Verticillium dahliae
Kleb., the causal agent of Verticillium wilts, is a devastating plant disease affecting many plant species. Fungus
V. dahliae
was detected in a partially artificially established
...Acer pseudoplatanus
L. forest stand in central Slovenia. This finding incited further study about the risk of different sources of
V. dahliae
isolates for maples in forests and the pathogenicity of three
V. dahliae
isolates of different origins was tested on saplings of
A. pseudoplatanus
,
A. platanoides
L., and
A. campestre
L. The inoculated saplings exhibited disease symptoms, i.e., leaf necrosis and wilting. At the end of the pathogenicity test, typical xylem browning was visible on the cross-sections, and the pathogen was successfully re-isolated. The isolates showed significant differences in their pathogenicity to specific maple hosts, with the agricultural isolate (originated from bell pepper) being the most aggressive on all three maple species. The disease severity index (DSI) and relative area under the disease progress curve (rAUDPC), as well as the success of re-isolation, indicate that
A. platanoides
is the most susceptible to inoculation with
V. dahliae
. In addition, significant differences in sapling biomass were observed between treated and control plants. These results suggest that maples in forest stands are threatened by
V. dahliae
, and biosecurity measures should be considered and implemented in forest management to reduce the transmission and potential spread of the pathogen.
Spot blotch of wheat caused by Bipolaris sorokiniana is a problematic biotic constraint that causes 15-80% yield abatement in the Indian subcontinent and other parts of the world. The most effective ...means of managing crop diseases is to develop resistant varieties against crop diseases. 25 wheat genotypes were evaluated against spot blotch (Bipolaris sorokiniana) under natural epiphytotic conditions sown on two dates (26 November and 18 December) at Rampur, Chitwan from November 2015 to April 2016. The experiment was laid out in a split plot design with three replications where dates of sowing were taken as the main plot and wheat genotypes were taken as sub-plots. Genotypes RR-21 and Morocco were taken as a susceptible check. Disease scoring for both sowing date was done 3 times at an interval of seven days. Disease severity and Area Under Disease Progressive Curve (AUDPC) were calculated. Among the tested genotypes, disease severity and AUDPC values varied significantly for both the normal and late sowing dates. The six genotypes were found resistant and eight genotypes were found moderately resistant under normal sowing conditions. None of the genotypes were found to be resistant and moderately resistant under late sowing conditions. This indicates that timely sowing of wheat is important for reducing yield loss caused by spot blotch disease irrespective of wheat genotypes grown. Seed infection percent for normal sowing was lower (25 to 85 percent) than late sowing (31 to 91 percent). This concluded that if farmers have to use the seed for sowing from their own field they should use the seeds harvested from the normal sowing date. The genotypes BL-4350, BL-4463, NL-1094, Aditya, BL-4316 and NL-971 were found resistant to spot blotch under normal sown condition. These genotypes could be used as donor parents for spot blotch resistance in breeding program or could be released as a variety after evaluating the agronomical traits and quality parameters. Fundam Appl Agric 2020; 5(3.000): 383-392
Kumi F, Badji A, Mwila N, Odong T, Ochwo-Ssemakula M, Tusiime G, Gibson P, Biruma M, Prom KL, Cuevas HE, Agbahoungba S, Rubaihayo P. 2019. New sources of sorghum resistant genotypes to downy mildew ...disease in Uganda. Biodiversitas 20: 3391-3397. Sorghum downy mildew (SDM) disease is still prevalent in Uganda at varying levels of incidence and severity. In this study, a total of 100 sorghum genotypes, five (5) from (U.SA, India, and Sudan) and 95 genotypes from Uganda were evaluated for resistance to downy mildew and other agronomic traits during the second growing season of 2016 (August-December). The experiment was conducted in two locations at Makerere University Agricultural Research Institute at Kabanyolo (MUARIK) and Abi-Zonal Agricultural Research and Development Institute (Abi-ZARDI) research station at Arua. The experimental design used was 10 x 10 alpha lattice design with three replicates. Data were collected on plant disease incidence (PDI), plant disease severity (PDS), area under disease progress curve (AUDPC), days to 50% flowering, plant height, 1000 seed weight, and grain yield. Results for analysis of variance showed highly significant differences (P < 0.001) in genotypes, location, and AUDPC, yield and yield components. Disease incidence varied significantly (P < 0.001) between locations, and Arua recorded highest disease incidence and severity of 80.6 and 2.8, respectively. Results from correlation analysis showed a highly significant (P < 0.001) positive association of downy mildew disease incidence with AUDPC (0.835) which suggests that the severity of SDM disease increased with disease incidence, whiles significant (P < 0.001) negative correlation was recorded for days to 50 % flowering (-0.302), 1000 seed weight (-0.471), and grain yield (-0.585), suggesting that grain yield and yield component decreased significantly with increase in SDM incidence and severity. Two resistant (PI 656061 and PI 533831) and four moderately resistant (E 40, MAKSO 8, PI 655990 and Epuripur) genotypes were identified from this study. These genotypes were recommended for sorghum breeding program against downy mildew disease.
•Rhus coriaria was evaluated for antifungal activity against Colletotrichum acutatum.•Sumac extract was a potential biocontrol and bioenhancer candidate.•Sumac extract significantly reduced tomato ...anthracnose disease by 82.588%.•Rhus coriaria significantly increased plant growth attributes.
The prevalence of Anthracnose disease, which is caused by a number of Colletotrichum spp., takes its toll on the tomato (Lycopersicon esculentum Mill.) and poses a significant economic constraint on its production. Successful efforts towards controlling this organism remain a deficient task. Rhus coriaria fruit extracts were subjected to screening, in vitro and in vivo, for antifungal activities. Under light and Scanning Electron Microscopy (SEM), the crude extract’s effect on the morphological structures of hyphae underwent an observation and study. Experimental results surfaced proofs that acetone, aqueous, methanol, and ethanol extracts have fungicidal properties on C. acutatum (GenBank accession No. KT215296) growth, which multiplied when extract concentrations were higher. Observations from scanning electron microscope showed that active extracts led to hyphal degradation where the hyphae were retarded. Tomato plants and fruits, which were treated with aqueous extracts, have been observed to have a significantly lower disease incidence, index, and severity. The anthracnose incidence in fruits that were coated with aqueous extract exhibited a maximum reduction with severity scores consistently at (0%). Aqueous extract in the glass house test significantly reduced the total area under the disease progress curve (AUDPC) and disease severity in the studied disease. The shoot height, root length, dry shoot height, dry root length, chlorophyll content and leaf surface area significantly improved and increased with these treatments. The results indicate that R. coriaria extract can be judged as a cost effective and eco-friendly replacement to chemical fungicides in the management of tomato anthracnose disease.
Sorghum anthracnose caused by Colletotrichum sublineolum is one of the most destructive diseases affecting sorghum production in Ethiopia. Pathogenic variability of C. sublineolum isolates on some ...sorghum differentials under greenhouse condition was evaluated in Jimma, Ethiopia. Highly significant (P < 0.001) differences among sorghum differentials, C. sublineolum isolates and their interactions on incubation period, aggressiveness, virulence index, virulence, the first and final anthracnose severity assessments, disease infection rate and AUDPC were studied. Among the interactions, the interaction between CsAs7 (isolate from Assosa zone field 7) and sorghum differentials had the shortest mean incubation period (3.5 days), highest first and final anthracnose severity, highest virulence index, fastest disease infection rate and highest AUDPC as compared to others. This isolate showed the most aggressive and virulent reaction than others followed by CsJm5. The interaction of PI570726 and SC748-5 sorghum differentials and all C. sublineolum isolates produce 100 and 80% resistant reactions, respectively and they could be used as good sources of resistance genes for breeding programs for sorghum anthracnose management.
ABSTRACT Leaf rust (Puccinia triticina) is one of the most common diseases in wheat crops. For effective control of such disease, leaf application of mixtures of triazole and strobilurin fungicides ...is recommended. The aim of this study was to evaluate the efficacy of different fungicide formulations and numbers of applications in controlling wheat leaf rust in the cultivar TBIO Pioneiro 2010. Experimental design was completely randomized, 2x2 factorial arrangement, consisting of two fungicide formulations and two numbers of applications, as well as four replicates. Treatments were: azoxystrobin + tebuconazole, three and four applications; trifloxystrobin + prothioconazole, three and four applications; and a control treatment without fungicide application. For treatments with three applications, fungicides were applied at the phenological stages of: elongation, booting and flowering. For treatments with four applications, fungicides were applied at the phenological stages of: tillering, elongation, booting and flowering. The efficiency of fungicides on leaf rust control was analyzed based on the disease severity assessment by calculating the Area Under Disease Progress Curve (AUDPC). Severity data were obtained based on percentage scores of leaf area with visible disease symptoms/signs according to Cobb’s diagrammatic scale. Fungicides with azoxystrobin + tebuconazole and trifloxystrobin + prothioconazole showed efficient control of wheat leaf rust (higher than 85%). For yield components, there was no statistical difference between numbers of applications, but there was a statistical difference between fungicide formulations, except for grain yield. Furthermore, for yield components, all fungicide treatments significantly differed from control.
RESUMO A ferrugem da folha do trigo (Puccinia triticina) é uma das doenças mais frequentes em lavouras de trigo. Para um controle efetivo dessa doença é recomendado o controle foliar através da aplicação de misturas de fungicidas triazóis e estrobilurinas. O objetivo deste estudo foi avaliar a eficácia das diferentes formulações fungicidas e do número de aplicações para o controle da ferrugem da folha do trigo na cultivar TBIO Pioneiro 2010. O delineamento experimental utilizado foi inteiramente casualizado, fatorial 2x2, consistindo em duas formulações fungicidas e dois números de aplicações, com quatro repetições. Os tratamentos foram: azoxistrobina + tebuconazol com três e quatro aplicações; trifloxistrobina + protioconazol com três e quatro aplicações; e um tratamento testemunha sem aplicação de fungicida. Nos tratamentos com três aplicações, os fungicidas foram aplicados nos estádios fenológicos de: alongamento, emborrachamento e florescimento. Os tratamentos com quatro aplicações foram realizados nos estádios fenológicos de: perfilhamento, alongamento, emborrachamento e florescimento. A eficiência dos fungicidas no controle da ferrugem foi analisada através da avaliação da severidade da doença, calculando-se a Área Abaixo da Curva de Progresso da Doença (AACPD). Os dados de severidade foram obtidos através de notas da porcentagem da área foliar com sintomas/sinais da doença segundo a escala diagramática de Cobb. Fungicidas com azoxistrobina + tebuconazol e trifloxistrobina + protioconazol apresentaram eficiência no controle de ferrugem da folha de trigo (todos acima de 85%). Em componentes de rendimento, não houve diferença estatística entre o número de aplicações, mas, houve diferença estatística entre as formulações de fungicidas, exceto para produtividade. Além disso, para os componentes do rendimento, todos os tratamentos fungicidas diferiram significativamente da testemunha.
The rice blast incited by Pyricularia oryzae caused immense losses and left rice production in a predicament situation globally. Blast can be effectively controlled with synthetic fungicides. ...However, their indiscriminate use causes resistance among the pathogens coupled with environmental pollution issues. Exploitation of microbe‐based alternatives for the management of plant diseases diminishes public concerns on the ill effects of pesticide usage in crops. Under this scenario the present investigation was designed to envisage the potential rhizosphere microflora from native rhizosphere soil samples collected from rice growing regions of three different agro‐climatic zones of (North Telangana Zone, Central Telangana Zone and Southern Telangana Zone) for the sustainable management of rice blast in Telangana state. We observed varied level of antagonism against Pyricularia oryzae under in vitro conditions. Seeds treated with native effective rhizospheric microflora exhibited significantly higher seed vigour index ranging from 1940.7 to 2183.6 compared to control. Further, these effective rhizospheric microbes were identified through cultural and morphological characteristics as well as by the sequencing internal transcribed spacer (ITS) and 16S rRNA gene sequences analysis for bacteria and fungi as Bacillus cereus, Bacillus xiamenensis, Bacillus subtilis and Trichoderma asperellum respectively. Later, bio‐efficacy tests were carried out in the field during the 2 years of Kharif 2019 and 2021 by spraying the combinations of the antagonists in association with indigenous organic sources (Panchagavya, Beejamrutham and Vermiwash) and non‐chemical sources such as Butter milk and Neem oil on healthy rice plants to assess disease inhibition under natural conditions. Results obtained from present investigation on the field bio‐efficacy studies showed significant improvement in the seedling's growth with 83.36 cm plant height, 10.40 no of panicles with an average yield of 8583.33 kg ha−1, when compared to control during 2019 and 2021 with lower AUDPC and r value. Our findings indicate that the native rhizospheric microflora in association with indigenous organic sources can be used as potential alternative strategy for the management of rice blast in Telangana region of India. The knowledge gathered from the present study can be used to develop strategies for maintaining soil quality and crop conservation to increase crop productivity with less dependency on chemical approaches.
Late blight of potato is considered to be the most devastating problem causing severe yield losses in potato worldwide. Among the different management strategies, the use of resistant cultivars is ...the most viable option, but the non‐availability of enough quantity of quality seed materials of resistant cultivars forces the farmers to grow susceptible cultivars with proper fungicide scheduling. Therefore, in the present study, chemical control using fungicide has been attempted with newer molecules in the susceptible cultivar along with a resistant cultivar as a positive control. All the tested fungicides were found safe, and no phytotoxicity was observed with any chemical at the applied rate. In resistant cultivar, no late blight was appeared in both the years, whereas maximum AUDPC was observed in the untreated control (276.3) and minimum (41.7) in mancozeb‐cymoxanil + mancozeb based scheduling which was found on par with chlorothalonil‐famoxadone + cymoxanil (51.3) and chlorothalonil‐ametoctradin + dimethomorph (53.5) based scheduling. Among the treatments, resistant cultivar, Kufri Girdhari followed by chlorothalonil‐ametoctradin + dimethomorph and mancozeb‐cymoxanil + mancozeb based fungicidal scheduling were proven as the best treatments for both the crop seasons resulting in the highest yield parameters. The disease severity showed a strong negative correlation with the tuber yield of potatoes in both the years. Based on overall observations including BC ratio, it can be concluded that, wherever seed material of resistant cultivar is available farmers should grow the same or else with susceptible cultivars the fungicidal scheduling based on mancozeb‐cymoxanil + mancozeb or chlorothalonil‐ametoctradin + dimethomorph can be followed to obtain the maximum returns with effective management of late blight at the southern hills of India.
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