scholarly journals Native perennial and non-native annual grasses shape pathogen community composition and disease severity in a California grassland

2020 ◽  
Author(s):  
Amy E. Kendig ◽  
Erin R. Spear ◽  
S. Caroline Daws ◽  
S. Luke Flory ◽  
Erin A. Mordecai
Keyword(s):  
Disease Severity ◽  
Community Composition ◽  
Fungal Pathogens ◽  
Disease Risk ◽  
Host Density ◽  
Perennial Grasses ◽  
List Type ◽  
Host Group ◽  
Annual Grasses ◽  
California Grassland

AbstractThe densities of highly competent plant hosts may shape pathogen community composition and disease severity, altering disease risk and impacts. Life history and evolutionary history influence host competence: longer-lived species tend to be better defended than shorter-lived species and pathogens adapt to infect species with which they have longer evolutionary histories. It is unclear, however, how the densities of species that differ in competence due to life and evolutionary histories affect plant pathogen community composition and disease severity.We examined foliar fungal pathogens on two host groups in a California grassland: native perennial and non-native annual grasses. We first characterized pathogen community composition and disease severity on the two host groups to approximate differences in competence. We then used observational and manipulated gradients of native perennial and non-native annual grass densities to assess the effects of each host group on pathogen community composition and disease severity in 1-m2 plots.Native perennial and non-native annual grasses hosted distinct pathogen communities but shared generalist pathogens. Native perennial grasses hosted pathogens with larger host ranges and experienced greater disease severity (75% higher proportions of leaves with lesions) than non-native annuals. While the relative abundances of three common pathogens tended to shift, and disease severity of native perennial grasses tended to increase with increasing densities of both host groups, these changes were not statistically significant.Synthesis. The life and evolutionary histories of grasses likely influence their competence for different pathogen species, leading to distinct pathogen communities and differences in disease severity. However, there was no evidence that the density of either host group significantly affected pathogen community composition or disease severity. Therefore, variation in competence for different pathogens likely shapes pathogen community composition and disease severity but may not interact with host density to alter disease risk and impacts at small scales.

Effect of Artificial Grassland Establishing on the Vegetation Restoration in the Degraded Ecosystem

2014 ◽  
Vol 955-959 ◽  
pp. 3474-3478
Author(s):  
Tie Jun Sun
Keyword(s):  
Species Diversity ◽  
Community Composition ◽  
Early Period ◽  
Vegetation Restoration ◽  
Bromus Inermis ◽  
Perennial Grasses ◽  
Species Number ◽  
Composition And Structure ◽  
Degraded Ecosystem ◽  
Annual Grasses

Experiment was executed to plant Bromus inermis artificially in the degraded ecosystem, and study effect of grass planting on vegetation restoration. The results indicated that natural vegetation restored rapidly in the degraded ecosystem in two years after grass planted. But species diversity changed little in the early period of vegetation restoration, while vegetation biomass, coverage and anti-interference improved quickly. In addition, species number and important value of perennial grasses increased while those of annual grasses decreased. Then community composition with annual plants mainly changed gradually into that with perennial plants mainly after Bromus inermis planted. However, overground biomass and coverage of restored vegetation and dominance of Bromus inermis planted decreased after vegetation cut once a year. And species diversity and important value of annual grasses increased. Thus it could be good for uniformity of species distribution and stability of community composition and structure to develop.

Efficacy of Different Level of Systemic Fungicides on Management of Rice Blast at Baitadi, Nepal

2020 ◽  
Vol 7 ◽  
pp. 33-42
Author(s):  
Ashok Acharya ◽  
Prabin Ghimire ◽  
Dhurba Raj Joshi ◽  
Kishor Shrestha ◽  
Govinda Sijapati ◽  
...  
Keyword(s):  
Disease Severity ◽  
Rice Blast ◽  
Fungal Pathogens ◽  
Block Design ◽  
Rice Variety ◽  
Disease Suppression ◽  
Systemic Fungicide ◽  
Disease Development ◽  
Systemic Fungicides ◽  
Different Levels

Rice blast (Pyriculariaoryzae Cavara) is one of the most devastating diseases affecting the rice crop in across the world. Systemic fungicides are used for the suppression of blast diseases caused by fungal pathogens. Propiconazole and Carbendazim are commercial chemical control products available in markets for the control of the fungal pathogen. An experiment was conducted to examine the effectiveness of systemic fungicide on suppression of rice blast incidence in farmers' field during wet seasons in 2016. The treatments consisted of the use of different levels of propiconazole and Carbendazim on ‘Rato Basmati’ a landrace rice variety. The experiments were arranged in a randomized complete block design with three replications. The disease was scored according to the standard scale developed by the International Rice Research Institute (IRRI). Disease severity and Area under Disease Progressive curve (AUDPC) was computed based on that scale score. Propiconazole and Carbendazim at different levels reduce disease development than no treatment (control). But its efficacy was not consistent. The magnitude of disease suppression by Propiconazole was high as compared to Carbendazim. The application of propiconazole at the rate of 1.5 ml effectively reduced disease severity and AUDPC at different dates. So propiconazole at the rate of 1.5 ml thrice at weekly intervals is effective to reduce the disease development

scholarly journals Performance and profitability of rain-based thresholds for timing fungicide applications in soybean rust control

2020 ◽  
Author(s):  
Gustavo C. Beruski ◽  
Emerson Medeiros Del Ponte ◽  
André B. Pereira ◽  
Mark L. Gleason ◽  
Gil M. S. Câmara ◽  
...  
Keyword(s):  
Disease Severity ◽  
Disease Risk ◽  
Climatic Conditions ◽  
Soybean Rust ◽  
Yield Data ◽  
Growing Seasons ◽  
Action Threshold ◽  
Temperature Thresholds ◽  
Fungicide Mixtures ◽  
Control Disease

AbstractSoybean rust (SBR), caused by the fungus Phakopsora pachyrhizi, is the most damaging disease of soybean in Brazil. Effective management is achieved by means of calendar-timed sprays of fungicide mixtures, which do not explicitly consider weather-associated disease risk. Two rainfall-based action thresholds of Disease Severity Values (DSV50 and DSV80) were proposed and compared with two leaf wetness duration-temperature thresholds of Daily Values of Infection Probability (DVIP6 and DVIP9) and with a calendar (CAL) program, with regards to performance and profitability. An unsprayed check treatment plot was included for calculating relative control. Disease severity and yield data were obtained from 29 experiments conducted at six sites across four states in Brazil during 2012-13, 2014-15 and 2015-16 growing seasons, which represented different growing regions and climatic conditions. The less conservative rainfall action threshold (DSV80) resulted in fewer fungicide sprays compared with the other treatments and the more conservative one (DSV50) resulted in fewer sprays than the DVIP thresholds. Yield was generally higher with the increase of spray number, but the economic analysis showed no significant differences on the risk of not offsetting the costs of fungicide sprays regardless of the system. Therefore, based on the simplicity and the profitability of the rain-based model, the system is a good candidate for incorporating into management of SBR in soybean production fields in Brazil.

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