Yield loss and management of downy mildew on field pea in Alberta, Canada

Downy mildew of collard occurs frequently in the southeastern United States, and fungicides have become an essential part of economical control strategies for the disease. Fungicides were evaluated in 2007 and 2008 either alone or combined with a reduced rate (2 pt/acre) of potassium phosphite. Two formulations of potassium phosphite also were tested alone at the full rate (4 pt/acre). Presidio, Presidio plus Pro-Phyt (2007) or K-Phite (2008), K-Phite, Amistar plus ProPhyt, and Aliette reduced downy mildew severity at the final rating and also reduced AUDPC over the two years. Presidio plus potassium phosphite and Amistar plus ProPhyt increased the weight of healthy leaves and stems over the water control and also increased economic return calculated after fungicide and other production costs were subtracted from the crop value. The yields with Ranman, Sonata, and Presidio applied in combination with potassium phosphite were 16% greater than with the fungicides applied alone. Potassium phosphite may be useful in a tank-mix with other fungicides applied to collard to prevent yield loss to downy mildew. Accepted for publication 7 July 2010. Published 23 August 2010.

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Effect of mancozeb on the control of mycosphaerella blight of field pea

Canadian Journal of Plant Science ◽

10.4141/p99-085 ◽

2000 ◽

Vol 80 (2) ◽

pp. 403-406 ◽

Cited By ~ 14

Author(s):

T. D. Warkentin ◽

A. G. Xue ◽

D. W. McAndrew

Keyword(s):

Yield Loss ◽

Foliar Application ◽

Genetic Resistance ◽

Similar Efficacy ◽

Field Trials ◽

Field Pea ◽

Mycosphaerella Pinodes ◽

Western Canada ◽

Flowering Stage ◽

Plot Design

Mycosphaerella blight (MB) [Mycosphaerella pinodes (Berk. & Blox.)Vestergr.] causes substantial yield loss to field pea in western Canada in most seasons and is a disease for which genetic resistance is lacking. The objective of this research was to evaluate the effectiveness of foliar application of mancozeb for the control of MB of field pea. Field trials of split-plot design were conducted at two sites per year from 1996 to 1998 in southern Manitoba, with cultivars as main-plots and fungicide treatments as sub-plots. In most site-years, a single application of mancozeb at the early flowering stage was effective in reducing MB severity and in increasing yield. Mancozeb had similar efficacy to chlorothalonil, the only currently registered fungicide for control of MB in field pea. The beneficial effect of both fungicides was greater for the highly MB susceptible cultivars AC Tamor and Carrera than the moderately MB susceptible cultivar Radley. Key words: Pisum sativum, field pea, mycosphaerella blight, mancozeb, chlorothalonil

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Challenges with Managing Disease Complexes during Application of Different Measures Against Foliar Diseases of Field Pea

Plant Disease ◽

10.1094/pdis-07-20-1470-re ◽

2020 ◽

Author(s):

Martin John BARBETTI ◽

Tanveer N Khan ◽

Ian Pritchard ◽

Jay Ram Lamichhane ◽

Jean-Noël Aubertot ◽

...

Keyword(s):

Downy Mildew ◽

Seed Yield ◽

Management Practices ◽

Plant Density ◽

Ascochyta Blight ◽

Early Time ◽

Field Pea ◽

Foliar Disease ◽

Foliar Pathogens ◽

Disease Complexes

Studies were undertaken across five field locations in Western Australia to determine the relative changes in disease severity and subsequent field pea yield from up to four foliar pathogens associated with a field pea foliar disease complex (viz. Didymella, Phoma, Peronospora, Septoria), across four different pea varieties sown at three different times and at three different densities. Delaying sowing of field pea significantly (P<0.05) reduced severity of Ascochyta blight (all five locations) and Septoria blight (1 location), increased severity of downy mildew (4 locations), but had no effect on seed yield. In relation to Ascochyta blight severity at 80 days after sowing, at all locations the early time of sowing had significantly (P<0.05) more severe Ascochyta blight than the mid and late times of sowing. Increasing actual plant density from 20-25 plants m-2 to 58-78 plants m-2 significantly (P<0.05) increased the severity of the Ascochyta blight (4 locations) and downy mildew (1 location), and increased seed yield at four locations irrespective of sowing date and three locations irrespective of variety. Compared with varieties Dundale, Wirrega and Pennant, variety Alma showed significantly (P<0.05) less severe Ascochyta blight (1 location), downy mildew (1 location) and Septoria blight (1 location). Grain yield was highest for the early time of sowing at three locations. Varieties Alma, Dundale and Wirrega significantly (P<0.05) out yielded Pennant at four locations. The percentage of isolations of individual Ascochyta blight pathogens at 80 days after the first time of sowing varied greatly, with Didymella ranging 25-93% and Phoma from 6- 23% across the five field locations. This fluctuating nature of individual pathogen types and proportions within the Ascochyta blight complex, along with variation in occurrence of Peronospora and Septoria, highlights the challenges to understand and manage the complexities of co-occurring different foliar pathogens of field pea. While the search for more effective host resistance continues, there is a need for and opportunities from further exploring and exploiting cultural management approaches focussing on crop sequence diversification, intercropping, manipulating time of sowing and stand density, and application of improved seed sanitation and residue/inoculum management practices. We discuss the constraints and opportunities towards overcoming the challenges associated with managing foliar disease complexes in field pea.

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Field Pea and Lentil Tolerance to Interrow Cultivation

Weed Technology ◽

10.1017/wet.2017.90 ◽

2017 ◽

Vol 32 (2) ◽

pp. 205-210 ◽

Cited By ~ 1

Author(s):

Katherine A. Stanley ◽

Steven J. Shirtliffe ◽

Dilshan Benaragama ◽

Lena D. Syrovy ◽

Hema S. N. Duddu

Keyword(s):

Weed Control ◽

Field Experiments ◽

Yield Loss ◽

Growing Season ◽

Field Pea ◽

Crop Damage ◽

Growth Stages ◽

Row Crops ◽

Narrow Row ◽

Mechanical Weed Control

AbstractInterrow cultivation is a selective, in-crop mechanical weed control tool that has the potential to control weeds later in the growing season with less crop damage compared with other in-crop mechanical weed control tools. To our knowledge, no previous research has been conducted on the tolerance of narrow-row crops to interrow cultivation. The objective of this experiment was to determine the tolerance of field pea and lentil to interrow cultivation. Replicated field experiments were conducted in Saskatchewan, Canada, in 2014 and 2015. Weekly cultivation treatments began at the 4-node stage of each crop, continuing for 6 wk. Field pea and lentil yield linearly declined with later crop stages of cultivation. Cultivating multiple times throughout the growing season reduced yield by 15% to 30% in both crops. Minimal yield loss occurred when interrow cultivation was conducted once at early growth stages of field pea and lentil; however, yield loss increased with delayed and more frequent cultivation events.

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Influence of oxathiapiprolin on preinfectional and early infection stages of Plasmopara halstedii, downy mildew of the sunflower

Plant Protection Science ◽

10.17221/112/2019-pps ◽

2020 ◽

Vol 56 (No. 2) ◽

pp. 83-91

Author(s):

Otmar Spring ◽

Javier Gómez-Zeledón

Keyword(s):

Life Cycle ◽

Downy Mildew ◽

Yield Loss ◽

Developmental Stages ◽

Early Infection ◽

Pure Compound ◽

Plasmopara Halstedii ◽

Low Concentrations ◽

Fungicide Activity ◽

Leaf Disks

Oxathiapiprolin is a recently introduced fungicide with particular activity against hemibiotrophic and biotrophic oomycetes. For Plasmopara halstedii, the downy mildew of the sunflower, no detailed studies for the activity of the pure compound on the preinfectional and early infection stages in which the fungicide could most effectively interfere with the life cycle of the pathogen have been reported. The fungicide was shown to be active against all stages of the pathogen starting from the release of the zoospores to the development of the mycelia and the formation of the sporangia. Differences in the sensitivity of the different developmental stages are in accordance with the suggested mechanism of the fungicide activity which targets sterol-binding proteins. The experiments showed that, in preventive treatments against very sensitive stages of the pathogen (such as germination of spores), extremely low concentrations of less than 1 ng/mL can completely protect the plants. Coating the seeds with oxathiapiprolin successfully prevented the seedlings from soil-borne infections. This is of particular importance in sunflower cultivation, because wind-borne infections on plants are much rarer and less harmful than soil-borne infections, which usually become systemic and lead to complete yield loss. The curative effects of oxathiapiprolin were shown on the leaf disks as well as on the infected young plants. However, this seems to be less important in sunflower cultivation than, for instance, in viticulture, because spraying sunflowers in the field after the germination of the seeds is uncommon (except in the ornamental cultivation of cut sunflowers).

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Analysis of Downy Mildew Infection of Field Pea Varieties Using the Logistic Model

Journal of Plant Protection Research ◽

10.2478/v10045-012-0038-z ◽

2012 ◽

Vol 52 (2) ◽

pp. 240-246 ◽

Cited By ~ 2

Author(s):

Ewa Bakinowska ◽

Wiesław Pilarczyk ◽

Agnieszka Osiecka ◽

Kazimierz Wiatr

Keyword(s):

Downy Mildew ◽

Logistic Model ◽

Field Trials ◽

Field Pea ◽

Model Parameters ◽

Scoring Method ◽

Multinomial Data ◽

Time Period ◽

Resistant Varieties ◽

Evaluation Of Data

Analysis of Downy Mildew Infection of Field Pea Varieties Using the Logistic ModelThe logistic model is commonly used for analysis of discrete, multinomial data. Such a model was used for the statistical evaluation of data concerning infection of field pea varieties by downy mildew, in two series of field trials. Each series consisted of experiments performed in locations spread over the whole of Poland in the time period from 2002 to 2005. Varieties cultivated on light soils were compared in the first series, and varieties cultivated on rich soils in the second. The most resistant varieties were identified (Sokolik - light soils, Terno - rich soils) and significant differences among varieties were detected. Estimators of model parameters were found using the Fisher scoring method implemented inlogistic glmprocedure of the SAS system.

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Texas Has a New Pathotype of Peronosclerospora sorghi, the Cause of Sorghum Downy Mildew

Plant Disease ◽

10.1094/pd-89-0529a ◽

2005 ◽

Vol 89 (5) ◽

pp. 529-529 ◽

Cited By ~ 17

Author(s):

T. Isakeit ◽

J. Jaster

Keyword(s):

Relative Humidity ◽

Downy Mildew ◽

Yield Loss ◽

Genetic Resistance ◽

Conidial Suspension ◽

Peronosclerospora Sorghi ◽

Sorghum Downy Mildew ◽

Local Lesions ◽

Systemic Symptoms ◽

Minor Disease

Three pathotypes of Peronosclerospora sorghi were known to occur in Texas as of 1980, with pathotype 3 (P3) predominant on sorghum (Sorghum bicolor) grown in the Upper Coast area. Following the use of hybrids resistant to P3, combined with metalaxyl or mefenoxam seed treatment, sorghum downy mildew (SDM) became a minor disease in Texas until the occurrence of a widespread outbreak caused by a P3 strain resistant to metalaxyl and mefenoxam in Wharton County in 2001 (2). During July 2004, <1% of plants in a commercial field in Wharton County planted to two Pioneer Brand P3-resistant hybrids had white stripes on the leaves and leaf shredding typical of systemic SDM. To obtain inoculum for pathogenicity studies, several infected plants were removed from the field and transplanted to pots for growth in a greenhouse. Systemically infected leaves suitable for inoculum production subsequently developed from tillers. Conidia were collected from leaves using a tiered temperature system (1). One-week-old seedlings of 10 sorghum lines used as pathotype differentials for Texas were sprayed until runoff with a conidial suspension (8 × 104 per ml) and incubated for 24 h at 20°C and 100% relative humidity. Seedlings were grown for 6 days in the greenhouse and then incubated overnight at 20°C and 100% relative humidity to promote sporulation of lesions, while systemic symptoms were evaluated after an additional 2 weeks in the greenhouse. There were 10 seeds planted per replicate and four replicates per line. The experiment was repeated once. Sporulation occurred on 54 and 64% of plants, and systemic symptoms on 53 and 82% of plants of P3-resistant line SC155 in two experiments, respectively. There were no local lesions or systemic symptoms on SC155 plants inoculated with several P3 isolates. Lines SC414-12E, QL3-India, 82BDM499, and 85EON495, which are resistant to P3, were also resistant to this isolate (i.e., no local lesions or systemic symptoms). Lines RTx2536, RTx430, CS3541, RTx7078, and SC170-6-17, which are susceptible to P3, were also susceptible to this isolate (54 to 100% incidence of systemic symptoms). An experiment (repeated once) that compared the reaction of this new pathotype on metalaxyl-treated and nontreated seed of a P3-resistant hybrid and a P3-susceptible hybrid, with reactions of metalaxyl-resistant P3 isolate and a metalaxyl-sensitive P3 isolate, showed that this pathotype, in addition to overcoming the genetic resistance, was also fungicide resistant. The pathogenicity of this new pathotype to other commercial P3-resistant hybrids is not yet known. There was no yield loss associated with this outbreak. However, the presence of a new pathotype, in combination with fungicide resistance, could lead to further outbreaks of SDM in the Upper Coast of Texas with the potential for yield loss. References: (1) J. Craig. Plant Dis. 71:356, 1987. (2) T. Isakeit et al. (Abstr.) Phytopathology 93:S39, 2003.

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Intercropping organic field peas with barley, oats and mustard improves weed control but has variable effects on grain yield and net returns

Canadian Journal of Plant Science ◽

10.1139/cjps-2021-0182 ◽

2021 ◽

Author(s):

Will Bailey-Elkin ◽

Michelle K. Carkner ◽

Martin Entz

Keyword(s):

Grain Yield ◽

Weed Control ◽

Yield Loss ◽

Weed Suppression ◽

Field Pea ◽

Separate Experiment ◽

Seeding Rate ◽

Weed Biomass ◽

Net Return ◽

Field Peas

Interest in intercropping semi-leafless field peas (Pisum sativum L.) is increasing as a means of weed control in organic production. We evaluated field pea (cv. CDC Amarillo) grown alone or intercropped with three seeding rates of either barley (Hordeum vulgare L.), mustard (Brassica juncea L.), or oats (Avena sativa L.). A full seeding rate of field pea was used in each instance, resulting in an additive intercropping design. Each crop combination was conducted in a separate experiment, three times over two years (2019 and 2020) in Carman, Manitoba. Measurements included crop and weed biomass production, grain yield and quality, and net return. Intercrops reduced weed biomass at maturity from 17 to 44% with barley and oats being more suppressive than mustard. Intercrops also reduced field pea yield from 6 to 26%, but increased field pea seed mass. Barley at the high seeding rate provided the most weed suppression per unit of field pea yield loss (2.62 kg of weed suppression per kg of field pea yield loss) compared with oat (1.29) and mustard (0.87). Barley and mustard intercrops decreased net return compared to monoculture field pea. Under low weed pressure (1150 kg ha-1 weed biomass at maturity) and earlier seeding, oat intercrops reduced net return. However, under weedy conditions (2649 kg ha-1) and later seeding, field pea-oat intercrops significantly increased net return. In conclusion, while all three intercrop mixtures reduced weed biomass, reductions in field pea yields were observed, and net return benefits were observed only in certain circumstances.

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Duration of Downy Mildew Control Achieved with Fungicides on Cucumber under Florida Field Conditions

Plant Disease ◽

10.1094/pdis-03-21-0507-re ◽

2021 ◽

Author(s):

Andy Shirley ◽

Gary E Vallad ◽

Nicholas Steven Dufault ◽

Richard Raid ◽

Lina Quesada-Ocampo

Keyword(s):

Downy Mildew ◽

Fungicide Resistance ◽

Yield Loss ◽

Continuous Production ◽

Field Conditions ◽

Pathogen Population ◽

Resistance Selection ◽

Progress Curve ◽

Field Activity ◽

Nearly Continuous

Cucurbit production in Florida is impacted by downy mildew on a yearly basis. Cucurbit downy mildew (CDM), caused by Pseudoperonospora cubensis, is one of the most devastating cucurbit diseases and can lead to complete yield loss. Nearly continuous production of cucurbits occurs temporally throughout Florida, which puts extensive pressure on the pathogen population to select for individuals that are resistant to current fungicides labeled for CDM. Loss of efficacy due to fungicide resistance developing is becoming a major concern for Florida cucurbit growers who rely on these products to manage CDM. This study was established to evaluate the field activity of eleven currently utilized fungicides by determining their duration of activity when applied at various intervals for the management of CDM in cucumber under Florida field conditions. By comparing levels of percent CDM control and area under the disease progress curve (AUDPC) values, the fungicide’s duration of field activity was established. Field activities were less than one week for dimethomorph and fluopicolide; one week for cymoxanil; one to two weeks for chlorothalonil and mancozeb; two weeks for ethaboxam; two to three weeks for propamocarb , cyazofamid, and ametoctradin + dimethomorph; and two to four weeks for oxathiapiprolin and fluazinam. Knowledge of duration of field activity can potentially improve the development of CDM management programs and slow resistance selection.

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