Effects of irrigation regimes on powdery scab disease and yield of potatoes

1986 ◽  
Vol 26 (6) ◽  
pp. 745 ◽  
Author(s):  
PA Taylor ◽  
SP Flett ◽  
RFde Boer ◽  
D Marshall
Keyword(s):  
Large Scale ◽  
Field Experiments ◽  
Field Trials ◽  
Powdery Scab ◽  
Infested Soil ◽  
Spongospora Subterranea ◽  
Potato Tubers ◽  
Potato Plants ◽  
Tuber Set ◽  
Large Scale Field

The period of susceptibility of potato tubers to powdery scab (Spongospora subterranea) was studied by inoculating potato plants with spores, or by watering plants in infested soil, at different stages of plant development in greenhouse conditions. Maximum susceptibility began about 1 week before the stage when 50% of stolons had swollen to at least 5-mm diameter (tuber set), and ended 3-4 weeks later. With holding irrigation water during this period reduced the severity of powdery scab by 65-75% in field experiments in 1981-82 and 1982-83, but had no apparent effect on disease severity in 3 out of 6 large-scale field trials during 1984-85.

scholarly journals Evaluation of Effects of Chemical Soil Treatments and Potato Cultivars on Spongospora subterranea Soil Inoculum and Incidence of Powdery Scab and Potato Mop-Top Virus in Potato

Plant Disease ◽  
2020 ◽  
Vol 104 (11) ◽  
pp. 2807-2816
Author(s):  
Yuan Zeng ◽  
Ana Cristina Fulladolsa ◽  
Andrew M. Cordova ◽  
Patrick O’Neill ◽  
Stewart M. Gray ◽  
...  
Keyword(s):  
Field Experiments ◽  
Potato Cultivar ◽  
Potato Cultivars ◽  
Powdery Scab ◽  
Infested Soil ◽  
Spongospora Subterranea ◽  
Pathogen Population ◽  
Chemical Treatments ◽  
Soil Inoculum ◽  
Potato Mop Top Virus

Spongospora subterranea is a soilborne plasmodiophorid that causes powdery scab in potato. It also transmits potato mop-top virus (PMTV), which causes necrotic arcs (spraing) in potato tubers. Three field experiments were conducted in naturally S. subterranea-infested soil to investigate the effects of two chemicals, Omega 500F (fluazinam) and FOLI-R-PLUS RIDEZ (biological extract), on powdery scab, PMTV, and changes in S. subterranea inoculum with six different potato cultivars. The efficacy of soil treatment with these two chemicals on tuber lesions, root galling, and pathogen population was also assessed in greenhouse trials. The chemical treatments did not reduce powdery scab, root gall formation, or S. subterranea inoculum in the field or greenhouse trials. Postharvest S. subterranea soil inoculum in fields varied across farms and among potato cultivars but the pathogen population consistently increased by the end of the growing season. The evaluated russet cultivars were more tolerant to powdery scab than the yellow- or red-skinned cultivars but all were susceptible to PMTV. In the field, powdery scab indices and soil inoculum changes were positively correlated, while postharvest S. subterranea inoculum was positively correlated with root galling in both greenhouse trials. Powdery scab and PMTV occurred in noninoculated potting mix, indicating that peat-based potting mix is a source for both pathogens. These results demonstrate that chemical management methods currently used by farmers are ineffective, that S. subterranea and PMTV in potting mix can cause severe epidemics in greenhouses, and that potato cultivar choices impact inoculum increases in soil.

scholarly journals Reduced Dosage of Methyl Bromide for Controlling Verticillium Wilt of Potato in Experimental and Commercial Plots

Plant Disease ◽  
1997 ◽  
Vol 81 (5) ◽  
pp. 469-474 ◽  
Author(s):  
A. Gamliel ◽  
A. Grinstein ◽  
Y. Peretz ◽  
L. Klein ◽  
A. Nachmias ◽  
...  
Keyword(s):  
Verticillium Wilt ◽  
Methyl Bromide ◽  
Large Scale ◽  
Field Experiments ◽  
Tuber Yield ◽  
Total Yield ◽  
Effective Control ◽  
Large Scale Field ◽  
Commercial Applications

The use of gas-impermeable films to reduce the dosage of methyl bromide (MB) required to control Verticillium wilt in potatoes was examined in field experiments, conducted in soils naturally infested with Verticillium dahliae. The incidence and severity of Verticillium wilt were significantly reduced (by 74 to 94%) by fumigation with MB at 50 g/m2 under standard low density polyethylene (LDPE) or at 25 g/m2 under gas-impermeable films. Fumigation at 25 g/m2 under LDPE was less effective. Disease severity was inversely correlated (r2 = 0.89 to 0.91) with chlorophyll content in the leaves. Fumigation also reduced (by 89 to 100%) stem colonization by the pathogen. Potato yield in the fumigated plots was significantly higher (26 to 69%), than in their nonfumigated counterparts, and was inversely correlated with disease index (r2 = 0.69 to 0.9). The percentage of high-value tubers (above 45 g) was 52 to 56% of total yield in the fumigated plots as compared with 32 to 40% in the nonfumigated controls. Thus, fumigation also improved the commercial quality of tuber yield. Effective control of V. dahliae and yield increases following MB fumigation at the recommended dosage or at a reduced dosage with gas-impermeable films was also observed in a consecutive crop. These results were verified in a large-scale field experiment using commercial applications, further demonstrating the feasibility of reducing MB dosages under farm conditions, without reducing its effectiveness in terms of disease control and yield improvement.

Large-Scale Field Trials on Dense Vapour Dispersion

1985 ◽  
pp. 179-189 ◽  
Author(s):  
J. McQuaid ◽  
B. Roebuck ◽  
D. G. Wilde
Keyword(s):  
Large Scale ◽  
Field Trials ◽  
Scale Field ◽  
Large Scale Field

scholarly journals Photogrammetric avalanche volume measurements at Vallée de la Sionne, Switzerland

2001 ◽  
Vol 32 ◽  
pp. 141-146 ◽  
Author(s):  
Juauien Vallet ◽  
Urs Gruber ◽  
François Dufour
Keyword(s):  
Large Scale ◽  
Field Experiments ◽  
Test Site ◽  
Deposition Zone ◽  
Before And After ◽  
Large Scale Field ◽  
Volume Measurements ◽  
Snow Distribution ◽  
The Mean ◽  
The Difference

AbstractDuring winter 1999 three large avalanche events were triggered by explosives at SLF’s avalanche test site, Vallée de la Sionne, canton Valais, Switzerland. One important goal of these large-scale field experiments was to measure the release and deposition volumes of avalanches by photogrammetric methods. In this paper, the photogrammetric measurements of all three avalanches are summarized. For one avalanche event it was possible to realize the whole measuring procedure as planned, and to obtain volume measurements before and after the avalanche triggering In the other two avalanche events, the photographs before the triggering of the avalanche failed. Nevertheless the photographs taken after the avalanche provide valuable information on the fracture depth at the fracture line. The mean fracture depth of the largest avalanche was about 2.10 m, varying between 1 and 3.5 m over a width of > 1000 m. The total volume of the deposition of all three avalanche events was about 1300 000 m3. The deposits are distributed over a length of > 1000 m with depths up to 30 m. The difference between the released and deposited volumes proved that avalanches entrain a large amount of snow along the avalanche track. Furthermore, the snow distribution in the deposition zone provides important information about the behaviour of a dense flowing avalanche in the runout zone.

scholarly journals Off-Site Lime Stabilisation as an Option to Treat Pit Latrine Faecal Sludge for Emergency and Existing On-Site Sanitation Systems

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Wilson Greya ◽  
Bernard Thole ◽  
Catherine Anderson ◽  
Flavius Kamwani ◽  
Jan Spit ◽  
...  
Keyword(s):  
Large Scale ◽  
Buffer Capacity ◽  
Hydrated Lime ◽  
Field Trials ◽  
Small Scale ◽  
E Coli ◽  
Scale Field ◽  
Large Scale Field ◽  
Sanitation Systems ◽  
Faecal Sludge

Off-site lime stabilisation for treating faecal sludge was assessed by undertaking small-scale (35 L) and large-scale (600 L) field trials in Blantyre, Malawi. Hydrated lime was dosed to maintain pH 10, pH 10.5, pH 11, pH 11.5, and pH 12 depending on the buffer capacity of the faecal sludge in the four replica small-scale field trials. Significant reduction of E. coli to below the detection limit of 104 CFU/100 mL within 1 hour of treatment was reported for pH > 11. Based on the small-scale findings, large-scale field trials were conducted and greater than 3 log removal of E. coli was observed under pH 12 conditions. Therefore, based on the study, off-site lime stabilisation by dosing lime in the range of 10–35% w/w (dry solid basis), depending on the buffer capacity and solids content of the sludge to maintain pH > 11, can be used to sanitise faecal sludge during emergencies, as well as for existing on-site sanitation systems.

Pattern recognition of cardoon oil from different large-scale field trials

2018 ◽  
Vol 118 ◽  
pp. 236-245 ◽  
Author(s):  
Suzana Ferreira-Dias ◽  
Jorge Gominho ◽  
Isabel Baptista ◽  
Helena Pereira
Keyword(s):  
Pattern Recognition ◽  
Large Scale ◽  
Field Trials ◽  
Scale Field ◽  
Large Scale Field

Discussion Networks in Political Decision Making

2020 ◽  
Author(s):  
Ian Shapiro ◽  
Steven Richardson ◽  
Scott McClurg ◽  
Anand Sokhey
Keyword(s):  
Voting Behavior ◽  
Large Scale ◽  
Field Experiments ◽  
Political Discussion ◽  
Cross Sectional ◽  
Attitude Polarization ◽  
Political Networks ◽  
Research Designs ◽  
Large Scale Field ◽  
Complete Networks

Decades of work have illuminated the influence interpersonal networks exert on voting behavior, political participation, the acquisition of political knowledge, tolerance, ambivalence, and attitude polarization. These central findings have largely been grounded in examinations of political discussion and have remained robust to measurement differences of key concepts like disagreement, various data collection methods, and multiple research designs ranging from the cross-sectional to large-scale field experiments. By comparison, scholars understand considerably less about individuals’ motivation to approach their social contacts when it comes to politics, and about why networks produce the outcomes that they do; this calls researchers to reflect on and revisit previous research, but also to consider new paths of research. Although there is a growing body of promising work focused on “whole,” or complete, networks, much can also be gained by better integrating social psychology into the study of egocentric, or “core,” political networks. Answering these (and other) questions will help connect current findings, emerging methods, and nascent theory. Such connections should advance dialogues between research on group influence, discussion networks, and individual political behavior.

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