scholarly journals Incidence of Phytophthora and Pythium Infection and the Relation to Cultural Conditions in Commercial Blueberry Fields

HortScience ◽  
2008 ◽  
Vol 43 (1) ◽  
pp. 260-263 ◽  
Author(s):  
David R. Bryla ◽  
Robert G. Linderman ◽  
Wei Q. Yang

Fifty-five commercial blueberry (Vaccinium spp.) fields were sampled in northwest Oregon in 2001 to determine the incidence of Phytophthora and Pythium root rot pathogens and identify cultural factors that increase the probability of developing infection. Phytophthora was detected in 24% and Pythium was detected in 85% of the fields sampled. The only species of Phytophthora identified in the study was P. cinnamomi. Root infection by P. cinnamomi was significantly related to cultivar with incidence observed more frequently than expected in ‘Duke’ and ‘Bluecrop’. Both blueberry cultivars are two of the most popular grown in the region, representing 42% of the fields in this survey and ≈46% of the total area planted in Oregon. Two other cultivars found infected by P. cinnamomi were ‘Rubel’ and ‘Briggitta Blue’, together accounting for an additional 24% of the fields surveyed. Phytophthora was not detected in fields planted with ‘Berkeley’, ‘Bluejay’, ‘Bluetta’, ‘Darrow’, ‘Earliblue’, ‘Elliott’, and ‘Powderblue’, each of which represented only 2% to 7% of the fields surveyed. Pythium spp. were identified to genus only, but one or more species of Pythium was found in all 11 cultivars included in the survey. Occurrence of either Phytophthora or Pythium was unrelated to soil type, planting age, or cultural practices such as bed type, cover crop, mulch, irrigation system, fertilizer application, fungicide use, or the source of plant material used in the fields. Overall, most fields with Phytophthora or Pythium remained largely symptomless under good soil drainage conditions and had similar levels of vigor as those without the pathogens.

1997 ◽  
Vol 87 (3) ◽  
pp. 242-249 ◽  
Author(s):  
Jean B. Ristaino ◽  
Gregory Parra ◽  
C. Lee Campbell

Four mechanisms of dispersal of propagules of Phytophthora capsici were investigated through modifications in cultural practices and fungicide applications in field plots of bell pepper (Capsicum annuum). Dispersal of soil inoculum was suppressed, and final incidence of disease was 2.5 to 43% when stubble from a fall-sown, no-till, wheat cover crop was present. Final disease incidence was 71 to 72% and pathogen spread occurred within and across rows when all dispersal mechanisms were operative in plots of pepper planted into bare soil. Final disease incidence was 42 to 78% with black plastic mulch when a sporulating pepper fruit placed on the surface served as the source of initial inoculum. The fungicide metalaxyl applied in the irrigation system did not suppress within-row spread of surface inoculum from a sporulating fruit on plastic, but did limit across-row spread; final disease incidence in metalaxyl-treated plots was 11.5 to 14%. Pathogen dispersal mechanisms were modified most dramatically by the no-till cropping system. Thus, simple changes in cultural practices can have dramatic effects on the development of Phytophthora epidemics. Ecologically based disease management strategies have the potential to reduce our reliance on agrichemicals in this and similar pathosystems.


HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 671f-671
Author(s):  
M. Marutani ◽  
R. Quitugua ◽  
C. Simpson ◽  
R. Crisostomo

A demonstration vegetable garden was constructed for students in elementary, middle and high schools to expose them to agricultural science. On Charter Day, a University-wide celebration, students were invited to the garden on the University campus. The purpose of this project was twofold: (1) for participants to learn how to make a garden and (2) for visitors to see a variety of available crops and cultural techniques. Approximately 30 vegetable crops were grown. The garden also presented some cultural practices to improve plant development, which included weed control by solarization, mulching, a drip irrigation system, staking, shading and crop cover. Different types of compost bins were shown and various nitrogen-fixing legumes were displayed as useful hedge plants for the garden.


2021 ◽  
Vol 2 (44) ◽  
pp. 22-22
Author(s):  
Alexander Saakian ◽  
◽  

The taxonomic composition and incidence of phytopathogenic fungi on the roots of soft spring wheat Triticum aestivum L. of nine varieties of Siberian origin (Altayskaya 70, Altayskaya 75, Krasnoyarskaya 12, Novosibirskaya 15, Novosibirskaya 16, Novosibirskaya 29, Novosibirskaya 31, Novosibirskaya 41 and Svirel) cultivated using wheat and fallow as a predecessor, was studied in the area of Kansk-Krasnoyarsk forest-steppe. Average incidence of fungal root infection was 24%. In plants grown using wheat as a predecessor, the incidence was statistically significantly (p <0.05) higher than in plants grown using fallow as a predecessor (27.3 versus 20.6%). Statistically significant (p <0.05) differences in the prevalence of root infection were revealed between cultivars. The maximal prevalence (33.3 and 32.3%, respectively) on average for the wheat predecessor and fallow was found for the varieties Svirel and Altayskaya 75, the minimal (16.7%) for the varieties Novosibirskaya 16 and Altayskaya 70. The complex of phytopathogenic fungi on the roots is represented by Fusarium spp., Bipolaris sorokiniana and Alternaria spp. (31.4, 44.9 and 23.7% of the pathogenic complex on average for varieties and variants, respectively). The composition of pathogens statistically significantly (p <0.01) depends on the predecessor. In the plants cultivated using wheat as a predecessor, the proportion of Alternaria spp. was higher whereas proportions of Fusarium spp. and Bipolaris sorokiniana were lower. No differences in prevalence and taxonomic composition of root infection between varieties originated from Novosibirsk territory, Krasnoyarsk territory and Altay territory were found. Keywords: SPRING WHEAT, ROOT ROT, KRASNOYARSK TERRITORY, FUSARIUM SPP., BIPOLARIS SOROKINIANA, ALTERNARIA SPP


2021 ◽  
Author(s):  
Alemante A Ayalew ◽  
Zeytu G Asfaw ◽  
Solomon A Lemma

Abstract Background: HIV/AIDS pandemic seriously ravaged the world for the past three decades. It left the world with full of complicated social, economic and political problems. The problem has continued as major health problems for most developing countries, including Ethiopia. Socio-cultural practices which are predominantly determining the life of most of these peoples have structured the spread of HIV/AIDS. The aim of this study was to investigate how socio-cultural factors are affecting patients' adherence at ART clinics in Hawassa and Yirgalem Referral Hospitals. Methods: Qualitative and quantitative designs were used to collect the data. Results: The findings have shown that for fear of stigma and discrimination at family and community levels forced patients' affected adherence at ART clinics. People living with HIV were forced to travel long distance to get rid of social exclusion and isolation that resulting in drug interruptions and drop outs. The findings have also shown that most of the followers of protestant religion make believe that HIV could be cured and boycotted them from taking ART drugs. Moreover, confidentiality of information about HIV positive children living with care givers and newly tested patients found to be resistant to start or continue their drugs. Sense of wellbeing elicited form long term ART drugs effects made patients to imagine complete healing thereby dropping their treatment. Conclusions: The findings made clear that multidimensional socio-cultural factors structure and restructure adherence problems at the ART clinics in the study hospitals. Interventions targeting to change socio-cultural factors play crucial roles to prevent and control new infections, occurrence of drug resistant strains, and social and economic repercussions in the society.


1962 ◽  
Vol 42 (2) ◽  
pp. 286-293 ◽  
Author(s):  
A. D. Smith ◽  
J. S. Horricks ◽  
J. E. Andrews

When four varieties of winter wheat (Yogo, Kharkov 22 M.C., Jones Fife, and Elgin) were sown into wheat, oat, or barley cover crops, the yields were lower than when they were sown on fallow. The yield of winter wheat sown into the different cover crops was highest in barley and lowest in wheat cover crop. When the growth of cover crops was abundant, the yield of winter wheat was reduced. Application of ammonium-phosphate-sulphate fertilizer (16-20-0) increased the yield of winter wheat and generally decreased the severity of common root rot. Winter survival was generally greater when winter wheat was sown into cover crops than when it was sown on fallow. Root rot was most severe in winter wheat sown into wheat cover and was progressively less severe when sown into fallow, barley, or oat cover. Neither blade-cultivating nor mowing the cover crop prior to seeding the winter wheat appreciably affected the yield.


Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 843
Author(s):  
Hannah R. Talton ◽  
Elena M. Rhodes ◽  
Carlene A. Chase ◽  
Marilyn E. Swisher ◽  
Justin M. Renkema ◽  
...  

The strawberry seed bug, Neopamera bilobata (Say), is an emerging pest of organic and conventional strawberries in Florida. There is limited information on this Rhyparochromidae species. Thus, the type of injury caused is not clearly documented and management recommendations are lacking. In this study, we evaluated the effect of strawberry cultivars, cover crops, and the presence of runners on N. bilobata populations and yield. We also investigated the effect of select cultivars and the presence of runners on N. bilobata injury levels. In addition, we used fruit bagging experiments to investigate the effects of N. bilobata population and life stage (nymph vs. adult) on strawberry fruits. There was no effect of cover crop or cultivar on N. bilobata populations. In the 2017–2018 season, strawberry plots with runners contained higher N. bilobata populations compared with plots without runners, and adult infestation was significantly higher than nymphal infestation. In the 2018–2019 season, the trend was reversed with higher numbers of N. bilobata collected in plots with runners removed. In the 2019–2020 season, there was no significant difference in N. bilobata populations in plots with and without runners. In both 2018–2019 and 2019–2020, nymphal infestation was higher than adult infestation. Less injury was recorded in “Florida Brilliance” compared with the other cultivars tested. In the 2019–2020 season, less injury was recorded from plots without runners while the difference was not significant in 2017–2018 or 2018–2019. Releasing five and ten adult N. bilobata on ripe (red) fruit produced a similar level of injury while no injury to unripe (green) fruit was observed. Both adults and nymphs cause injury to ripe fruit. These findings can help contribute to the development of an integrated pest management program for strawberry N. bilobata.


1934 ◽  
Vol 10 (1) ◽  
pp. 115-124 ◽  
Author(s):  
W. C. Broadfoot

The crown and root tissue from 43,305 of 47,360 plants examined in this investigation yielded Helminthosporium sativum, Fusarium culmorum and other Fusarium spp., either alone or in combination with these or other fungi and bacteria. It was the exception for any mature plant, the surface tissue of which was disinfected, to be free from fungi or bacteria. None of the various crop sequences or cultural practices used in this study appeared to significantly affect more than another the relative prevalence of either H. sativum or Fusarium spp., as indicated by isolations from the crown tissue of wheat. However, as there was a marked tendency at certain stations each year for H. sativum or Fusarium spp. to predominate, it was concluded that certain factors of the environment were more effective than the crop sequence in modifying the relative prevalence of the two fungi mentioned in the crown and root tissue of wheat plants.


1999 ◽  
Vol 50 (6) ◽  
pp. 977 ◽  
Author(s):  
M. P. You ◽  
I. T. Riley ◽  
K. Sivasithamparam ◽  
M. J. Barbetti

Surveys were conducted for annual Medicago spp. (medic) pastures in the grain belt of south-west Western Australia during spring 1996 and winter–spring 1997 to determine the relationship of rainfall, cultural practices, soil and plant nutrients, and seedling survival with severity of root disease and numbers of parasitic nematodes. Medic pasture was sampled on 116 farms. Most pastures consisted of a single medic variety, viz. Serena, Santiago, Cyprus, or Caliph, whereas about 33% of sites had mixed varieties. Regression analyses showed that high rainfall and application of phosphorus fertilisers were correlated with increased severity of rot in medic tap roots. Crop history and medic variety were not related to the level of root rot. Numbers of Pratylenchusin medic roots were not correlated with the level of tap or lateral root rot, medic variety, rainfall, or with the application of insecticide, fertilisers, or herbicides. Soil with relatively high levels of P, NO3-, or Fe was associated with an increased level of tap root rot. Soils with high pH were associated with reduced tap root rot. Soils with relatively high K were related to severe lateral root rot, whereas relatively high levels of P in soil were associated with reduced lateral root rot. Plants with high levels of tap root rot showed low levels of Mg, whilst low levels of Ca and NO3– in tissues were related to high levels of lateral root rot. High levels of tap root rot were associated with relatively high levels of total N, K, and S, Cu, Zn, Mn, and NO3- in plant tissues. Plants with relatively high levels of lateral root rot had relatively high levels of Cu in shoots. Of the 116 annual Medicago pastures sampled, only 1% had adequate Mg content and only 19% had adequate Ca content. However, 83% had higher than adequate levels of Cu, 70% had higher than adequate levels of Mn, and all samples showed more than adequate levels of chloride. Experimental sites of M. polymorpha cv. Serena at 6 farms showed that the percentage survival rate of seedlings was negatively correlated with the severity of tap and lateral root rot in the previous year. These results indicate that in the farms surveyed there is a serious threat to annual medic pastures from root rot fungi. The severity of the disease was partly determined by soil conditions and cultural practices.


2012 ◽  
Vol 26 (4) ◽  
pp. 832-838 ◽  
Author(s):  
Justin D. DeVore ◽  
Jason K. Norsworthy ◽  
Kristofor R. Brye

Glyphosate-resistant Palmer amaranth has become a major problem for cotton producers throughout much of the southern United States. With cotton producers relying heavily on glyphosate-resistant cotton, an alternative solution to controlling resistant Palmer amaranth is needed. A field experiment was conducted during 2009 and 2010 at Marianna, AR, in which a rye cover crop and no cover crop were tested in combination with deep tillage with the use of a moldboard plow and no tillage to determine the impact on Palmer amaranth emergence in cotton. To establish a baseline population, 500,000 glyphosate-resistant Palmer amaranth seeds were placed in a 2-m2area in the middle of each plot and incorporated into the soil, and emergence was evaluated five times during the season. In 2009, both tillage and the cover crop reduced Palmer amaranth emergence in cotton, but the combination of the two reduced emergence 85%. In the second year, only the cover crop reduced Palmer amaranth emergence in cotton, a 68% reduction. Cover crops and deep tillage will not eliminate glyphosate-resistant Palmer amaranth; however, use of these tools will likely reduce the risks of failures associated with residual herbicides along with selection pressure placed on both PRE- and POST-applied herbicides. Additional efforts should focus on the integration of the best cultural practices identified in this research with use of residual herbicides and greater focus on limiting Palmer amaranth seed production and reducing the soil seedbank.


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