scholarly journals Wheat Blast: A Disease Spreading by Intercontinental Jumps and Its Management Strategies

2021 ◽  
Vol 12 ◽  
Author(s):  
Pawan K. Singh ◽  
Navin C. Gahtyari ◽  
Chandan Roy ◽  
Krishna K. Roy ◽  
Xinyao He ◽  
...  

Wheat blast (WB) caused by Magnaporthe oryzae pathotype Triticum (MoT) is an important fungal disease in tropical and subtropical wheat production regions. The disease was initially identified in Brazil in 1985, and it subsequently spread to some major wheat-producing areas of the country as well as several South American countries such as Bolivia, Paraguay, and Argentina. In recent years, WB has been introduced to Bangladesh and Zambia via international wheat trade, threatening wheat production in South Asia and Southern Africa with the possible further spreading in these two continents. Resistance source is mostly limited to 2NS carriers, which are being eroded by newly emerged MoT isolates, demonstrating an urgent need for identification and utilization of non-2NS resistance sources. Fungicides are also being heavily relied on to manage WB that resulted in increasing fungal resistance, which should be addressed by utilization of new fungicides or rotating different fungicides. Additionally, quarantine measures, cultural practices, non-fungicidal chemical treatment, disease forecasting, biocontrol etc., are also effective components of integrated WB management, which could be used in combination with varietal resistance and fungicides to obtain reasonable management of this disease.

Author(s):  
Dung Le ◽  
Kris Audenaert ◽  
Geert Haesaert

AbstractFusarium basal rot (FBR) is a soil-borne disease that affects Allium species worldwide. Although FBR has long been recognized as a major constraint to the production of economically important Allium species, information that could support disease management remains scattered. In this review, the current knowledge on the causal agents, symptomology and epidemiology, impact, and management strategies of FBR is synthesized. We highlight that FPR is associated with different complexes of several Fusarium species, of which Fusarium oxysporum and F. proliferatum are the most prevalent. These pathogenic complexes vary in composition and virulence, depending on sites and hosts, which can be challenging for disease management. Research to improve disease management using chemical pesticides, resistance cultivars, biocontrol agents, and cultural practices has achieved both promising results and limitations. Finally, research needs and future directions are proposed for the development of effective FBR management strategies.


Pathogens ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 320
Author(s):  
Alexander Nilon ◽  
Karl Robinson ◽  
Hanu R. Pappu ◽  
Neena Mitter

Tomato spotted wilt virus (TSWV) is the type member of the genus Orthotospovirus in the family Tospoviridae and order Bunyavirales. TSWV, transmitted by several species of thrips, causes significant disease losses to agronomic and horticultural crops worldwide, impacting both the yield and quality of the produce. Management strategies include growing virus-resistant cultivars, cultural practices, and managing thrips vectors through pesticide application. However, numerous studies have reported that TSWV isolates can overcome host-plant resistance, while thrips are developing resistance to pesticides that were once effective. RNA interference (RNAi) offers a means of host defence by using double-stranded (ds) RNA to initiate gene silencing against invading viruses. However, adoption of this approach requires production and use of transgenic plants and thus limits the practical application of RNAi against TSWV and other viruses. To fully utilize the potential of RNAi for virus management at the field level, new and novel approaches are needed. In this review, we summarize RNAi and highlight the potential of topical or exogenous application of RNAi triggers for managing TSWV and thrips vectors.


2013 ◽  
Vol 64 (8) ◽  
pp. 774 ◽  
Author(s):  
K. A. Kirkby ◽  
P. A. Lonergan ◽  
S. J. Allen

Three decades of disease survey data have shown Verticillium wilt was one of the first major diseases of cotton recorded in the 1984–85 season. Survey reports the mean incidence was 4.1% in the 1984–85 season and rose to 16.6% in the 1989–90 season. Prior to 1984 all commercial varieties of cotton available in Australia were susceptible to bacterial blight and the disease was common. The adoption of the resistant varieties contributed to a dramatic decline in the incidence of bacterial blight and the removal of bacterial blight as a significant pathogen to Australian cotton crops by 1992. Survey results showed the incidence of black root rot increased on farms with a long history of growing cotton during the 1990s. Fusarium wilt of cotton was first reported in New South Wales (NSW) in 1994. The disease is now widespread, being confirmed on 86 NSW farms in six of the eight cotton production areas in NSW. These four significant plant disease ‘problems’ have challenged the cotton industry in NSW. Data provided by the surveys have indicated the relative importance of each of the diseases present and the impact of cultural practices and the adoption of new varieties on disease distribution, incidence and severity. The results have therefore been used to support and justify requests for research funding and have contributed to the development of Integrated Disease Management strategies. The NSW Department of Primary Industries continues to monitor the distribution of disease and the incidence and severity present in commercial cotton crops in all production areas of NSW. The aim of this paper is to highlight four significant cotton diseases in Australia and show relationships between cultural practices and declining and increasing incidence of disease.


1994 ◽  
Vol 34 (7) ◽  
pp. 1021 ◽  
Author(s):  
JE Hill ◽  
RJ Jr Smith ◽  
DE Bayer

Among temperate rice areas, the United States and Australia are most similar in climate and in the mechanisation of rice culture. Many weed problems, even weed species invading rice, are common to both countries; and the present technology for weed control as well as concern for the impact of these technologies to environmental quality, herbicide resistance, and other weed-related issues bear many similarities. Application of current, and any new, technologies to emerging issues in US rice weed control will therefore be directly relevant to rice production in Australia and all other temperate areas struggling with the same challenges. Weeds are a significant problem in temperate rice culture. In the United States, rice is mechanically direct-seeded, allowing weeds to germinate and establish with the crop. In the last 15 years weed growth and competition has been increased by the adoption of semi-dwarf cultivars, high N fertilisation, and, in water-seeded rice, shallow flooding. High rates, and often multiple applications, of herbicides have been necessary to maximise the yield potential of these cultural systems. Advances in cultural practices and herbicide technology have maintained, if not improved, weed control; but nearly 30 years of propanil use in the southern USA resulted in propanil-resistant barnyard grass Echinochloa crus-galli (L.) Beauv., and after 4 years of continuous use, bensulfuron resistance to 4 aquatic weed species was discovered in California. Although herbicides with different mechanisms of action are needed for alternation in resistance management strategies, fewer are likely to be available. Social and environmental concerns have slowed the development and registration of rice herbicides and increased the cost of controlling weeds. Water quality deterioration from ricefield tailwaters, drift to sensitive crops, the cost of renewing registration in aquatic systems, and weed resistance all forecast reduced herbicide use in rice. Neither cultural practices nor herbicides alone can solve weed problems in direct-seeded, mechanised rice culture. With fewer herbicides and a cultural system highly vulnerable to weed losses, integrated management strategies with better information on which to base weed control decisions will be needed to solve weed problems in temperate rice.


Plant Disease ◽  
2020 ◽  
Vol 104 (1) ◽  
pp. 60-70 ◽  
Author(s):  
Maud Thierry ◽  
Pierre Gladieux ◽  
Elisabeth Fournier ◽  
Didier Tharreau ◽  
Renaud Ioos

Rapid detection is key to managing emerging diseases because it allows their spread around the world to be monitored and limited. The first major wheat blast epidemics were reported in 1985 in the Brazilian state of Paraná. Following this outbreak, the disease quickly spread to neighboring regions and countries and, in 2016, the first report of wheat blast disease outside South America was released. This Asian outbreak was due to the trade of infected South American seed, demonstrating the importance of detection tests in order to avoid importing contaminated biological material into regions free from the pathogen. Genomic analysis has revealed that one particular lineage within the fungal species Pyricularia oryzae is associated with this disease: the Triticum lineage. A comparison of 81 Pyricularia genomes highlighted polymorphisms specific to the Triticum lineage, and this study developed a real-time PCR test targeting one of these polymorphisms. The test’s performance was then evaluated in order to measure its analytical specificity, analytical sensitivity, and robustness. The C17 quantitative PCR test detected isolates belonging to the Triticum lineage with high sensitivity, down to 13 plasmid copies or 1 pg of genomic DNA per reaction tube. The blast-based approach developed here to study P. oryzae can be transposed to other emerging diseases.


Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 847
Author(s):  
Renate Krause-Sakate ◽  
Luís Fernando Maranho Watanabe ◽  
Eduardo Silva Gorayeb ◽  
Felipe Barreto da Silva ◽  
Daniel de Lima Alvarez ◽  
...  

By having an extensive territory and suitable climate conditions, South America is one of the most important agricultural regions in the world, providing different kinds of vegetable products to different regions of the world. However, such favorable conditions for plant production also allow the development of several pests, increasing production costs. Among them, whiteflies (Hemiptera: Aleyrodidae) stand out for their potential for infesting several crops and for being resistant to insecticides, having high rates of reproduction and dispersal, besides their efficient activity as virus vectors. Currently, the most important species occurring in South America are Bemisia afer, Trialeurodes vaporariorum, and the cryptic species Middle East-Asia Minor 1, Mediterranean, and New World, from Bemisia tabaci complex. In this review, a series of studies performed in South America were compiled in an attempt to unify the advances that have been developed in whitefly management in this continent. At first, a background of the current whitefly distribution in South American countries as well as factors affecting them are shown, followed by a background of the whitefly transmitted viruses in South America, addressing their location and association with whiteflies in each country. Afterwards, a series of management strategies are proposed to be implemented in South American fields, including cultural practices and biological and chemical control, finalizing with a section containing future perspectives and directions for further research.


Author(s):  
Apurba Kumar Chowdhury ◽  
Mahender Singh Saharan ◽  
Rashmi Aggrawal ◽  
Paritosh Kumar Malaker ◽  
N. C. D. Barma ◽  
...  

2021 ◽  
Vol 1 (2) ◽  
pp. 93-100
Author(s):  
Prakriti Ghimire ◽  
Nikku Bhetwal

The fall armyworm (FAW) (Spodoptera frugiperda) is a polyphagous crop pest which has a higher possibility of spreading all over the world, risking the agricultural potential yield by reducing the productivity and production. The rapid breeding ability with a speed migrating tendency along with the voracious feeding nature, has made the monitoring and control of this pest more difficult. With more than 80 host species, the agricultural devastation caused by FAW has been a threat to the agricultural sector. So, an integrated approach of pest management should be in our top priority while dealing with controlling of the pest. Various cultural practices like deep ploughing before the rain onset and intercropping with different leguminous crops has helped to decrease the faw population along with other physical, biological, mechanical and chemical methods. However, chemical methods should be applied below the economic threshold level and only when the pest population is growing in such a rapid form that the other methods has failed to affect the pest population. This review mainly focuses on the Insect distribution, its biology, host preference, field damage along with its management strategies that has been researched by various researchers from different corners of the world.


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