scholarly journals Resistance to the SDHI Fungicides Boscalid and Fluopyram in Podosphaera xanthii Populations from Commercial Cucurbit Fields in Spain

2021 ◽  
Vol 7 (9) ◽  
pp. 733
Author(s):  
Alejandra Vielba-Fernández ◽  
Álvaro Polonio ◽  
Laura Ruiz-Jiménez ◽  
Antonio de Vicente ◽  
Alejandro Pérez-García ◽  
...  
Keyword(s):  
Management Practices ◽  
Rapid Development ◽  
Resistance Management ◽  
Leaf Disc ◽  
Lamp Assay ◽  
Primary Control ◽  
Podosphaera Xanthii ◽  
Growing Seasons ◽  
Development Of Resistance ◽  
Plant Assays

Powdery mildew is caused by Podosphaera xanthii, and is one of the most important diseases that attacks Spanish cucurbit crops. Fungicide application is the primary control tool; however, its effectiveness is hampered by the rapid development of resistance to these compounds. In this study, the EC50 values of 26 isolates were determined in response to the succinate dehydrogenase inhibitor (SDHI) fungicides boscalid and fluopyram. From these data, the discriminatory doses were deduced and used for SDHI resistance monitoring during the 2018 and 2019 growing seasons. Of the 298 isolates analysed, 37.9% showed resistance to boscalid and 44% to fluopyram. Although different phenotypes were observed in leaf disc assays, the resistant isolates showed the same phenotype in plant assays. Compared to sensitive isolates, two amino acid changes were found in the SdhC subunit, A86V and G151R, which are associated mostly with resistance patterns to fluopyram and boscalid, respectively. Furthermore, no significant differences were observed in terms of fitness cost between the selected sensitive and resistant isolates analysed here. Lastly, a loop-mediated isothermal amplification (LAMP) assay was developed to detect A86V and G151R mutations using conidia obtained directly from infected material. Our results show that growers could continue to use boscalid and fluopyram, but resistance management practices must be implemented.

scholarly journals First Report of Resistance to Cyflufenamid in Podosphaera xanthii, Causal Agent of Powdery Mildew, from Melon and Zucchini Fields in Italy

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1581-1581 ◽  
Author(s):  
A. Pirondi ◽  
I. M. Nanni ◽  
A. Brunelli ◽  
M. Collina
Keyword(s):  
Powdery Mildew ◽  
Fungicide Resistance ◽  
Management Strategies ◽  
Resistance Management ◽  
Personal Communication ◽  
Causal Agent ◽  
Infected Leaf ◽  
Podosphaera Xanthii ◽  
Growing Seasons ◽  
Action Committee

The fungicide cyflufenamid (phenyl-acetamide, Fungicide Resistance Action Committee [FRAC] code U6) was approved for use in Italy in 2011 as Takumi (Certis Europe, Utrecht, The Netherlands) to control Podosphaera xanthii (Castagne) U. Braun. & N. Shishkoff, the main causal agent of cucurbit powdery mildew. Considering that strains of this pathogen have developed resistance to strobilurin (5) and demethylation inhibitor (DMI) (4) fungicides, cyflufenamid represented a viable alternative to control this disease. However, this fungicide is also prone to resistance development as illustrated by resistance of P. xanthii in Japan (3). In the 2012 and 2013 growing seasons, significant declines in cyflufenamid efficacy were observed in two experimental fields in the Apulia (AP) and Emilia-Romagna (ER) regions of Italy on Cucumis melo and Cucurbita pepo, respectively. Takumi had been applied four times at the recommended field rate of 0.15 liter/ha (15 μg/ml of active ingredient [a.i.]) each growing season since 2010 in each field. Powdery mildew-infected leaf samples were collected in 2012 from both fields (25 isolates from AP and 19 from ER), and from five gardens (one isolate per garden); while in 2013, samples were collected only from the ER field (two polyconidial isolates). Isolates were maintained on detached zucchini cotyledons (1). Sensitivity of the isolates to cyflufenamid was determined by leaf disk bioassays (4) using Takumi at 0.01, 0.1, 1, 10, 20, and 50 μg a.i./ml. The 50% effective concentration (EC50) and the minimum inhibitory concentration (MIC) values were calculated (2). Isolates collected in ER and the gardens in 2012 all had an EC50< 0.01 μg/ml, and the MIC ranged from <0.01 to <1 μg/ml. Isolates from AP in 2012 had elevated EC50 values, from 0.230 to >50 μg/ml, and MIC values from <10 to >50 μg/ml; by 2013, the EC50 values of ER isolates ranged from 3.35 to >50 μg/ml. Based on the mean EC50 value of 0.0019 μg/ml for sensitive isolates of P. xanthii in Japan (2), isolates from both the ER field and gardens in 2012 were considered sensitive to cyflufenamid. Additionally, EC50 values of AP isolates from 2012 and ER isolates from 2013 were greater than those of sensitive isolates, indicating a shift in sensitivity toward resistance to cyflufenamid (resistance factor >100 [2]). Consequently, poor control of powdery mildew with cyflufenamid applications in the AP and ER trials was most likely a result of fungicide resistance. Isolates from these fields were exposed to selection pressure for fungicide resistance because cyflufenamid was applied more times than permitted in the label instructions. However, control of powdery mildew in 2013 was not as effective as in previous years in commercial fields in AP (C. Dongiovanni, personal communication). This observation, combined with proof of reduced sensitivity of some P. xanthii strains in Italy to cyflufenamid, highlights the need for implementing resistance management strategies to minimize the risk of fungicide resistant strains developing in cucurbit fields. References: (1) B. Álvarez and J. A. Torés. Bol. San. Veg. Plagas 23:283, 1997. (2) M. Haramoto et al. J. Pest. Sci. 31:397, 2006. (3) H. Hosokawa et al. Jpn. J. Phytopathol. 72:260, 2006. (4) M. T. McGrath et al. Plant Dis. 80:697, 1996. (5) M. T. McGrath and N. Shishkoff. Plant. Dis. 87:1007, 2003.

Acaricide resistance in Panonychus citri and P. ulmi (Acari: Tetranychidae): Molecular mechanisms and management implications

2021 ◽  
Author(s):  
Jahangir Khajehali ◽  
Elaheh Shafiei Alavijeh ◽  
Mohammad Ghadamyari ◽  
Dejan Marčić
Keyword(s):  
Molecular Mechanisms ◽  
Rapid Development ◽  
Resistance Management ◽  
Panonychus Ulmi ◽  
Acaricide Resistance ◽  
Panonychus Citri ◽  
Citrus Red Mite ◽  
Development Of Resistance ◽  
Citrus Groves ◽  
Fruit Orchards

The European red mite, Panonychus ulmi (Koch), and the citrus red mite, P. citri (McGregor) (Acari: Tetranychidae), are destructive mite pests in pome/stone fruit orchards and citrus groves, respectively, the management of these two spider mites species has relied largely on the use of synthetic acaricides. However, frequent, long-term use of acaricides has caused rapid development of resistance in P. ulmi and P. citri populations worldwide. Levels of resistance in P. ulmi and P. citri are exceeded only by that in the two-spotted spider mite, Tetranychus urticae Koch. Recent research on T. urticae has provided new insights into the molecular mechanisms of acaricide resistance. The molecular basis of resistance in P. ulmi and P. citri populations has been less thoroughly studied. In this brief review, the current understanding of the molecular mechanisms of toxicokinetic and toxicodynamic resistance of P. ulmi and P. citri to acaricides, as well as implications of the findings for the resistance management, are discussed.  

Herbicide Resistance: Where are we? How did we Get here? Where are we Going?

1995 ◽  
Vol 9 (4) ◽  
pp. 850-856 ◽  
Author(s):  
Dale L. Shaner
Keyword(s):  
Weed Management ◽  
Management Practices ◽  
Resistance Management ◽  
Cost Effective ◽  
Integrated Weed Management ◽  
Weed Species ◽  
Environmentally Sustainable ◽  
Development Of Resistance ◽  
Working Groups ◽  
Rigid Ryegrass

The first significant cases of herbicide-resistant weed populations were to the triazines in the 1970s. In the last 10 years there has been an increase in the number of weed populations that have become resistant to an array of herbicides. In some of these cases, like rigid ryegrass in Australia, a multitude of resistant biotypes has evolved with different mechanisms of resistance. If the present trend continues, the number of herbicides effective on certain weed species may diminish rapidly. To counteract this trend, industry has organized a number of intercompany working groups to specifically address the development of resistance and to implement plans to manage resistance. University and extension along with industry personnel across the world have begun educating growers on resistance management. However, this effort needs to be intensified to find new solutions for controlling weeds through the use of integrated weed management practices that incorporate new and established herbicides with cultural, mechanical, and biological control methods. The challenge is to develop cost effective, environmentally sustainable programs for weed control while maintaining the present efficiency in food and fiber production so that needs of an ever expanding human population can be met.

Fungicide Resistance—Lessons for Herbicide Resistance Management?

1995 ◽  
Vol 9 (4) ◽  
pp. 840-849 ◽  
Author(s):  
Tobin L. Peever ◽  
Michael G. Milgroom
Keyword(s):  
Disease Control ◽  
Fungicide Resistance ◽  
Rapid Development ◽  
Management Strategies ◽  
Experimental Studies ◽  
Resistance Management ◽  
Pathogenic Fungi ◽  
Systemic Fungicides ◽  
Development Of Resistance ◽  
Pathogen Populations

Resistance to agricultural fungicides has increaséd dramatically in the past twenty years, following the introduction of systemic fungicides. Disease control failures associated with fungicide resistance have occurred with many classes of fungicides and in many genera of plant-pathogenic fungi. In some cases, resistance evolved extremely rapidly making the chemicals ineffective for disease control only a few years after they were introduced.The rapid development of resistance to systemic fungicides has led to efforts to develop strategies to avoid or delay the evolution of fungicide resistance in plant pathogen populations. Despite a widespread interest in managing fungicide resistance, very few experimental studies have been performed to elucidate the important factors controlling resistance development. Most fungicide resistance studies have consisted of anecdotal field observations which have rarely been followed up with experimentation. In order to understand what factors affect the evolution of resistance, and to use this information to design effective resistance management strategies, more experimental studies are required.

scholarly journals Identification and documentation of herbicide resistance

2005 ◽  
Vol 75 (4) ◽  
pp. 85-90 ◽  
Author(s):  
I.M. Heap
Keyword(s):  
Herbicide Resistance ◽  
Rapid Development ◽  
Resistance Management ◽  
Petri Dish ◽  
Response Curves ◽  
Susceptible Population ◽  
Development Of Resistance ◽  
Whole Plant ◽  
Biochemical Detection ◽  
Annual Weeds

Proactive herbicide resistance management programs rely upon early detection of resistant populations and knowledge of which combinations of weed and herbicide are prone to the development of resistance. Annual weeds that are prolific seed producers, genetically diverse, and repeatedly exposed to a single herbicide mode of action, are prone to rapid development of resistance. When resistance is suspected, seed samples are collected and evaluated using a whole plant bioassay. Whole plant bioassays are conducted underfield, growth room, or Petri dish conditions. Complete dose response curves for the suspected resistant and a reference susceptible population are used to verify resistance. Bioassay, conducted in growth rooms, is the most reliable method for identification of new cases of herbicide resistance. Bioassays, based on the biochemical detection of a single mechanism of resistance, are not reliable for screening for new occurrences of resistance.

Solid Waste Management on Romanian Households

2018 ◽  
Vol 68 (12) ◽  
pp. 2941-2947
Author(s):  
George Ungureanu ◽  
Gabriela Ignat ◽  
elena Leonte ◽  
Carmen Luiza Costuleanu ◽  
Nicoleta Stanciu ◽  
...  
Keyword(s):  
Waste Management ◽  
Solid Waste ◽  
Agricultural Development ◽  
Management Practices ◽  
Solid Waste Management ◽  
Raw Materials ◽  
Rapid Development ◽  
Disposal Site ◽  
Solid Waste Disposal ◽  
Factors Affecting

The problem associated with the household behavior on solid waste disposal site in today�s society is complex because of the large quantity and diverse nature of the wastes. Due increase the population, rapid development, global agricultural development has moved rapidly, limitations of financing, emerging limitations of both energy and raw materials and also add to the complexity of any waste management system, large quantities of wastes are being generated in different forms such as solid, liquid and gases. This research explored factors affecting the level of participation in solid waste segregation and recycling of households in Romania, as well as examining current Romania households waste management practices and their knowledge of waste management. This study investigated the solid waste situation and the organization of solid waste management in both urban and rural settings from the perspective of households. Solid waste management is a key component of public services which needs to serve the urban and rural municipalities in an efficient way in order to maintain a decent standard of public health.

scholarly journals Fitness of Herbicide-Resistant Weeds: Current Knowledge and Implications for Management

Plants ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 469 ◽  
Author(s):  
Vila-Aiub
Keyword(s):  
Life History ◽  
Herbicide Resistance ◽  
Management Practices ◽  
Current Knowledge ◽  
Resistance Management ◽  
Fitness Cost ◽  
Plant Fitness ◽  
Resistance Mutations ◽  
Fitness Costs ◽  
Wide Range

Herbicide resistance is the ultimate evidence of the extraordinary capacity of weeds to evolve under stressful conditions. Despite the extraordinary plant fitness advantage endowed by herbicide resistance mutations in agroecosystems under herbicide selection, resistance mutations are predicted to exhibit an adaptation cost (i.e., fitness cost), relative to the susceptible wild-type, in herbicide untreated conditions. Fitness costs associated with herbicide resistance mutations are not universal and their expression depends on the particular mutation, genetic background, dominance of the fitness cost, and environmental conditions. The detrimental effects of herbicide resistance mutations on plant fitness may arise as a direct impact on fitness-related traits and/or coevolution with changes in other life history traits that ultimately may lead to fitness costs under particular ecological conditions. This brings the idea that a “lower adaptive value” of herbicide resistance mutations represents an opportunity for the design of resistance management practices that could minimize the evolution of herbicide resistance. It is evident that the challenge for weed management practices aiming to control, minimize, or even reverse the frequency of resistance mutations in the agricultural landscape is to “create” those agroecological conditions that could expose, exploit, and exacerbate those life history and/or fitness traits affecting the evolution of herbicide resistance mutations. Ideally, resistance management should implement a wide range of cultural practices leading to environmentally mediated fitness costs associated with herbicide resistance mutations.

scholarly journals Estimating Soil Water Susceptibility to Salinization in the Mekong River Delta Using a Modified DRASTIC Model

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1636
Author(s):  
Thanh N. Le ◽  
Duy X. Tran ◽  
Thuong V. Tran ◽  
Sangay Gyeltshen ◽  
Tan V. Lam ◽  
...  
Keyword(s):  
Land Use ◽  
Soil Water ◽  
Management Practices ◽  
Global Climate ◽  
Anthropogenic Activities ◽  
Rapid Development ◽  
Anthropogenic Factors ◽  
Drastic Model ◽  
River Catchment ◽  
Modified Drastic

Saltwater intrusion risk assessment is a foundational step for preventing and controlling salinization in coastal regions. The Vietnamese Mekong Delta (VMD) is highly affected by drought and salinization threats, especially severe under the impacts of global climate change and the rapid development of an upstream hydropower dam system. This study aimed to apply a modified DRASTIC model, which combines the generic DRASTIC model with hydrological and anthropogenic factors (i.e., river catchment and land use), to examine seawater intrusion vulnerability in the soil-water-bearing layer in the Ben Tre province, located in the VMD. One hundred and fifty hand-auger samples for total dissolved solids (TDS) measurements, one of the reflected salinity parameters, were used to validate the results obtained with both the DRASTIC and modified DRASTIC models. The spatial analysis tools in the ArcGIS software (i.e., Kriging and data classification tools) were used to interpolate, classify, and map the input factors and salinization susceptibility in the study area. The results show that the vulnerability index values obtained from the DRASTIC and modified DRASTIC models were 36–128 and 55–163, respectively. The vulnerable indices increased from inland districts to coastal areas. The Ba Tri and Binh Dai districts were recorded as having very high vulnerability to salinization, while the Chau Thanh and Cho Lach districts were at a low vulnerability level. From the comparative analysis of the two models, it is obvious that the modified DRASTIC model with the inclusion of a river or canal network and agricultural practices factors enables better performance than the generic DRASTIC model. This enhancement is explained by the significant impact of anthropogenic activities on the salinization of soil water content. This study’s results can be used as scientific implications for planners and decision-makers in river catchment and land-use management practices.

scholarly journals Effect of Weed Management on the Parasitoid Community in Mediterranean Vineyards

Biology ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Gabriella Möller ◽  
Tamar Keasar ◽  
Idan Shapira ◽  
Daniella Möller ◽  
Marco Ferrante ◽  
...  
Keyword(s):  
Cover Crops ◽  
Weed Management ◽  
Soil Conservation ◽  
Management Practices ◽  
Ground Cover ◽  
Parasitoid Species ◽  
Parasitoid Community ◽  
Growing Seasons ◽  
Conservation Biocontrol ◽  
Suction Sampling

Enriching agroecosystems with non-crop vegetation is a popular strategy for conservation biocontrol. In vineyards, the effects of specific seeded or planted cover crops on natural enemies are well-studied, whereas conserving spontaneously developing weeds received less attention. We compared parasitoid communities between matched pairs of vineyard plots in northern Israel, differing in weed management practices: “herbicide”, repeated herbicide applications vs. “ground cover”, maintaining resident weeds and trimming them when needed. Using suction sampling, we assessed the parasitoids’ abundance, richness, and composition during three grape-growing seasons. Ground cover plots had greater parasitoid abundances and cumulative species richness than herbicide-treated plots, possibly because of their higher vegetation cover and richness. Dominant parasitoid species varied in their magnitude and direction of response to weed management. Their responses seem to combine tracking of host distributions with attraction to additional vegetation-provided resources. Parasitoid community composition was mildly yet significantly influenced by weed management, while season, year, and habitat (weeds vs. vine) had stronger effects. Vineyard weeds thus support local biocontrol agents and provide additional previously demonstrated benefits (e.g., soil conservation, lower agrochemical exposure) but might also attract some crop pests. When the benefits outweigh this risk, weed conservation seems a promising step towards more sustainable agricultural management.

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