scholarly journals Effects of Tuber Depth and Soil Moisture on Infection of Potato Tubers in Soil by Phytophthora infestans

Plant Disease ◽  
2005 ◽  
Vol 89 (2) ◽  
pp. 146-152 ◽  
Author(s):  
L. D. Porter ◽  
N. Dasgupta ◽  
D. A. Johnson
Keyword(s):  
Soil Moisture ◽  
Phytophthora Infestans ◽  
Soil Type ◽  
Soil Depth ◽  
Soil Surface ◽  
Fine Sand ◽  
Silt Loam ◽  
Potato Plants ◽  
Tuber Infection ◽  
Zoospore Formation

The effects of tuber depth, soil type, and soil moisture on potato tuber infection due to Phytophthora infestans were assessed under greenhouse conditions in soil contained in large pots. Healthy tubers were used to assess infection and were either hand buried in soil at specific depths or naturally formed from potato plants growing in the soil. A spore suspension of P. infestans was chilled to induce zoospore formation and a suspension of resulting zoospores and sporangia were applied to the soil. Soil depth at which tubers became infected was used to determine the extent of spore movement in the soils. Tuber infection significantly decreased with increasing soil depth. Most infected tubers were found at the surface of soil; infection was rare on tubers at 5 cm or deeper in the soil. Amount of tuber infection varied among soil types. Significantly less tuber infection occurred in a Shano silt loam than in medium and fine sands. Only tubers on the soil surface were infected in the Shano silt loam. Depth in soil at which tubers became infected did not differ significantly among Quincy fine sand, Quincy loamy fine sand, and Quincy medium sand. Increased soil moisture did not significantly increase the soil depth at which tuber infection occurred, regardless of the soil type.

scholarly journals The Soil Moisture during Dry Spells Model and Its Verification

Resources ◽  
2020 ◽  
Vol 9 (7) ◽  
pp. 85
Author(s):  
Małgorzata Biniak-Pieróg ◽  
Mieczysław Chalfen ◽  
Andrzej Żyromski ◽  
Andrzej Doroszewski ◽  
Tomasz Jóźwicki
Keyword(s):  
Soil Moisture ◽  
Least Squares Method ◽  
Soil Depth ◽  
Soil Layer ◽  
Atmospheric Precipitation ◽  
Soil Surface ◽  
Model Verification ◽  
Individual Measurement ◽  
Dry Spells ◽  
Dry Spell

The objective of this study was the development and verification of a model of soil moisture decrease during dry spells—SMDS. The analyses were based on diurnal information of the occurrence of atmospheric precipitation and diurnal values of soil moisture under a bare soil surface, covering the period of 2003–2019, from May until October. A decreasing exponential trend was used for the description of the rate of moisture decrease in six layers of the soil profile during dry spells. The least squares method was used to determine, for each dry spell and soil depth, the value of exponent α , which described the rate of soil moisture decrease. Data from the years 2003–2015 were used for the identification of parameter α of the model for each of the layers separately, while data from 2016–2019 were used for model verification. The mean relative error between moisture values measured in 2016–2019 and the calculated values was 3.8%, and accepted as sufficiently accurate. It was found that the error of model fitting decreased with soil layer depth, from 8.1% for the surface layer to 1.0% for the deepest layer, while increasing with the duration of the dry spell at the rate of 0.5%/day. The universality of the model was also confirmed by verification made with the use of the results of soil moisture measurements conducted in the years 2009–2019 at two other independent locations. However, it should be emphasized that in the case of the surface horizon of soil, for which the process of soil drying is a function of factors occurring in the atmosphere, the developed model may have limited application and the obtained results may be affected by greater errors. The adoption of calculated values of coefficient α as characteristic for the individual measurement depths allowed calculation of the predicted values of moisture as a function of the duration of a dry spell, relative to the initial moisture level adopted as 100%. The exponential form of the trend of soil moisture changes in time adopted for the analysis also allowed calculation of the duration of a hypothetical dry spell t, after which soil moisture at a given depth drops from the known initial moisture θ0 to the predicted moisture θ. This is an important finding from the perspective of land use.

scholarly journals Timing Study to Evaluate Product Performance of RH-0345 and Imidacloprid to Suppress Green June Beetle Grubs on a Golf Course Fairway in Lancaster County, Pennsylvania, 1996

1998 ◽  
Vol 23 (1) ◽  
pp. 353-354
Author(s):  
P. R. Heller ◽  
R. Walker
Keyword(s):  
Particle Size ◽  
Soil Moisture ◽  
Soil Temperature ◽  
Soil Type ◽  
Clay Soil ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Silt Loam ◽  
Water Ph ◽  
Loam Soil

Abstract The fairway located in Lancaster County, PA, consisted primarily of perennial ryegrass (80%) and creeping bentgrass (50%). Treatment plots were 7 X 6 ft, arranged in a RCB design and replicated 3 times. Liquid formulations were applied by using a CO2 sprayer with 4 8004VS TeeJet nozzles mounted on a 6-ft boom, operating at 28 psi, and delivering 4 gal/1000 ft2. At the 1st treatment time (4 Jun), the following soil and environmental conditions existed: air temperature, 68° F; soil temperature at 1-inch depth, 64° F; soil temperature at 2-inch depth, 62° F; RH, 67%; amount of thatch, 0.125 inch; soil type, silt loam; soil particle size analysis: 30.7% sand, 61.9% silt, 7.4% clay; soil moisture (oven baked), 28.3%; organic matter, 5.6%; water pH, 7.0; soil pH, 6.1; time of treatment, mid-morning; and overcast skies. The experimental area was irrigated with 0.25 inch of water 3 fir after treatment. At the 2nd treatment time (15 Jul), the following soil and environmental conditions existed: air temperature, 78° F; soil temperature at 1-inch depth, 74° F; soil temperature at 2-inch depth, 75° F; RH, 75%; amount of thatch, 0.0625-0.125 inch; soil type; silt loam; soil particle size analysis: 30.7% sand, 61.9% silt, 7.4% clay; soil moisture (oven baked), 37.7%; organic matter, 7.2%; water pH, 7.0; soil pH, 5.9; time of treatment, mid-morning; and cloudy skies. The experimental area was irrigated with 0.25 inch of water immediately after product dried. A the 3rd treatment time (12 Aug), the following soil and environmental conditions existed: air temperature, 65° F; soil temperature at 1-inch depth, 69° F; soil temperature at 2-inch depth, 69° F; RH, 90%; amount of thatch, 0.0625-0.125 inch; soil type, silt loam; soil particle size analysis: 30.7% sand, 61.9% silt, 7.4% clay; soil moisture (oven baked), 40.0%; organic matter, 5.7%; water pH, 7.0; soil pH, 6.5; time of treatment, early morning; and cloudy skies. The experimental area was irrigated with 0.25 inch of water immediately after product dried. Post-treatment counts were made on 29 Aug. The total number of green of June beetle larvae flushed to the surface following an application of Sevin SL over a 24-hr observation interval was recorded from each replicate.

Population dynamics of Paratylenchus nanus in soil under pasture: 1. Aggregation and abiotic factors

Nematology ◽  
2001 ◽  
Vol 3 (2) ◽  
pp. 187-197 ◽  
Author(s):  
Richard Watson ◽  
Nigel Bell
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Soil Depth ◽  
Abiotic Factors ◽  
Soil Phosphorus ◽  
Silt Loam ◽  
Plant Abundance ◽  
Grazed Pasture ◽  
Loam Soil ◽  
Accumulated Temperature

AbstractParatylenchus nanus populations were assessed by seasonal and monthly sampling of grazed pasture on silt loam soil in Waikato, New Zealand. The data were used to investigate P.nanus aggregation and relationships with abiotic factors, including soil temperature, rainfall, soil moisture and soil nutrients. P.nanus was more abundant at 10-20 than 0-10 cm soil depth and populations were greatest in summer. Aggregation declined from spring through to winter. P.nanus populations were positively correlated with soil temperature and negatively with soil moisture (seasonally) and rainfall (monthly). Monthly P. nanus abundance was also positively correlated with a combination of accumulated temperature and rainfall. On single occasions, soil phosphorus and nitrogen were significantly negatively correlated with P.nanus populations, and it is suggested that these associations were mediated through host plant abundance.

Effect of soil type and rainfall on dicyandiamide concentrations in drainage from lysimeters

Soil Research ◽  
2012 ◽  
Vol 50 (1) ◽  
pp. 67 ◽  
Author(s):  
Mark Shepherd ◽  
Justin Wyatt ◽  
Brendon Welten
Keyword(s):  
Nitrate Leaching ◽  
Soil Type ◽  
Preferential Flow ◽  
Sandy Loam ◽  
Nitrification Inhibitor ◽  
Soil Surface ◽  
Drainage Water ◽  
Silt Loam ◽  
Combining Data ◽  
Dispersive Flow

The nitrification inhibitor dicyandiamide (DCD) is mobile in drainage water, which has implications for its effectiveness in reducing nitrate leaching from urine patches. Lysimeters had been used to investigate the effect of soil type (clay, silt loam, or sandy loam) and precipitation (target ~1140 or 2280 mm/year) on the effectiveness of DCD to decrease nitrate leaching. This paper reports the associated effects on DCD in drainage water. DCD was applied in May and July at a rate of 10 kg/ha, and natural rainfall was supplemented with irrigation to ensure that the target precipitation was achieved for each treatment. The experiment was undertaken twice. The pattern of DCD concentrations in drainage water suggested that movement of DCD in the silt loam and sandy loam soils was typical of convective–dispersive flow. Although there was some preferential flow of DCD from the soil surface to depth in the clay soil, DCD concentration profiles suggested that the main transport mechanism was also by convective–dispersive flow. There were significant soil-type and precipitation effects on DCD leaching (P < 0.05). The soil-type effect could be attributed to differences in drainage volume between soils. Combining data from the two experimental years, DCD leaching losses ranged from 12 to 46% of applied, with annual drainage in the range 422–1292 mm. DCD was detected in drainage up to 15 months after application, demonstrating the longevity of the compound. The experiment demonstrates that leaching of DCD on all of the soil types tested can be substantial under high rainfall. This is likely to have implications for the effectiveness of DCD to decrease nitrogen losses from urine patches under such rainfall conditions, as well as being a source of nitrogen itself.

scholarly journals Survival of Sporangia of New Clonal Lineages of Phytophthora infestans in Soil Under Semiarid Conditions

Plant Disease ◽  
2007 ◽  
Vol 91 (7) ◽  
pp. 835-841 ◽  
Author(s):  
L. D. Porter ◽  
D. A. Johnson
Keyword(s):  
Phytophthora Infestans ◽  
Survival Curve ◽  
Fine Sand ◽  
Soil Types ◽  
Silt Loam ◽  
Columbia Basin ◽  
The World ◽  
Dry Soil ◽  
Resistant Genotypes ◽  
Semiarid Conditions

Currently, there is no information on the viability of sporangia in soil of the new metalaxyl-resistant genotypes of Phytophthora infestans in the semiarid Columbia Basin of Washington and potato-growing regions throughout the world. Sporangia of metalaxyl-resistant US-8 and US-11 clonal lineages of P. infestans survived a maximum of 23 to 30 days in a Shano silt loam and a Quincy loamy fine sand. There were no significant differences between soil types in area under the spore survival curve (AUSSC) in two trials, however, sporangia of P. infestans in the Quincy sand had a significantly greater mean maximum days of sporangia survival (MDSS) than did the Shano silt loam in one of two trials. AUSSC and MDSS were significantly greater (P < 0.05) for sporangia in wet soil than in dry soil under shaded conditions. Mean AUSSC and MDSS significantly decreased (P < 0.01) under nonshaded conditions versus shaded conditions. Three metalaxyl-resistant isolates (two US-8 and one US-11) of P. infestans did not significantly differ (P < 0.05) in AUSSC and MDSS.

Seed burial by tillage promotes field recruitment of false cleavers (Galium spurium) and catchweed bedstraw (Galium aparine)

Weed Science ◽  
2005 ◽  
Vol 53 (5) ◽  
pp. 578-585 ◽  
Author(s):  
Danielle J. Reid ◽  
Rene C. Van Acker
Keyword(s):  
Soil Moisture ◽  
Bulk Density ◽  
Great Plains ◽  
Field Experiments ◽  
Soil Depth ◽  
Soil Surface ◽  
Northern Great Plains ◽  
Galium Aparine ◽  
Tillage Operation ◽  
Galium Spurium

False cleavers and catchweed bedstraw are problematic weeds of field crops in high-latitude regions of the northern Great Plains of North America. The abundance of these species has been increasing in areas of greater tillage intensity and frequency. Field experiments were established over 4 site-yr in Manitoba, Canada, and results indicated that the recruitment of false cleavers and catchweed bedstraw was strongly promoted by a single shallow tillage operation with a sweep cultivator in the spring. Percent recruitment levels in 2001 (pooled over sites) were 17 and 46% for the untilled and tilled treatments, respectively. In 2002, the percent recruitment levels for the untilled and tilled treatments, respectively, were 28 and 38% for the Komarno site and 13 and 28% for the Petersfield site. Only a few and minor differences in microsite conditions (soil temperature, soil moisture, and bulk density) resulted from the single spring tillage pass. The single tillage pass caused a significant relocation of simulated seeds (plastic beads) to below the soil surface and deeper into the soil profile (2–4 cm). Mean bulk density and volumetric soil moisture increased significantly with soil depth. The results of this study suggest that the positive effect of tillage on cleavers recruitment was not due to the effect of tillage on microsite conditions per se. Rather, the vertical redistribution of seed by tillage moved these seeds to a place in which the microsite conditions differed from those on the surface and were more favorable for recruitment. False cleavers and catchweed bedstraw recruitment is clearly promoted by tillage (even minor tillage) under field conditions, and farmers might be able to limit recruitment by limiting spring tillage.

scholarly journals Preemergence Infection of Potato Sprouts by Phytophthora infestans in the Highland Tropics of Ecuador

Plant Disease ◽  
2008 ◽  
Vol 92 (4) ◽  
pp. 569-574 ◽  
Author(s):  
Peter Kromann ◽  
Arturo Taipe ◽  
Jorge L. Andrade-Piedra ◽  
Lisa Munk ◽  
Gregory A. Forbes
Keyword(s):  
Disease Management ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Seed Potato ◽  
Soil Surface ◽  
Potato Tubers ◽  
Potato Plants ◽  
Management Approaches

Experiments were conducted to determine whether preemergence infection of potato sprouts by Phytophthora infestans occurs in the highland tropics of Ecuador. In three separate experiments in the field, P. infestans was identified on the preemerged sprouts of 49, 5, and 43% of tubers, respectively, which had been removed from soil prior to emergence. Tubers had been planted within 10 m of approximately 300-m2 plots with mature potato plants severely infected with late blight. Infection potential of potato sprouts also was evaluated in the greenhouse by applying 10-ml sporangial suspensions (50 and 250 sporangia/ml) daily for 10 days to the soil surface of pots planted with sprouted seed potato tubers. The daily inoculation rate of 50 sporangia/ml (15.9 × 103 sporangia/m2) resulted in sprout infection in 100% of inoculated pots and roughly corresponded to the sporangial deposition accumulated over 24 h in the field. Deposition had been measured at 1 m from a severely infected potato plot. Our study demonstrated the potential for preemergence infection of potato sprouts by P. infestans in the highlands of Ecuador, where year-round aerial inoculum is present. Preemergence infection is consistent with high levels of disease sometimes seen in recently emerged potato fields. These experiments indicate a need to reconsider disease management approaches.

scholarly journals Evaluating Seed-covering Devices and Presswheels for Directly Seeding Mustard and Cabbage

1998 ◽  
Vol 8 (1) ◽  
pp. 74-77
Author(s):  
Regina P. Bracy ◽  
Richard L. Parish
Keyword(s):  
Soil Moisture ◽  
Soil Type ◽  
Sandy Loam ◽  
Silt Loam ◽  
Fine Sandy Loam ◽  
Brassica Crops ◽  
Direct Seeded ◽  
Plant Emergence ◽  
Plant Stand ◽  
Moisture Conditions

Stands of brassica crops obtained with precision seeders are sometimes inadequate or nonuniform. Although several types of covering devices and presswheels are available from precision seeder manufacturers, the effects of covering devices and presswheels on plant emergence of direct-seeded Brassica crops have not been determined. In Spring and Fall 1996, six crops of mustard [Brassica juncea (L.) Czerniak] and four crops of cabbage (Brassica oleracea L. capitata group) were direct seeded with a precision belt seeder using four covering devices and four rear presswheels. All of the covering devices and presswheels evaluated were adequate for direct seeding mustard and cabbage under the soil moisture conditions and soil type (silt loam or fine sandy loam) found in these experiments. Although poor stands were obtained with all seed covering devices and presswheels when 7.8 inches (199 mm) of rain occurred within 3 days of planting, plant stand of cabbage was greater when the paired arm device was used than with drag-type or no covering devices.

LYSIMETERS WITH RAINFALL AND SOIL WATER CONTROL

1971 ◽  
Vol 2 (2) ◽  
pp. 79-92 ◽  
Author(s):  
K. J. KRISTENSEN ◽  
H. C. ASLYNG
Keyword(s):  
Soil Moisture Content ◽  
Soil Depth ◽  
Irrigation System ◽  
Drainage System ◽  
Soil Surface ◽  
Trickle Irrigation ◽  
Water Control ◽  
Radiation Equipment ◽  
Different Depths ◽  
Growth Experiments

The lysimeter installation described comprises 36 concrete tanks each with a soil surface of 4 m2. The installation is useful for plant growth experiments under natural conditions involving different treatment combined with various controlled water supplies. The ground installation is at least 20 cm below the soil surface and tillage can be done with field implements. The lysimeter tanks are provided with a drainage system which can drain the soil at the bottom (100 cm depth) to a tension of up to 100 cm. A constant ground-water table at less than 100 cm soil depth can also be maintained. The soil moisture content at different depths is determined from an underground tunnel by use of gamma radiation equipment in metal tubes horizontally installed in the soil. Rainfall is prevented by a movable glass roof automatically operated and controlled by a special rain sensor. Water is applied to the soil surface with a special trickle irrigation system consisting of a set of plastic tubes for each lysimeter tank and controlled from the tunnel. Fertilizers in controlled amount can be applied with the irrigation water.

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