Late Blight Development Research Articles

Impact of biopreparations on the phytopathological state of potato plants

Given the frequent use of chemical agents for the control of potato diseases, it is crucial to explore protective measures that consider agroecological aspects. This study aimed to determine the impact of biological preparations on the development of late blight and alternariosis in potatoes. Research on the effects of biopreparations on the main diseases of potatoes was conducted over three years under field conditions at the Volyn State Agricultural Research Station of the Institute of Potato Growing of the National Academy of Agrarian Sciences of Ukraine. The experimental design, disease diagnosis, and assessment of the technical efficacy of biological preparations against potato diseases were performed according to established methodologies. The experiments revealed that the application of biopreparations under various conditions leads to a reduction in the intensity of late blight and alternariosis in potatoes, as well as contributing to the preservation of yield. Lower disease development and higher efficacy of biopreparations were observed in the context where the biodestructor Ekostern (1.2 L/ha) and the biopreparation MycoHelp (2.0 L/ha) were applied, alongside three rounds of plant spraying with various biological preparations – Agat-25K, Regoplant, PhytoHelp, and Stimpo. Among these, PhytoHelp, with an application rate of 1.0 L/ha, exhibited the highest technical efficacy. The use of biological preparations in different contexts increased potato tuber yield. Specifically, with the application of MycoHelp at 2.0 L/ha and the spraying of plants with various biological agents, the preserved yield ranged from 1.71 to 2.02 t/ha. The application of biopreparations alongside the use of Ekostern at 1.2 L/ha and MycoHelp at 2.0 L/ha contributed to yield increases across various treatments, ranging from 1.6 to 2.21 t/ha. The obtained results are deemed useful for enhancing the effectiveness of the integrated protection system for potatoes against specific diseases and for developing organic cultivation technologies for table potatoes on sod-podzolic soils

Impact of biopreparations on the phytopathological state of potato plants

Given the frequent use of chemical agents for the control of potato diseases, it is crucial to explore protective measures that consider agroecological aspects. This study aimed to determine the impact of biological preparations on the development of late blight and alternariosis in potatoes. Research on the effects of biopreparations on the main diseases of potatoes was conducted over three years under field conditions at the Volyn State Agricultural Research Station of the Institute of Potato Growing of the National Academy of Agrarian Sciences of Ukraine. The experimental design, disease diagnosis, and assessment of the technical efficacy of biological preparations against potato diseases were performed according to established methodologies. The experiments revealed that the application of biopreparations under various conditions leads to a reduction in the intensity of late blight and alternariosis in potatoes, as well as contributing to the preservation of yield. Lower disease development and higher efficacy of biopreparations were observed in the context where the biodestructor Ekostern (1.2 L/ha) and the biopreparation MycoHelp (2.0 L/ha) were applied, alongside three rounds of plant spraying with various biological preparations – Agat-25K, Regoplant, PhytoHelp, and Stimpo. Among these, PhytoHelp, with an application rate of 1.0 L/ha, exhibited the highest technical efficacy. The use of biological preparations in different contexts increased potato tuber yield. Specifically, with the application of MycoHelp at 2.0 L/ha and the spraying of plants with various biological agents, the preserved yield ranged from 1.71 to 2.02 t/ha. The application of biopreparations alongside the use of Ekostern at 1.2 L/ha and MycoHelp at 2.0 L/ha contributed to yield increases across various treatments, ranging from 1.6 to 2.21 t/ha. The obtained results are deemed useful for enhancing the effectiveness of the integrated protection system for potatoes against specific diseases and for developing organic cultivation technologies for table potatoes on sod-podzolic soils

Changes in the content of carotenoids in potato tubers cultivated with or without the application of fungicides

AbstractIn this study, three cultivars and seven tetraploid potato clones were evaluated for two years in two cultivation systems (CS): without chemical protection against late blight development (NP) and with chemical protection (P). The objective of this study was to quantify the effect of chemical protection on the level of total carotenoids (TC) and individual carotenoids in potato tubers. The presented study showed that the content of TC in potato tubers is significantly affected by the CS and genotype. TC were higher in the system NP (mean 329.6 µg/100 g fresh weight [FW]) than in the system P (mean 206.2 µg/100 g FW). Although the development of late blight was observed only in the year 2019, a higher content of TC was observed in the system NP in both years. This dependence clearly show that CS without chemical protection favor carotenoids accumulation in potatotubers. In the case of lutein, the year had a significant impact on the concentration. The concentration of lutein in 2018 for the majority genotypes was higher (mean 72.1 µg/100 g FW), than in year 2019 (mean 37.3 µg/100 g FW), when late blight development wasobserved. The sharp decrease in lutein content in 2019 was probably caused by the development of late blight. A significant decrease of lutein content in potato tubers was observed in 2019 for all genotypes in system P and for five genotypes in system NP. It can be assumed that resistance mechanisms that occur during infection may have disturbed the accumulation of lutein in potato tubers.

Chemical protection of potatoes from fungal diseases, taking into account the stability of the variety

In the conditions of the Moscow region in 2019-2022 the effectiveness of funicides of new chemical classes in the potato protection system against rhizoctoniosis, late blight and alternariosis was studied, taking into account the different resistance of varieties (Gulliver, Grant, Sante) to diseases. Potato tubers were treated with the preparation Idikum, SC before planting, its biological effectiveness in reducing the incidence of rhizoctoniosis in the full germination phase was 76.7-95.7 %. It was found that the effectiveness of the preparation depended on the degree of disease development, the stability of the variety and the phase of crop development. In addition, when etching the planting material with Idikum, SC, there was no population of rhizoctosis sclerotia and the spread of dry rot on tubers of the new yield significantly reduced (1.6-5.0 times) compared to the control. The proposed scheme of potato protection in conditions of epiphytotic development of late blight and early blight based on combined chemicals Metaxil, SP, Inside, SC with contact fungicides Raek, CE, Talent, SC, Tirada, SC showed high efficiency in reducing harmfulness of the diseases, which allowed to extend the growing season of plants, to ensure a higher yield of potatoes, its marketability and quality. The use of preparations provided an increase in yield by 36.3-47.5 %, depending on the prevailing weather conditions of the growing season and on the variety in relation to the control (without treatment). It has been established that the biological effectiveness of the protection scheme in reducing the degree of late blight and early blight increased from susceptible to relatively stable varieties and, accordingly, this trend continued with an increase in yield. Higher increases were obtained on unstable varieties Gulliver and Sante (10.6-13.5 t /ha, or 45.7-56.0 %), lower – on the relatively stable variety Grand (7.8 t/ha, or 36.0 %). The contribution of the application of the protection scheme to the overall variation of gross and marketable potato yields was 76.5-81.0 %, gene-type - 7.9-12.5 %, the interaction of these factors – 3.7-4.7 %.

Agroecological еще testing of за promising potato до varieties of кто domestic selection он in the бы conditions of при the North что Caucasus region они

The studies evaluated 60 potato varieties of different maturation groups of domestic breeding in terms of productivity, quality indicators and immunity to various types of diseases. Varieties with high productivity potential and the most adaptive to the soil and climatic conditions of the North Caucasus region were identified. In the course of the research work, the following tasks were solved:
 According to the results of testing potato varieties in the conditions of the North Caucasus region, the most plastic varieties of domestic originators were identified, characterized by high yield indicators in relation to standard varieties. The yield level of more than 40 t/ ha exceeded the early varieties Meteor, Leader, Mayak, Sadon, Real. The high marketability of tubers was formed by early and mid-early varieties: Gulliver (93%), Warmas (92%), Sineglazka (92%), Samba (93%), Lukyanovsky (91%). The manifestation of macrosporiosis, on average for three years, ranged from 1.7 to 12.0%. During the growing season, the manifestation of alternariosis was up to 3.3%, the active development of late blight reached up to 50%. The most common of the viral diseases were mottled and wrinkled mosaics.

The influence of various pesticide loads on the development of late blight and potato alternariоsis in the Central region of Russia

Field experiments were conducted to test three schemes for the use of drugs of different action spectra in order to reduce the chemical load on the potato biocenosis. The experiments were carried out on four varieties differing in resistance to late blight. According to the results of two-year tests, it was revealed that on resistant varieties Grand, Kumach and medium-resistant varieties Gulliver, even in epiphytotic years for late blight, it is possible to use alternating preparations, which reduces the chemical load by 33.3%. On the Northern Lights variety unstable to late blight, only a chemical scheme can be used in such years. In the years with the depressive development of late blight, the use of any schemes was not very effective. Etching of planting tubers with Edikum preparation in some years reduces the germination of Grand and Gulliver varieties by 90-70%, Kumach and Northern Lights varieties by 13-16%, which negatively affects potato yields.

Screening South American Potato Landraces and Potato Wild Relatives for Novel Sources of Late Blight Resistance.

Late blight (LB) caused by the oomycete Phytophthora infestans is one of the most important biotic constraints for potato production worldwide. This study assessed 508 accessions (79 wild potato species and 429 landraces from a cultivated core collection) held at the International Potato Center genebank for resistance to LB. One P. infestans isolate belonging to the EC-1 lineage, which is currently the predominant type of P. infestans in Peru, Ecuador, and Colombia, was used in whole plant assays under greenhouse conditions. Novel sources of resistance to LB were found in accessions of Solanum albornozii, S. andreanum, S. lesteri, S. longiconicum, S. morelliforme, S. stenophyllidium, S. mochiquense, S. cajamarquense, and S. huancabambense. All of these species are endemic to South America and thus could provide novel sources of resistance for potato breeding programs. We found that the level of resistance to LB in wild species and potato landraces cannot be predicted from altitude and bioclimatic variables of the locations where the accessions were collected. The high percentage (73%) of potato landraces susceptible to LB in our study suggests the importance of implementing disease control measures, including planting susceptible genotypes in less humid areas and seasons or switching to genotypes identified as resistant. In addition, this study points out a high risk of genetic erosion in potato biodiversity at high altitudes of the Andes due to susceptibility to LB in the native landraces, which has been exacerbated by climatic change that favors the development of LB in those regions.[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.

Combination of Potassium Phosphite and Reduced Doses of Fungicides Encourages Protection against Phytophthora infestans in Potatoes

Late blight caused by the oomycete Phytophthora infestans is considered the biggest threat to potato farming worldwide. For susceptible cultivars, the disease is often managed by frequent applications of fungicides to reduce yield loss. The use of bio-based compounds that interfere with biologically active systems is an innovative strategy for improving disease management. In the present work, the control of P. infestans infection on potatoes by potassium phosphite (KPhi) combined with recommended and reduced doses of active ingredients (Ais) from different fungicides was evaluated. The protective effects of different combinations were initially assessed in vivo and subsequently compared with a greenhouse screening. The active ingredients cyazofamid (CFD) and mancozeb (MCB), used at recommended and reduced doses, were less effective at reducing P. infestans infections than when combined with KPhi. In greenhouse trials, CFD, mandipropamid (MPD) and MCB at recommended doses were the most effective treatments when combined with KPhi; meanwhile, the combination of KPhi with azoxystrobin (AZ), benthiavalicarb-isopropyl/mancozeb (ISO/MCB), and CFD at reduced doses exhibited strong protective activity compared to other similar combinations. This decreased the severity of infection by P. infestans up to ~89%. Greenhouse experiments also demonstrated that a combination of KPhi and CFD at both doses caused the highest reduction in disease severity (up to ~90%) within 35 days of infection. In microplot experiments, KPhi delayed the progression of late blight in susceptible potato varieties; therefore, in the combined treatments AUDPC values were significantly lower than those obtained after applications with CFD doses, providing sufficient protection against late blight. Our data suggest that optimizing the formulation with addition of KPhi could result in a lower recommended dose. This would result in a reduction of the active compounds of the fungicides in potato farming. Furthermore, the impact of KPhi on late blight development makes it a potential component for incorporation into an integrated pest management system.

Forecasting of Potato Late Blight Disease Using Alternative Sets of Meteorological Data and Disease Epidemiyology

Phytophthora infestans (Mont) de Bary, the causal agent of late blight of potato is one of the most important plant pathogens. The disease can occur in a wide variety of weather conditions and can be very devastating if no controlled. To reduce yield losses, different protective measures are used, including fungicide treatment. Uncontrolled and numerous fungicide applications cause environmental pollution. Accordingly, crop protection strategies optimizing the number of treatments are of great interest. Prediction of potato late blight epidemics, was studied in two different locations of Adana. Meteorological data (hourly) were recorded by an iMETOS® automatic weather station installed in the field and were compared with regional station Winstel, Blite Cast and Ullrich Schrodter models. Three disease warning models were compared to forecast the development of potato late blight in Adana between 2013 and 2014 first time. In the Çukurova region, the Winstel model yielded more accurate results in predicting infection conditions compared to the other two models. Studies provided that, the conditions of potato late blight disease formation in the region were determined and the use of the Winstel early warning system in accordance with the regional conditions and biotechnical methods which will be alternative to chemical control were provided by the regional farmers.

Biocontrol Potential of Aspergillus Species Producing Antimicrobial Metabolites.

Microbial metabolites have been recognized as an important source for the discovery of new antifungal agents because of their diverse chemical structures with novel modes of action. In the course of our screening for new antifungal agents from microbes, we found that culture filtrates of two fungal species Aspergillus candidus SFC20200425-M11 and Aspergillus montenegroi SFC20200425-M27 have the potentials to reduce the development of fungal plant diseases such as tomato late blight and wheat leaf rust. From these two Aspergillus spp., we isolated a total of seven active compounds, including two new compounds (4 and 6), and identified their chemical structures based on the NMR spectral analyses: sphaeropsidin A (1), (R)-formosusin A (2), (R)-variotin (3), candidusin (4), asperlin (5), montenegrol (6), and protulactone A (7). Based on the results of the in vitro bioassays of 11 plant pathogenic fungi and bacteria, sphaeropsidin A (1), (R)-formosusin A (2), (R)-variotin (3), and asperlin (5) exhibited a wide range of antimicrobial activity. Furthermore, when plants were treated with sphaeropsidin A (1) and (R)-formosusin A (2) at a concentration of 500 μg/ml, sphaeropsidin A (1) exhibited an efficacy disease control value of 96 and 90% compared to non-treated control against tomato late blight and wheat leaf rust, and (R)-formosusin A (2) strongly reduced the development of tomato gray mold by 82%. Asperlin (5) at a concentration of 500 μg/ml effectively controlled the development of tomato late blight and wheat leaf rust with a disease control value of 95%. Given that culture filtrates and active compounds derived from two Aspergillus spp. exhibited disease control efficacies, our results suggest that the Aspergillus-produced antifungal compounds could be useful for the development of new natural fungicides.

Фитопатологическая экспертиза сортов картофеля в условиях Московской области

Abstract. The aim of the work is to conduct a phytopathological assessment of new domestic potato varieties in the conditions of the Central Region and to identify among them samples that are characterized by a high stable level of resistance to diseases. Methods. The research was carried out at the experimental base “Korenevo” in the Moscow region in 2019–2020. The soil is sod-podzolic sandy loam. The SCC of the growing seasons in 2019 is 1.39 (wet) and in 2020 2.1 (wet). The object of research is 45 varieties of domestic selection from different scientific institutions. All counts were carried out in accordance with standard methods on a natural infectious background. Results. The agrometeological conditions of the growing seasons of 2019 and 2020 contributed to the development of late blight and were satisfactory for the defeat of potato tops by alternariasis. The prevalence of rhizoctoniosis was different – moderate-depressive in 2019 and high in 2020. The lowest incidence over these years was noted only in the Morning variety-1 % (viral diseases). Potato varieties without symptoms of plant damage by rhizoctoniosis – Merchant and Morning, wrinkled mosaic – 19 varieties (41.3 %), twisting of leaves – 32 varieties (69.6 %) were identified. 33 (73.3 %) cultivars showed high resistance (8–9 points) to late blight, and 13 (28.9 %) to alternariasis. The varieties Kupets, Mariinskiy, Prizer, Tret’yakovka, Alyaska, Brusnichka, Kumach, Plamya, Signal, and Utro were distinguished by their complex resistance to these diseases. The autumn tuberous analysis showed that in 21 varieties (46.7 %) tubers were not affected by rhizoctoniosis, 28 (62.2 %) – scab, 11 (24.4 %) – wet rot. On the varieties of Lingonberry, Northern Lights, Signal and Sokur and on the hybrid G-6-14-11 no tubers with defects were found. Scientific novelty. A comprehensive phytopathological assessment of new domestic potato varieties in relation to the conditions of the Moscow region was carried out and samples with plant and tuber resistance to major diseases were identified.

Effect of Botanical Extracts on Late Blight (Phytopthora infestans) and Productivity of Tomato (Solanum esculentum)

Late blight is caused by Phytopthora infestans (Mont.) de Bary which establishes quickly in Solanum esculentum L. (tomato); as a result, it makes the pathogen one of the most devastating plant diseases across the world. The control of late blight is difficult because P. infestans has advanced and complex enzymes and effecter molecules coded by avirulence genes. As such, a study was carried out at the University of Zimbabwe, Department of Plant Production Sciences and Technologies, between August 2018 and May 2019 to evaluate the efficacy of Moringa oleifera Lour. (moringa), Eucalyptus nigra R.T. Baker (gumtree), and Lantana camara L. (sensu lato) (lantana) extracts as biofungicides on late blight development on S. esculentum. The effect of acetone, ethyl acetate, and water extracts of M. oleifera, E. nigra, and L. camara on percent inhibition and radial growth were evaluated in the laboratory. In addition, the efficacy of different extract concentrations of M. oleifera, E. nigra, and L. camara L. on defence enzymes, disease incidence, disease severity, and yield parameters of S. esculentum were assessed in the in vivo experiment. Increasing concentration of the botanical extracts significantly ( p ≤ 0.05 ) reduced radial growth and increased percent inhibition of P. infestans. In addition, increasing botanical extract concentration significantly ( p ≤ 0.05 ) increased peroxidase (PОD), phenylalanine ammonia lyse (PAL), and polyphenol oxidase (PPO) activity. Disease incidence and severity were significantly ( p ≤ 0.05 ) reduced as the concentration of the botanical extracts increased. Similarly, marketable and total yield significantly ( p ≤ 0.05 ) increased with increase in the botanical extract concentration. Gas chromatography mass spectrometry (GCMS) revealed the presence of furfural, 5-methyl-4- (trifluoromethyl) pyrido, dodecanamide, cyclopentasiloxane, and decamethyl. From the research, it can be concluded that M. oleifera ethyl acetate, E. nigra ethyl acetate, and L. camara water extracts contain antifungal compounds and can be used as biofungicides in late blight management.

English

This study aimed to screen myxobacteria strains with strong activity against Phytophthora infestans and to study its secondary metabolites. Myxobacteria were isolatedfrom a soil sample using the rabbit feces as bait. A strain inhibitive to P. infestanswas identified by morphological observation and 16S rRNA sequence analysis. The fermentation parameters were optimized through a combination of univariate analysis and orthogonal optimization. The stability and antimicrobialactivities of the secondary metabolites were determined using the filter paper method, and the effects on the development of the potato late blight and its pathogen were determined using the in vitroleaf method. The myxobacteria B25-I-1 isolated from a soil sample showed strong activity against P. infestansand was identified as Myxococcus xanthus. The optimal fermentation conditions of M. xanthusB25-I-1 were as follows: inoculum size of 10%, shaking at 180 rmin-1, incubation temperature of 32°C, and incubation time of 8 days. The secondary metabolites were highly tolerant to high temperature, treatment with protease K, andultraviolet and natural lights. Besides P. infestans, the secondary metabolites also showed variant antagonistic effects againstEscherichia coli,Staphylococcus aureus,Bacillus subtilis,Saccharomyces cerevisiae,Fusarium oxysporum, Rhizoctonia solani, and Sclerotinia sclerotiorum. The results of the potato late blight control on potato leaves indicated that the secondary metabolites could significantly inhibit the infection of detached potato leaves caused by P. infestansand caused no damage to the leaves of different varieties of potatoes by themselves. This study provides basic data for the the development of a biopesticide against potato late blight.© 2021 Friends Science Publishers

In Vitro and In Vivo Antifungal Activity of Sorbicillinoids Produced by Trichoderma longibrachiatum.

In the search for antifungal agents from marine resources, we recently found that the culture filtrate of Trichoderma longibrachiatum SFC100166 effectively suppressed the development of tomato gray mold, rice blast, and tomato late blight. The culture filtrate was then successively extracted with ethyl acetate and n-butanol to identify the fungicidal metabolites. Consequently, a new compound, spirosorbicillinol D (1), and a new natural compound, 2′,3′-dihydro-epoxysorbicillinol (2), together with 11 known compounds (3–13), were obtained from the solvent extracts. The chemical structures were determined by spectroscopic analyses and comparison with literature values. The results of the in vitro antifungal assay showed that of the tested fungal pathogens, Phytophthora infestans was the fungus most sensitive to the isolated compounds, with MIC values ranging from 6.3 to 400 µg/mL, except for trichotetronine (9) and trichodimerol (10). When tomato plants were treated with the representative compounds (4, 6, 7, and 11), bisvertinolone (6) strongly reduced the development of tomato late blight disease compared to the untreated control. Taken together, our results revealed that the culture filtrate of T. longibrachiatum SFC100166 and its metabolites could be useful sources for the development of new natural agents to control late blight caused by P. infestans.

Antagonistic Activity of Bacillus velezensis SDTB038 against Phytophthora infestans in Potato.

Potato late blight is a severe and highly epidemic disease caused by Phytophthora infestans that can affect all parts of the plant. This study mainly screened antagonistic strains for good control of potato late blight and identified strain SDTB038 as Bacillus velezensis according to its morphological and chemical properties and the 16S rRNA, gyrA, and gyrB gene sequences. This antagonistic strain achieved good control of potato late blight in greenhouses and fields and promoted potato plant growth. Two-year field trials (2018 and 2019) showed that B. velezensis SDTB038 can be used to reduce food losses caused by late blight, achieving late blight reductions of 40.79% (2018) and 37.67% (2019). In two-year field trials, the control effects of the highest concentrations of fluopimomide and B. velezensis SDTB038 were better than those of the other treatments. The control effect of 85 g ha-1 fluopimomide and B. velezensis SDTB038 and that of 170 g ha-1 fluopimomide alone showed no significant differences. These field results indicate that a low concentration of fungicide and a high concentration of SDTB038 can be effective in controlling potato late blight. Foliar detection showed that lipopeptides have an inhibitory effect on P. infestans. The amplification of lipopeptide genes revealed surfactin (srfAB and srfAC) and fengycin (fenB) genes in SDTB038, but only surfactin production by B. velezensis SDTB038 was observed by ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry analysis. Therefore, the strain B. velezensis SDTB038 can produce secondary metabolites that help potato plants resist late blight development, can effectively inhibit the infection of potato leaves by P. infestans, and has potential value for development as a biological pesticide against potato late blight.

Spectral characteristics of reflection of waves in the optical range of healthy and diseased potato plants by Y-virus and late blight

The research and analysis of the obtained measurements of the spectral reflectivity in the optical range of healthy and diseased potato plants affected by the Y-virus and late blight in laboratory conditions for the development of remote methods for collecting information on the phytosanitary state of seed and ware potatoes were carried out. Differences in the spectral characteristics of the reflection of the electromagnetic radiation of healthy and diseased potato plants in the optical wavelength range of 300-1100 nm were revealed, allowing to identify the presence of viral damage to potato plants and the development of late blight.

Use of digital technologies for potato protection

Late blight is the most devastating disease of potato, the control of which provides for the use of fungicides. To reduce the volumes of chemical treatments, the risk of late blight outbreaks and the level of corresponding yield losses should be adequately evaluated. Using the earlier developed mathematic simulator and retrospective data obtained from 415 weather stations for the last 15 years, a map was constructed reflecting the potential risk of such losses in Russia. The area of a zone with high average annual yield losses (>20%, red zone) occupies 41.3% of the total studied area, while zones with moderate (yellow zone) and low (< 10%, green zone) yield losses occupy 43.7 and 15.0%, respectively. Additionally, a geoinformation system for assessment and mapping of risks of the late blight outbreaks in a real-time mode has been developed and introduced as a part of the meteorological service of the Infometeoservice company available at http:// infometeos.com/Map/Data/. The data on the current risk levels can be used by potato-growers to make decision in relation to crop protection activities. The geosystem can be used to monitor the late blight development and to determine the optimum terms of protective treatments of potato during a vegetation season.

POTATO PRODUCTION PRACTICES AND LATE BLIGHT MANAGEMENT IN NYANDARUA COUNTY, KENYA

Potato is the second most important crop after maize for food and nutrition security in Kenya. Late blight is a major threat to potato production causing losses of up to 100% if not controlled. Poor production and disease management practices enhance the development and occurrence of potato late blight. A survey was conducted in Nyandarua County to assess potato production and disease management practices on the development and occurrence of late blight. Solvin’s formula was used to determine the sample of 105 farmers. Data on socio-demographic aspects, prevalent potato diseases, management options, and agronomic practices were collected and analyzed using SPSS version 25. Major findings reflected a positive correlation (r = 0.57, n = 105, p = 0.001) between the size of farms owned and the area under potato. Awareness of biological control practices and integrated disease management was 33.3% and 28.6%, respectively.&nbsp; Practices largely influencing disease prevalence included the use of single variety (86.7%) and farm-saved seeds (74.3%), providing a medium for inoculum incubation. Averagely, 48.6% of farmers practice mono-cropping, and 13.3% leave plant debris in the field which enhances inoculum build-up and recurrence. An average of 65.8% use fungicides in a single class, leading to the pathogen developing resistance. It is therefore recommended that potato farmers adhere to good agricultural practices including crop rotation, intercropping, alternation of fungicide classes, use of biological control products, use of clean certified seeds, proper field sanitation, and primarily Integrated Disease Management to minimize the prevalence of late blight and the associated heavy use of chemical pesticides.

Quantifying the Contribution to Virulence of Phytophthora infestans Effectors in Potato.

Late blight in potato, caused by the oomycete Phytophthora infestans, is a devastating disease that significantly impacts potato production. For a proper understanding of disease development, it is important to understand the interaction between plant and pathogen at a molecular level. Like other pathogens, P. infestans secretes effector molecules, which can be recognized by receptors in the plant and trigger immunity. In addition, effectors from P. infestans have been identified to enhance disease development. Here, we describe an assay to investigate the role of effectors in virulence of P. infestans on potato. We combine agroinfiltration to transiently express effectors in potato with detached leaf assays to monitor disease development. This protocol makes it possible to conveniently quantify the effect of individual effectors on virulence of P. infestans. The identification of effectors with an important role in late blight development can help to design better strategies to control the disease.

Economic effectiveness of using fungicides in the protection of potato against Phytophthora infestans and Alternaria spp.

The aim of the research carried out in 2014–2016 at the Plant Breeding and Acclimatization Institute in Jadwisin was to assess the economic effectiveness of the use of fungicides in combating the causative agents of potato blight and alternaria on plants of four edible potato varieties with different resistance to Phytophthora infestans. The experiment included two objects: control – without chemical protection and protection – in which from 3 to 5 chemical treatments were performed. In the protected object obtained increase of yield of tubers was 20.4%. The value of saved production amounted to an average of 4.181.8 zł/ha. In the years of research in which meteorological conditions favored the development of late blight and alternaria, high profitability of using fungicides was found. Orientation index of profitability (E2) was in the range of 2.5–4.0, which means that the performed plant protection treatment constituted from 2.5 to 4.0% of the value of the obtained tuber yield per 1 hectare.