Field experiments using the rhabditid nematode Phasmarhabditis hermaphrodita or salt as control measures against slugs in green asparagus

Giant ragweed is a competitive, allergenic weed that persists in agricultural fields and early successional sites. Field experiments were conducted to determine the effects of seed size and seed burial depth on giant ragweed emergence and seed demise. In a seedling emergence experiment, small (< 4.8 mm in diameter) and large (> 6.6 mm in diameter) seeds were buried 0, 5, 10, and 20 cm in fall 1997, and weed emergence was monitored over the next seven growing seasons. A generalized linear mixed model fit to the cumulative emergence data showed that maximum emergence for both seed sizes occurred at the 5-cm burial depth, where probability of emergence was 19% for small seeds and 49% for large seeds. Emergence probability at the 10-cm burial depth was 9% for small seeds and 30% for large seeds, and no seedlings emerged from the 20-cm burial depth. The model predicted that ≥ 98% of total cumulative emergence was completed after four growing seasons for large seeds buried 5 cm, five growing seasons for small seeds buried 5 cm and large seeds buried 10 cm, and seven growing seasons for small seeds buried 10 cm. Seed size and burial treatment effects on seed demise were tested in a second experiment using seed packets. Rates of seed demise were inversely proportional to burial depth, and the percentage of viable seeds remaining after 4 yr ranged from 0% on the soil surface to 19% at the 20-cm burial depth. Some seeds recovered from the 20-cm burial depth were viable after 9 yr of burial. These results, coupled with previous research, suggest that seed size polymorphism facilitates giant ragweed adaptation across habitats and that a combination of no-tillage cropping practices, habitat modification, and timely weed control measures can reduce its active seed bank in agricultural fields by 90% or more after 4 yr.

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Chemical weed management in Brassica rapa var. yellow sarson

Journal of Applied and Natural Science ◽

10.31018/jans.v8i2.855 ◽

2016 ◽

Vol 8 (2) ◽

pp. 663-667

Author(s):

S. K. Das

Keyword(s):

Weed Control ◽

Seed Yield ◽

Weed Management ◽

Field Experiments ◽

Control Measures ◽

Research Station ◽

Control Efficiency ◽

Weed Control Efficiency ◽

Hand Weeding ◽

Level Of Significance

Field experiments were conducted for three years at Pulses and Oilseeds Research Station, Berhampore, Murshidabad, West Bengal, India during rabi 2008, 2009 and 2010 to develop an efficient chemical weed management practice with newer herbicidal molecules in yellow sarson. The experiment was laid out in a randomized block design with three replications having eleven treatments. Experimental results revealed that highest seed yield (1456 kg ha-1) was recorded under the treatment twice hand weeding and lowest with weedy check (910 kg ha-1). Twice hand weeding recorded 60% higher seed yield over weedy check. Application of chemical herbicides significantly improved the seed yield over W0 at 5% level of significance.. Among the chemical weed control measures, application of Pendimathalin @ 1 kg a.i./ha (PE) recorded highest seed yield (1320 kg ha-1) of yellow sarson, which was found at par with application of Pendimathalin @ 1.5 kg a.i./ha (PE), Fluchloralin @ 1.5 kg a.i/ha (PPI) and Clodinafop @ 0.06 kg a.i./ha ( 25-30 DAS). Chemical weed management practices increased the seed yield of yellow sarson by 25.3 to 45.1% over weedy check. Highest weed control efficiency (86.4%) was recorded with hand weeding twice. Significant reduction in the total weed density and total weed dry weight were found with the application of chemical herbicides at 5% level of significance. Among the chemical herbicides Pendimathalin @ 1 kg a.i./ha (PE) recorded highest weed control efficiency (81.7%). Chemical weed control measures increased the total microbial population by 26.5 to 89.4% over weedy check and 6.6 to 59.6% over twice hand weeding and thus proved to be environmentally safe and economic for managing weeds in yellow sarson.

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Early Season Herbicide Applications for Weed Control in Stale Seedbed Soybean (Glycine max)

Weed Technology ◽

10.1017/s0890037x00034266 ◽

1992 ◽

Vol 6 (1) ◽

pp. 36-44 ◽

Cited By ~ 18

Author(s):

Stacey A. Bruff ◽

David R. Shaw

Keyword(s):

Weed Control ◽

Field Experiments ◽

Sandy Loam ◽

Control Measures ◽

Silty Clay ◽

Soybean Yield ◽

Pitted Morningglory ◽

Herbicide Treatments ◽

Hemp Sesbania ◽

Selective Herbicide

Field experiments were conducted in 1989 and 1990 on silty clay and sandy loam soils to evaluate weed control and soybean yield with early-April preplant incorporation of selective herbicides in stale seedbed soybean followed by non-selective weed control measures at planting. Metribuzin applied PPI early followed by chlorimuron POST coupled with either glyphosate or paraquat PRE controlled sicklepod, pitted morningglory, and hemp sesbania to the same extent of that treatment applied PPI at planting. All stale seedbed treatments with POST applications and glyphosate, paraquat, or tillage at planting controlled pitted morningglory over 70%. However, imazaquin or metribuzin applied PPI early without a POST treatment controlled sicklepod and pitted morningglory poorly. Frequently, applying PPI herbicides at planting increased control compared with early PPI applications, but this was overcome by POST treatments. Early stale seedbed applications of metribuzin did not result in more than 60% control of hemp sesbania, whereas metribuzin applied PPI at planting controlled over 85%. However, metribuzin plus chlorimuron controlled hemp sesbania at least 74%, regardless of application timing or tillage method, whereas no imazaquin treatment achieved over 65% control. All stale seedbed herbicide treatments increased soybean yield compared with the untreated stale seedbed check. Selective herbicide treatments with either non-selective herbicide in a stale seedbed program resulted in equivalent yield to PPI at planting treatments most often, except with metribuzin.

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Field Evaluation of Wattle and Silt Fence Ditch Checks

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198121992073 ◽

2021 ◽

pp. 036119812199207

Author(s):

Jaime C. Schussler ◽

Billur Kazaz ◽

Michael A. Perez ◽

J. Blake Whitman ◽

Bora Cetin

Keyword(s):

Confidence Level ◽

Field Experiments ◽

Daily Rainfall ◽

Field Performance ◽

Field Evaluation ◽

Design Guidelines ◽

Control Measures ◽

Retention Rates ◽

Rain Event ◽

Sediment Retention

Erosion and sediment control practices are implemented during construction activities to mitigate downstream effects, but limited field-performance data exists. Field assessments were conducted to evaluate ditch check installations during highway construction in Tama County, Iowa. Data collection included daily rainfall, topographical surveys of sediment deposition, pre- and post-rain event images, and visual observations. Variations to the standard Iowa Department of Transportation silt fence ditch check installation evaluated as part of this study include: (a) upgrading non-reinforced geotextile to a multi-belted, reinforced geotextile (i.e., SF-M1); (b) installing V-shape, as opposed to linear, while incorporating wire reinforcement to support hydrostatic loads placed on the geotextile, inclusion of a weir to facilitate controlled flow discharge, and offsetting the geotextile entrenchment location to improve ground securement (i.e., SF-M2); and (c) installing the dich check as described for SF-M2 substituting slicing for trenching (i.e., SF-M3). The modified wattle installation (i.e., W-M) incorporated a teepee staking configuration to facilitate ground contact, and an excelsior underlay, secured by sod staples, to minimize wattle undercutting. Results from field experiments indicated that sediment retention rates significantly improved for installations of SF-M2 and SF-M3 when compared with the standard installation and SF-M1 at the 85% confidence level, and served as viable control measures in concentrated flow applications. The W-M installation exhibited a statistically significant improvement in sediment retention over the W-S installation at the 95% confidence level. These findings suggest that ditch check performance is a function of specified practice and of installation methods described within regulatory agency specifications and design guidelines.

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Factors affecting the loss of yield of sugar beet caused by beet yellows virus: I. Rate and date of infection; date of sowing and harvesting

The Journal of Agricultural Science ◽

10.1017/s0021859600012041 ◽

1946 ◽

Vol 36 (3) ◽

pp. 151-166 ◽

Cited By ~ 32

Author(s):

Marion A. Watson ◽

D. J. Watson ◽

R. Hull

Keyword(s):

Sugar Beet ◽

Field Experiments ◽

Control Measures ◽

Regression Coefficients ◽

Factors Affecting ◽

Beet Yellows Virus ◽

Experimental Treatments ◽

Spread Of Infection

Field experiments were carried out to measure the effect on the yield and composition of sugar beet of infection with beet yellows virus, and to determine how the effect varies with rate and date of infection and with date of sowing and harvesting of the crop.Control measures designed to prevent spread of infection within experimentally infected plots and introduction of infection from sources outside the experiment, were not completely effective. Consequently the numbers of plants which became infected differed from those prescribed by the experimental treatments. The effects of infection were, therefore, estimated by means of regressions on the numbers of plants observed to become infected on successive dates.After correcting the observed yields for accidental infections by means of the regression coefficients, it was found that the effect of infection on the yield of sugar was linearly related to the rate of infection, i.e. the loss of yield of sugar caused by infection was proportional to the percentage of infected plants. There was no compensation for loss in infected plants by increased growth of healthy neighbours.The effect of infection on yield of sugar decreased linearly with later date of infection, falling to values not significantly different from zero at the date of harvest. The loss of yield caused by infection was therefore approximately proportional to the interval of time between the date of infection, as shown by the appearance of symptoms, and the date of harvest.

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Effects of genotype, environment and fungicide treatment on development of Fusarium head blight and accumulation of DON in winter wheat grain

Czech Journal of Genetics and Plant Breeding ◽

10.17221/1905-cjgpb ◽

2008 ◽

Vol 43 (No. 1) ◽

pp. 16-31 ◽

Cited By ~ 11

Author(s):

V. Šíp ◽

J. Chrpová ◽

L. Leišová ◽

S. Sýkorová ◽

L. Kučera ◽

...

Keyword(s):

Winter Wheat ◽

Fusarium Head Blight ◽

Dna Content ◽

Field Experiments ◽

Fusarium Culmorum ◽

Correlation Coefficients ◽

Control Measures ◽

Head Blight ◽

Fungicide Treatment ◽

Pathogen Dna

Reactions to artificial infection with <i>Fusarium culmorum</i> and (metconazole- or tebuconazole-based) fungicides were studied in nine winter wheat cultivars that were evaluated in field experiments at the location Prague-Ruzyne for four years (2001−2004) for deoxynivalenol (DON) content in grain, pathogen DNA content (Ct) by real-time quantitative PCR, percentage of Fusarium damaged grains (FDG), symptom scores and reductions in grain yield components. All examined traits were highly affected by conditions of experimental years and interactions with cultivars and treatments. Moderately resistant cultivars Arina and Petrus were included in the first homogeneous group in all traits, including the pathogen DNA content. To predict cultivar resistance to Fusarium head blight and accumulation of DON, the examination of the percentage of FDG in different environments appeared to be useful from practical aspects. The pathogen DNA content was significantly related to the content of DON under different conditions, however, the correlation coefficients ranged between 0.42 and 0.92. Different levels of DON could be detected at similar pathogen contents. The higher colonization of grain by the fungus was mostly connected with a strongly reduced amount of DON per pathogen unit (DON/Ct ratio). The fungicide treatment had a significant effect on a reduction in all traits except DON/Ct, but the effects on different traits were not often proportional and they were highly variable in the particular years (range 10−69%) and cultivars (range < 0−60%). While the application of fungicide caused a reduction in DON content in all cultivars, an increase in pathogen content after the application of fungicides was not exceptional. The low fungicide effect on a reduction in pathogen content was connected with higher temperatures (temperature extremes) in a 30-day period of disease development. The efficacy of fungicide treatment for DON was low at high pathogen content and late heading. The use of the collected data to improve control measures is discussed.

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Yield losses in canola in response to blackleg disease

Canadian Journal of Plant Science ◽

10.1139/cjps-2019-0259 ◽

2020 ◽

Vol 100 (5) ◽

pp. 488-494

Author(s):

Yixiao Wang ◽

Stephen E. Strelkov ◽

Sheau-Fang Hwang

Keyword(s):

Disease Severity ◽

Field Experiments ◽

Leptosphaeria Maculans ◽

Economic Benefits ◽

Control Measures ◽

Yield Losses ◽

Blackleg Disease ◽

Brassica Napus L ◽

Moderately Resistant ◽

The Relationship

Blackleg, caused by Leptosphaeria maculans (Desm.) Ces. & De Not., is an important disease of canola (Brassica napus L.) worldwide. In Canada, blackleg is managed mainly by the cultivation of resistant or moderately resistant canola hybrids. Field experiments were conducted in Edmonton, AB, Canada, in 2017 and 2018 to determine the relationship between blackleg disease severity and yield in the moderately resistant canola hybrids ‘73-15RR’ and ‘1950RR’. Blackleg severity was rated on a 0–5 scale, where 0 = no disease and 5 = plant death. Regression analysis showed that relationships between disease severity and pod number and seed yield were best explained by second-degree quadratic equations in all site-years for both cultivars. Percentage yield loss increased by 18%–99% and 26%–86% in plants of ‘73-15RR’ and ‘1950RR’, respectively, with disease severities of 2–5 compared with plants with severities of 0–1. An improved knowledge of the relationship between blackleg severity and yield losses is important for a more accurate evaluation of the agronomic efficacy and economic benefits of control measures.

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Loss of cane and sugar yield resulting from Ceratovacuna lanigera Zehntner damage in cane-growing regions in China

Bulletin of Entomological Research ◽

10.1017/s0007485317000608 ◽

2017 ◽

Vol 108 (1) ◽

pp. 125-129 ◽

Cited By ~ 2

Author(s):

W.F. Li ◽

R.Y. Zhang ◽

Y.K. Huang ◽

C.H. Pu ◽

J. Yin ◽

...

Keyword(s):

Yunnan Province ◽

Field Experiments ◽

Sugar Industry ◽

Sugar Content ◽

Sugar Yield ◽

Control Measures ◽

Effective Control ◽

Sucrose Content ◽

Yield And Quality ◽

Ceratovacuna Lanigera

AbstractCeratovacuna lanigera Zehntner is a major leaf pest of sugarcane. Widely distributed, it affects both the yield and quality of sugarcane in China. This study aimed to assess real yield and sugar yield losses, and the effect of C. lanigera damage on emergence of newly planted and ratoon cane under current production levels. Field experiments were carried out from 2014 to 2016 in Yunnan Province China. At maturity, plants were harvested and weighed to determine yield, and the effect on sugarcane quality and sucrose content analyzed. Real yield decreased by average of 46,185 kg hm−2 (range: 37,545–61,845 kg hm−2) in damaged versus undamaged areas, with an average yield loss rate of 35.9% (28.5–45.7%). Juice yield decreased by an average of 3.01% (2.4–4.13%) and sucrose content by 6.38% (5.48–8.16%). Juice brix decreased by an average of 7.66°BX (6.95–9.05°BX) and juice gravity purity by 12.35% (8.43–19.97%). In contrast, the reducing sugar content increased by an average of 1.21% (1.01–1.3%). Emergence rates of newly planted cane decreased by an average of 26.0% (24.7–27.3%). The emergence number of ratoon cane decreased by 66,834 hm2 (57,429–76,238 hm−2) and relative emergence loss rates of ratoon cane decreased by an average of 57.8% (57.6–58.0%). These findings confirm that C. lanigera damage severely affects sugarcane yield and quality in Yunnan Province. The results will help the implementation of effective control measures, thereby supporting sustainable development of the Chinese sugar industry.

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Can Winged Aphid Abundance Be a Predictor of Cucurbit Aphid-Borne Yellows Virus Epidemics in Melon Crop?

Viruses ◽

10.3390/v12090911 ◽

2020 ◽

Vol 12 (9) ◽

pp. 911

Author(s):

Alexandra Schoeny ◽

Loup Rimbaud ◽

Patrick Gognalons ◽

Grégory Girardot ◽

Pauline Millot ◽

...

Keyword(s):

Field Experiments ◽

Aphis Gossypii ◽

Logistic Models ◽

Aphid Species ◽

Control Measures ◽

Macrosiphum Euphorbiae ◽

Vegetable Crops ◽

Aphid Vectors ◽

The Relationship ◽

Winged Aphid

Aphid-borne viruses are frequent yield-limiting pathogens in open field vegetable crops. In the absence of curative methods, virus control relies exclusively on measures limiting virus introduction and spread. The efficiency of control measures may greatly benefit from an accurate knowledge of epidemic drivers, in particular those linked with aphid vectors. Field experiments were conducted in southeastern France between 2010 and 2019 to investigate the relationship between the epidemics of cucurbit aphid-borne yellows virus (CABYV) and aphid vector abundance. Winged aphids visiting melon crops were sampled daily to assess the abundance of CABYV vectors (Aphis gossypii, Macrosiphum euphorbiae and Myzus persicae) and CABYV was monitored weekly by DAS-ELISA. Epidemic temporal progress curves were successfully described by logistic models. A systematic search for correlations was undertaken between virus variables including parameters µ (inflection point of the logistic curve) and γ (maximum incidence) and aphid variables computed by aggregating abundances on periods relative either to the planting date, or to the epidemic peak. The abundance of A. gossypii during the first two weeks after planting was found to be a good predictor of CABYV dynamics, suggesting that an early control of this aphid species could mitigate the onset and progress of CABYV epidemics in melon crops.

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A critical assessment of the detailed Aedes aegypti simulation model Skeeter Buster 2 using field experiments of indoor insecticidal control in Iquitos, Peru

10.1101/2021.10.03.462931 ◽

2021 ◽

Author(s):

Christian E Gunning ◽

Amy C Morrison ◽

Kenichi W Okamoto ◽

Tom W Scott ◽

Helvio Astete ◽

...

Keyword(s):

Aedes Aegypti ◽

Urban Areas ◽

Population Biology ◽

Field Experiments ◽

Mechanistic Model ◽

Pathogen Transmission ◽

Control Measures ◽

Empirical Results ◽

Fine Grained ◽

Accuracy And Precision

The importance of mosquitoes in human pathogen transmission has motivated major research efforts into mosquito biology in pursuit of more effective vector control measures. Aedes aegypti is a particular concern in tropical urban areas, where it is the primary vector of numerous flaviviruses, including the yellow fever, Zika, and dengue viruses. With an anthropophilic habit, Ae. aegypti prefers houses, human blood meals, and ovipositioning in water-filled containers. We hypothesized that this relatively simple ecological niche should allow us to predict the impacts of insecticidal control measures on mosquito populations. To do this, we use Skeeter Buster 2 (SB2), a stochastic, spatially explicit, mechanistic model of Ae. aegypti population biology. SB2 builds on Skeeter Buster, which reproduced equilibrium dynamics of Ae. aegypti in Iquitos, Peru. Our goal was to predict the response of mosquito populations to perturbations by indoor insecticidal spraying and widespread destructive insect surveys. To evaluate SB2, we conducted two field experiments in Iquitos, Peru: a smaller pilot study in 2013 (S-2013) followed by a larger experiment in 2014 (L-2014). Here, we compare model predictions with (previously reported) empirical results from these experiments. In both simulated and empirical populations, repeated spraying yielded substantial yet temporary reductions in adult densities. The proportional effects of spraying were broadly comparable between simulated and empirical results, but we found noteworthy differences. In particular, SB2 consistently over-estimated the proportion of nulliparous females and the proportion of containers holding immature mosquitoes. We also observed less temporal variation in simulated surveys of adult abundance relative to corresponding empirical observations. Our results indicate the presence of ecological heterogeneities or sampling processes not effectively represented by SB2. Although additional empirical research could further improve the accuracy and precision of SB2, our results underscore the importance of non-linear dynamics in the response of Ae. aegypti populations to perturbations, and suggest general limits to the fine-grained predictability of its population dynamics over space and time.

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