricarpa are especially problematic for rapid pathogen dispersal, but also provide an opportunity for early detection of the disease spreading into a new area. In this study we have developed and validated a quantitative PCR (qPCR) assay based on the TEF1‐α sequence. Specificity testing demonstrated that it is currently the only qPCR assay that does not cross‐react with closely related Phyllosticta species. The assay is sensitive and can detect a single copy of the TEF1 gene in a reaction, it is highly repeatable and reproducible and can be used for testing of the sticky tapes from spore traps as well as citrus fruit samples. High‐throughput sequencing (HTS) of the DNA barcodes ITS1 and TEF1 was also explored for the detection and discrimination of P. citricarpa. The limit of detection of the HTS was 1000 spores on a daily spore trap tape. This study makes an important improvement to the diagnostics of the CBS and the methods developed can also be applied to improve the surveillance and early detection of the pathogen when linked to spore samplers in the field.

Field Studies on the Effect of Rye Cover Crop on Soybean Root Disease and Productivity

Cover crops improve soil and water quality in annual cropping systems, but knowledge of their impact on soybean ( Glycine max L.) seedling and root diseases is limited. The effects of winter rye cover crops ( Secale cereale L.) on soybean population, biomass, root morphology, seedling and root diseases, pathogen incidence, canopy reflectance, and yield were assessed over 2 years in Iowa and Missouri, U.S.A. Plots without a rye cover crop were compared with plots with early-kill rye and late-kill rye cover crops, which were terminated 34 to 49 days or 5 to 17 days before soybean planting, respectively. Soybean shoot dry weight, root rot severity, and incidence of Fusarium spp. and Pythium spp. on roots were not influenced by the treatments. Soybean grain yield and plant population were reduced in the presence of rye in 2 site years, increased in 1 site year, and unchanged in the remaining site years. Soybean canopy reflectance was measured at 810 nm, and measurements were first made at 70 to 80 days after planting (DAP). At least five measurements were obtained at 7- to 15-day intervals, ending at 120 to 125 DAP. Measurements at approximately 120 to 125 DAP differed by treatments but were not consistently associated with the presence or absence of a rye cover crop. Our field studies suggest that Iowa and Missouri soybean farmers can use winter rye as a cover crop in soybean fields with low seedling disease pressure without increasing the risk of seedling and root diseases or suppressing yield. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Spatial and Temporal Changes of Soil Microbial Communities in Field Tomato Production as Affected by Anaerobic Soil Disinfestation

Anaerobic soil disinfestation (ASD) has been demonstrated as an effective alternative to pre-plant chemical soil fumigation (CSF) commonly used to control soilborne pathogens. However, the ASD effects on spatial and temporal changes in soil microbial communities remain poorly understood in production systems with low soilborne disease pressure. The objective of this study was to assess the influence of ASD treatments on soil microbial community composition at different soil depths during the spring tomato production season in Florida. Soil treatments included ASD using 6.9 m3 ha−1 of molasses with 11 Mg ha−1 of composted poultry litter (CPL) (ASD0.5), ASD with 13.9 m3 ha−1 of molasses and 22 Mg ha−1 CPL (ASD1.0), and chemical soil fumigation (CSF) using a mixture of 1,3-dichloropropene and chloropicrin. Soil microbial community composition was measured at soil depths of 0–15 and 15–30 cm using phospholipid fatty acid (PLFA) analysis at 0, 36, 76, and 99 days after transplanting (DAT). Fatty acid methyl esters were categorized into biomarker groups including total microbial biomass (TMB), G+ bacteria (G+), G− bacteria (G−), actinomycetes (Actino), arbuscular mycorrhizal fungi (AMF), protozoa, and general fungi (F). Soil concentrations of G+, Actino, F, AMF, and the ratio of F:bacteria (B) were significantly impacted by a soil treatment × soil depth × sampling time three-way interaction. All the microbial biomarkers were significantly affected by soil treatment × sampling depth two-way interactions except for protozoa and F:B ratio. Concentrations of TMB, Actino, AMF, F, G+, and G− bacteria were significantly increased in ASD treated soils at both 0–15 and 15–30 cm soil depths across different sampling times compared with CSF. In addition, the concentrations of G+ and G− bacteria, AMF, F, and TMB were higher at 0–15 vs. 15–30 cm soil depth under ASD treatments, whereas no soil depth differences were observed in CSF. Discriminant analysis further confirmed that soil microbial community composition was distinctly different in CSF compared with ASD treatments. The soil microbial profile was well-differentiated between the two soil depths under ASD treatments but not in CSF, while the enhancement of PLFA biomarkers by ASD decreased with increasing soil depth.

Harnessing the Potential of Wheat-Pea Species Mixtures: Evaluation of Multifunctional Performance and Wheat Diversity.

Species mixtures and heterogeneous crop populations are two promising approaches for diversified ecological cropping systems with increased resilience and reduced dependency on external inputs. Inter- and intraspecific diversity were evaluated in combination using 15 wheat (Triticum aestivum) entries, including line cultivars and heterogeneous populations (HPs), from central Europe and Hungary and one winter pea cultivar under organic conditions. Monocultures and wheat mixtures were evaluated multi-functionally for yield, quality, land use efficiency, crop protection, and wheat entry traits. Mixtures increased cereal grain quality, weed suppression, resource use efficiency, yield gain, and reduced lodging. Effects were stronger in 2018/19, which were characterized by dry and nutrient-poor conditions than in 2019/20 when nutrient levels were higher. Wheat entries varied considerably in protein content and yield in both mixtures and monocultures. Under higher nutrient availability, entry-based variation was reduced in both systems, and peas were suppressed. Because of low disease pressure, the wheat entries varied little in terms of disease protection services, and mixture effects on the disease were low. The multi-criteria framework identified stability of yield, yield gains, and quality under high environmental variability of mixtures as clear agronomic advantages with HPs being considerably more stable than line cultivars. Some line cultivars outperformed the HPs in either protein content or yield across environments but not both simultaneously. Trait analysis revealed a possible link between harvest index and reduced competition in mixtures, which can increase yield performance in specific line cultivars. System cultivar interactions were generally very low and highly dependent on environmental conditions. We conclude that while cultivar breeding for mixtures can be successful in monocultures, high environmental variation highlights the necessity of evaluating cultivars in mixtures. In addition, use of intraspecific diversity within interspecific mixed cropping systems can be a valuable addition to further improve mixture performance and its stability under increasing environmental stresses due to climate change.

Effective Biocontrol of Rice Blast through Dipping Transplants and Foliar Applications

Rice (Oryza sativa) is an increasingly popular food in Africa. As much as 30% of yields are lost due to blast disease caused by Magnaporthe oryzae. Several commercial biopesticides of Bacillus subtilis, Trichoderma asperellum, and Serratia sp. strains were evaluated under field conditions for their effects against rice blast and yield at one site in Kenya and three sites in Tanzania in 2020 and 2021. Each biopesticide was applied as a dipping treatment at transplanting, post-transplanting foliar spraying, or both. Using biopesticides not only achieved blast control but also increased grain yield, particularly in low-production regions in Tanzania, with a yield increase of >100%. For higher-production sites with low disease pressure, the yield increase through biopesticides over the untreated control was limited, although significant disease suppression was achieved. Dipping alone was sufficient to suppress disease and improve yield unless disease pressure was high. The differences among the three biopesticides varied with site/year but generally were small. Improved yield using biopesticides is unlikely to result solely from reduced blast development, but also from improved plant development. The present study suggests that these commercial biopesticides should be applied in rice production, particularly in subsistence farming.

Investigating the Distribution of Strains of Erwinia amylovora and Streptomycin Resistance in Apple Orchards in New York Using Clustered Regularly Interspaced Short Palindromic Repeat Profiles: A 6-Year Follow-Up

Fire blight, caused by the bacterium Erwinia amylovora, is one of the most important diseases of apple. The antibiotic streptomycin is routinely used in the commercial apple industries of New York (NY) and New England to manage the disease. In 2002 and again, from 2011 to 2014, outbreaks of streptomycin resistance (SmR) were reported and investigated in NY. Motivated by new grower reports of control failures, we conducted a follow-up investigation of the distribution of SmR and E. amylovora strains for major apple production regions of NY over the last 6 years (2015 to 2020). Characterization of clustered regularly interspaced short palindromic repeat (CRISPR) profiles revealed that a few "cosmopolitan" strains were widely prevalent across regions, whereas many other "resident" strains were confined to one location. In addition, we uncovered novel CRISPR profile diversity in all investigated regions. SmR E. amylovora was detected only in a small area spanning two counties from 2017 to 2020 and was always associated with one CRISPR profile (41:23:38), which matched the profile of SmR E. amylovora, discovered in 2002. This suggests the original SmR E. amylovora was never fully eradicated and went undetected because of several seasons of low disease pressure in this region. Investigation of several representative isolates under controlled greenhouse conditions indicated significant differences in aggressiveness on 'Gala' apples. Potential implications of strain differences include the propensity of strains to become distributed across wide geographic regions and associated resistance management practices. Results from this work will directly influence sustainable fire blight management recommendations for commercial apple industries in NY state and other regions.

Fungicide resistance status and chemical control options for the brassica pathogen Pyrenopeziza brassicae

AbstractPyrenopeziza brassicae causes leaf spot disease of Brassicaceae in Europe/Oceania (lineage 1) and North America (lineage 2). In Europe, fungicides currently used for disease management are sterol 14α‐demethylase (CYP51) inhibitors (azoles), quinone outside inhibitors (QoIs), and succinate dehydrogenase inhibitors (SDHIs); methyl benzimidazole carbamates (MBCs) are no longer applied. In this study, in vitro screening revealed European populations (collected 2018–2020) had shifted towards decreased azole sensitivity, but the North American population (2014–2016) was highly sensitive. Genotyping revealed CYP51 substitutions G460S or S508T were prevalent in European populations, often with a CYP51 promoter insert. Compared to wildtype CYP51 isolates, those with G460S plus an insert (44/46/151/210/302 bp) were c.25–32‐fold and c.50‐fold less sensitive to tebuconazole and prochloraz, respectively; those with S508T plus an insert (44/46/151/233 bp) were c.9–15‐fold and c.25–40‐fold less sensitive to tebuconazole and prochloraz, respectively. Selection for G460S (quantified via pyrosequencing) under different fungicide regimes was investigated in UK field trials, but G460S levels were high (c.76%) before treatment, so further selection during the trials was unclear. Despite the high G460S frequency and low disease pressure, yield data indicated measurable benefit for both azole‐ and non‐azole‐based programmes. In vitro screening against the MBC carbendazim showed European populations were predominantly moderately resistant/resistant; the North American population was sensitive. European and North American populations were sensitive to QoI (pyraclostrobin) and SDHI (penthiopyrad) fungicides. Results support an azole plus QoI/SDHI mixing partner for robust disease control and decreased risk of resistance, with continued sensitivity monitoring to ensure optimal strategies are deployed.

Late Leaf Spot Defoliation, Microclimate Modification, and Southern Stem Rot Development in Peanut (Arachis hypogaea L.) in South Carolina

ABSTRACT Southern stem rot (SSR) of peanut, caused by Athelia rolfsii, is commonly influenced by environmental conditions. Defoliation from late leaf spot (LLS), caused by Nothopassalora personata, alters canopy structure and has the potential to affect microclimates. A better understanding of the potential interaction between SSR and LLS through potential microclimate modification might contribute to improved disease management. Eight field experiments were conducted from 2016 to 2019 to investigate the effect of LLS defoliation on peanut canopy and soil microclimates and SSR development. To encourage different levels of LLS defoliation, 3 spray programs (3, 4 and 6 chlorothalonil applications) were applied across four cultivars varying in susceptibility to LLS and SSR via a split-plot design. Defoliation was rated every 2 weeks from 75 days after planting (DAP) to harvest. Canopy and soil temperature and soil moisture were recorded from 75 to 140 DAP. Interaction of LLS spray program and peanut cultivar significantly affected LLS defoliation in nearly all trial years except in 2019 where low disease pressure occurred due to dry weather. Significant relationships were observed between LLS defoliation and daily maximum canopy temperatures and between area under LLS defoliation curve (AUDC) and slope of daily canopy temperature change. The influence of LLS defoliation on the microclimate was generally erratic. The relationship between AUDC and SSR was not significant. Results from this study suggest that the influence of LLS on microclimate was insufficient to substantially affect SSR development.

Host-generalist fungal pathogens of seedlings may maintain forest diversity via host-specific impacts and differential susceptibility among tree species.

Host-specialized pathogens are credited with the maintenance of tropical forest diversity under the Janzen-Connell hypothesis. Yet, in diverse forests, selection may favor pathogens with broad host ranges, given their passive dispersal and the relative rarity of tree species. We surveyed the host associations of potential pathogens isolated from symptomatic seedlings in forests in Panama and used inoculations to assess the pathogenicity and host ranges of 27 fungal isolates, and differences among tree species in susceptibility. Thirty-one of the 33 nonsingleton operational taxonomic units (OTUs) isolated from seedlings are multi-host. All 31 multi-host OTUs exhibit low to moderate specialization, and we observed phylogenetically overdispersed host use for 19 OTUs. The pathogenicity of 10 isolates was experimentally confirmed; nine caused disease in seedlings in multiple families. However, the outcome of infection differs among tree species susceptible to a given multi-host pathogen. Furthermore, some tree species were seemingly resistant to all fungi tested, while others were susceptible to multiple fungi. Tree species adapted to environments with lower disease pressure were most likely to exhibit disease. Our results suggest that generalist pathogens contribute to the maintenance of local and regional forest diversity via host-specific impacts and the exclusion of disease-sensitive trees from disease-prone habitats.

Botanical fungicides in the control of soybean leaf diseases / Fungicidas botânicos no controle de doenças foliares na soja

The soybean cultivation (Glycine max (L.) Merrill) is responsible for the highest pesticides use in agriculture in Brazil. There is an environmental and social need to reduce the use of these substances in crops. The alternative products applied in agriculture such as plant extracts and essential oils, becomes necessary and indispensable, mainly in disease control. Among the plants studied, the Noni (Morinda citrifolia L.), has stood out in some studies, where relevant fungitoxic results have been demonstrated, however, there are still few works that prove its viability in the diseases management in field. Thus, this work aimed to evaluate the soybean diseases alternative control through the aqueous extracts and noni essential oil application, in plantings high and low disease pressure. Two field experiments were implemented, with soybean culture, evaluating leaf, fruit aqueous extract and noni essential oil as a fungicidal action. Foliar application of noni extracts and essential oil did not differ from fungicide in Asian Rust and Anthracnose control, in the 2016/17 crop, in both experiments. Soybean productivity was similar in treatments that received leaf extract (1748,8 Kg ha-1), essential oil (1762,5 Kg ha-1) and fungicides (2031,7 Kg ha-1). Where there was no large disease pressure all agronomic characteristics were equivalent, regardless of treatment.

Autonomous UV-C application to deal with low and high powdery mildew disease pressure in strawberry

Autonomous UV-C application to deal with low and high powdery mildew disease pressure in strawberry

Traffic form and season of wear affect responses of fine fescues

AbstractThe performance of fine fescue (Festuca spp.) species and cultivars may differ by traffic form or the season of wear simulation. Two trials were initiated in 2012 to evaluate the effect of traffic form (abrasive wear vs. cleated traffic) and season of wear (spring, summer, or autumn) on 10 fine fescues seeded in North Brunswick, NJ. Plots were visually assessed for the fullness of turfgrass canopy (FTC) and leaf bruising. Verdure and soil physical properties were assessed after the last assessment period in the traffic form trial. Abrasive wear constantly reduced the FTC (14–30%) of fine fescues compare to the non‐trafficked control, while the FTC of plots with cleated traffic was similar to the non‐trafficked control towards the end of the study. Although both traffic forms caused soil compaction, cleated traffic resulted in a more compacted soil. Abrasive wear improved selection efficiency for fine fescues compared to cleated traffic. The FTC response of fine fescues cultivars interacted with the season of wear; thus, screening for fine fescues with improved ability to withstand abrasive wear might be more effective and accurate during spring to avoid high disease pressure and other confounding stresses during summer. ‘Blueray’ and ‘Beacon’ hard fescue, ‘Quatro’ sheep fescue, and ‘Radar’ Chewings were more traffic tolerant than other fine fescue cultivars under low disease pressure. The propensity of fine fescues to bruising under wear needs to be assessed in both summer and autumn.

Comparative Efficacy of Different Chemical Fungicide Groups against Cotton Root Rot

The current study was undertaken to evaluate the influence of various fungicidal treatment on the inhibition percent of pathogens and as seed treatment on cotton seedling stand establishment against root rot of cotton in in vitro as well as in field conditions at Sakha Agriculture Research Station during two seasons 2019 and 2020. This study was carried out to evaluate once more available fungicides, for their effectiveness against the root rot pathogens (Rhizoctonia solani ,Fusarium oxysporum and Macrophomina phaseolina). And upon it evaluate which of them for used it as seed treatment. All tested fungicides exhibited reduction in the radial growth of mycelium for all the testing fungi significantly compare with control. Hymexazole and Tebuconazole + fludioxnile showed excessive decreased of mycelial growth, when Hymexazole; Tebuconazole + fludioxnile; Carboxin + thiram; Triticonazole and Fludioxanile + mefenoxam (metalaxyl-m) gave best results in the reduction percent of inhibition) for the three tested pathogens. Efficiency of fungicide seed treatments were expressed as increased in standing percent; plant height and dry weight of plant. Disease incidence was very low in both Propanocarb HCl + fostyl Al and Fludioxanile + mefenoxam (metalaxyl-m). Generally, the fungicide treatments ended a little or no difference in plant height or dry weight. Under the field conditions (low disease pressure), results indicated that, fungicide seed treatments are slightly effective in increasing standing percent. Diniconazole-M was the most effective in disease reduction (expressed as 100% standing percent). These treatments were translated into increased plant height and dry weight of plants.

Genetic variation for fusarium crown rot tolerance in durum wheat.

Tolerance to the cereal disease Fusarium crown rot (FCR) was investigated in a set of 34 durum wheat genotypes, with Suntop, (bread wheat) and EGA Bellaroi (durum) as tolerant and intolerant controls, in a series of replicated field trials over four years with inoculated (FCR-i) and non-inoculated (FCR-n) plots of the genotypes. The genotypes included conventional durum lines and lines derived from crossing durum with 2-49, a bread wheat genotype with the highest level of partial resistance to FCR. A split plot trial design was chosen to optimize the efficiency for the prediction of FCR tolerance for each genotype. A multi-environment trial (MET) analysis was undertaken which indicated that there was good repeatability of FCR tolerance across years. Based on an FCR tolerance index, Suntop was the most tolerant genotype and EGA Bellaroi was very intolerant, but some durum wheats had FCR tolerance indices which were comparable to Suntop. These included some conventional durum genotypes, V101030, TD1702, V11TD013*3X-63 and DBA Bindaroi, as well as genotypes from crosses with 2-49 (V114916 and V114942). The correlation between FCR tolerance and FCR-n yield predictions was moderately negative indicating it could be somewhat difficult to develop FCR-tolerant genotypes that are high yielding under low disease pressure. However, FCR tolerance showed a positive correlation with FCR-i yield predictions in seasons of high disease expression indicating it could be possible to screen for FCR tolerance using only FCR-i treatments. These results are the first demonstration of genetic diversity in durum germplasm for FCR tolerance and they provide a basis for breeding for this trait.