Time of sowing and fungicides affect blackleg (Leptosphaeria maculans) severity and yield in canola

2004 ◽  
Vol 44 (12) ◽  
pp. 1205 ◽  
Author(s):  
R. K. Khangura ◽  
M. J. Barbetti
Keyword(s):  
Foliar Application ◽  
Leptosphaeria Maculans ◽  
Growing Season ◽  
Yield Losses ◽  
Brassica Napus L ◽  
Seed Dressing ◽  
Maximum Protection ◽  
Disease Pressure ◽  
Seed Yields ◽  
First Time

Three different times of sowing in conjunction with various fungicide treatments were evaluated for the management of blackleg in canola (Brassica napus L.) variety Karoo. The trials were conducted at 4 different locations in Western Australia: East Chapman, Merredin, Wongan Hills and Mt Barker, representing a range of environmental conditions. The first time of sowing was at the break of the season followed by 2 subsequent sowings about 3 and 6 weeks later. Blackleg severity was significantly reduced by 14% when sowing was delayed until the end of June or early July, however, there were yield penalties due to the shortened growing season. Yield losses from blackleg were 16, 38 and 34% for mid-May, early to mid-June and end June to early July sown crops, respectively. All the fungicide treatments substantially reduced blackleg severity and increased yields at all the locations except for East Chapman (low rainfall site). The maximum protection fungicide treatment (Jockey seed dressing at 6.6 g a.i./kg seed + Impact in-furrow at 100 g a.i./ha + 3 foliar applications of flusilazole at 100 g a.i/ha) improved seed yield by 47, 56, 46 and 16% at Merredin, Wongan Hills and Mt Barker and East Chapman, respectively, compared with the nil treatment. Averaged over time of sowing and locations, the treatments of Jockey and Impact reduced disease severities by 20 and 25% and increased seed yields by 19 and 24%, respectively. There is potential for some other fungicide treatments, such as seed dressing with Jockey in combination with foliar application of either flusilazole or prochloraz, for the control of blackleg. These investigations suggest that damage from blackleg, in some areas during some seasons, could be minimised by sowing canola crops as early as possible before the onset of maturation of pseudothecia thus avoiding major ascospore showers at the seedling stage of maximum susceptibility. However, in case of a late break of season, fungicide protection may be essential to minimise losses from blackleg, particularly if sowing moderately susceptible cultivars under moderate to high disease pressure situations.

Yield losses in canola in response to blackleg disease

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.

scholarly journals Ethylenediurea (EDU) effects on Japanese larch: an one growing season experiment with simulated regenerating communities and a four growing season application to individual saplings

2020 ◽  
Author(s):  
Evgenios Agathokleous ◽  
Mitsutoshi Kitao ◽  
Xiaona Wang ◽  
Qiaozhi Mao ◽  
Hisanori Harayama ◽  
...  
Keyword(s):  
Ground Level ◽  
Growing Season ◽  
Japanese Larch ◽  
Larix Kaempferi ◽  
Ground Level Ozone ◽  
Growing Seasons ◽  
Inhibition Of Growth ◽  
Induced Stress ◽  
Maximum Protection ◽  
First Time

Abstract Japanese larch (Larix kaempferi (Lamb.) Carr.) and its hybrid are economically important coniferous trees widely grown in the Northern Hemisphere. Ground-level ozone (O3) concentrations have increased since the pre-industrial era, and research projects showed that Japanese larch is susceptible to elevated O3 exposures. Therefore, methodologies are needed to (1) protect Japanese larch against O3 damage and (2) conduct biomonitoring of O3 in Japanese larch forests and, thus, monitor O3 risks to Japanese larch. For the first time, this study evaluates whether the synthetic chemical ethylenediurea (EDU) can protect Japanese larch against O3 damage, in two independent experiments. In the first experiment, seedling communities, simulating natural regeneration, were treated with EDU (0, 100, 200, and 400 mg L−1) and exposed to either ambient or elevated O3 in a growing season. In the second experiment, individually-grown saplings were treated with EDU (0, 200 and 400 mg L−1) and exposed to ambient O3 in two growing seasons and to elevated O3 in the succeeding two growing seasons. The two experiments revealed that EDU concentrations of 200–400 mg L−1 could protect Japanese larch seedling communities and individual saplings against O3-induced inhibition of growth and productivity. However, EDU concentrations ≤ 200 mg L−1 did offer only partial protection when seedling communities were coping with higher level of O3-induced stress, and only 400 mg EDU L−1 fully protected communities under higher stress. Therefore, we conclude that among the concentrations tested the concentration offering maximum protection to Japanese larch plants under high competition and O3-induced stress is that of 400 mg EDU L−1. The results of this study can provide a valuable resource of information for applied forestry in an O3-polluted world.

scholarly journals Comparison on the Nutrient Plunder Capacity of Orychophragmus violaceus and Brassica napus L. Based on Electrophysiological Information

Horticulturae ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 206
Author(s):  
Cheng Zhang ◽  
Yue Su ◽  
Yanyou Wu ◽  
Haitao Li ◽  
Ying Zhou ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Orychophragmus Violaceus ◽  
Nutrient Metabolism ◽  
Brassica Napus L ◽  
Adaptive Mechanisms ◽  
Capacitive Reactance ◽  
Time Determination ◽  
Almost All ◽  
First Time

The nutrient metabolism, growth and development of plants are strongly affected by its nutrient plunder, and plants have different adaptive mechanisms to low-nutrient environments. The electrophysiological activities involve almost all life processes of plants. In this study, the active transport flow of nutrient (NAF) and nutrient plunder capacity (NPC) of plants were defined based on leaf intrinsic impedance (IZ), capacitive reactance (IXc), inductive reactance (IXL) and capacitance (IC) to evaluate the nutrient plunder capacity of plants for the first time. The results indicate that Orychophragmus violaceus had higher (p < 0.01) NPC and IC and lower (p < 0.01) IR, IXc, IXL and IZ as compared to Brassica napus L., which supports a superior ion affinity and that it could be better adapted to low-nutrient environments. UAF and NPC of plants exhibited good correlations with crude protein, crude ash and water content, and precisely revealed the plunder capacity and adaptive strategies of plants to nutrients. The present work highlights that O. violaceus had superior NPC and ion affinity compared with B. napus, and provided a novel, rapid, reliable method based on the plant’s electrophysiological information for real-time determination of the nutrient plunder capacity of plants.

Development of an agronomically superior blackleg resistant canola cultivar in Brassica napus L. using doubled haploidy

1995 ◽  
Vol 75 (2) ◽  
pp. 437-439 ◽  
Author(s):  
G. R. Stringam ◽  
V. K. Bansal ◽  
M. R. Thiagarajah ◽  
D. F. Degenhardt ◽  
J. P. Tewari
Keyword(s):  
Brassica Napus ◽  
Doubled Haploid ◽  
Leptosphaeria Maculans ◽  
Resistance Breeding ◽  
Breeding Method ◽  
Brassica Napus L ◽  
Breeding Lines ◽  
University Of Alberta ◽  
Blackleg Resistance ◽  
The University

The doubled haploid breeding method and greenhouse screening using cotyledon bio-assay were successfully applied to transfer blackleg resistance from the Australian cultivar Maluka (Brassicas napus), into susceptible advanced B. napus lines from the University of Alberta. This approach for blackleg resistance breeding was effective and efficient as several superior blackleg resistant breeding lines were identified within 4 yr from the initial cross. One of these lines (91–21864NA) was entered in the 1993 trials of the Western Canada Canola/Rapeseed Recommending Committee. Key words: Blackleg resistance, Leptosphaeria maculans, doubled haploid, Brassica napus

Chemical manipulation of Leptosphaeria maculans (blackleg disease) pseudothecial development and timing of ascospore discharge from canola (Brassica napus) residues

2003 ◽  
Vol 54 (9) ◽  
pp. 837 ◽  
Author(s):  
A. D. Wherrett ◽  
K. Sivasithamparam ◽  
M. J. Barbetti
Keyword(s):  
Developmental Stages ◽  
Severe Disease ◽  
Leptosphaeria Maculans ◽  
Potential Method ◽  
Chemical Treatments ◽  
Ascospore Discharge ◽  
Significant Difference ◽  
Significant Efficacy ◽  
Early Seedling ◽  
Disease Pressure

A study was carried out to establish key developmental stages of Leptosphaeria maculans on canola residues leading up to ascospore discharge and how these stages could be affected by chemicals. The residues were dipped in a range of chemicals, including fungicides, herbicides, and surfactants, to determine possible manipulative effects of the chemicals on the development of the fungus including ascospore discharge. Treated residues were placed in the field during the growing season. Ascospore discharge was found to be closely related to pseudothecial maturity and density. There was no significant difference between pseudothecial maturation on the crown component compared with the stem component. A high correlation between rainfall and pseudothecial density suggested that rainfall was a good complimentary indicator for timing of ascospore discharge. These results may provide the canola industry with a potential method of monitoring pseudothecial development for estimating disease hazards. This would allow manipulation of sowing times so as to minimise or avoid heavy ascospore showers coinciding with the early seedling phase. Twenty chemical treatments showed significant efficacy in decreasing ascospore numbers early in the season, most often by delaying the development of the pseudothecia on the residues. Two scenarios were formulated giving growers the potential to manipulate pseudothecial development and/or ascospore discharge. Firstly, a number of chemicals, such as fluquinconazole, technical grade flutriafol, and gluphosinate-ammonium, were able to delay pseudothecial development and subsequent ascospore discharge was decreased by 100%, 99%, and 96%, respectively. This scenario gives growers the potential to minimise synchronisation of ascospore discharge with early crop establishment. Secondly, a situation where pseudothecial development is not delayed, but number of ascospores discharged is reduced (e.g. ziram by 45%) would only be effective if the reduction resulted in a less severe disease epidemic. There is significant potential for development of commercial chemical treatments of residues to reduce disease pressure on seedlings.

scholarly journals Методы оценки продуктивности представителей рода эхинацея (Echinacea Moench) прегенеративного периода онтогенеза

2013 ◽  
pp. 24-30
Author(s):  
С. В. Поспелов
Keyword(s):  
Regression Models ◽  
Input Data ◽  
Growing Season ◽  
Echinacea Purpurea ◽  
System Productivity ◽  
Aerial Parts ◽  
Purple Coneflower ◽  
Echinacea Pallida ◽  
First Time

За багаторічними дослідженнями ехінацеї пурпурової (Echinacea purpurea (L.) Moench,) сорту Зірка Миколи Вавилова та ехінацеї блідої (Echinacea pallida (Nutt.) Nutt.) сорту Красуня Прерій вперше розроблені й запатентовані методи визначення продуктивності рослин прегенеративного періоду онтогенезу. Методики засновані на регресійних моделях із високими коефіцієнтами детермінації, на підставі яких можна без пошкодження рослин провести оцінку продуктивності надземної частини та кореневої системи протягом веґетаційного періоду. Вихідними даними для розрахунків слугують показники довжини і ширини листковоїпластинки, їх кількість, а також сума температур вище 5 0С і кількість діб від сівби. On the basis of long-term researches of Purple Coneflower (Echinacea purpurea (L.) Moench) variety «Zirka Mykoly Vavylova» and Pale Coneflower (Echinacea pallida (Nutt.) variety «Krasunja Preriy» for the first time ever there were developed and patented the methods for determining the efficiency of plants in pregenesic period of ontogeny. The foundation of methodology was made on the studies of regression models with high coefficients of determination which allow to make the estimation of aerial parts and root system productivity for the whole growing season without damaging the plants. The input data for the calculation are the indicators of the length and width of the leaf blade, the amount and the sum of temperatures above + 5 ºC and the number of days from sowing.

When is fall feeding by flea beetles (Phyllotreta spp., Coleoptera: Chrysomelidae) on canola (Brassica napus L.) a problem?

2012 ◽  
Vol 92 (1) ◽  
pp. 97-107
Author(s):  
Juliana J. Soroka ◽  
Larry F. Grenkow
Keyword(s):  
Brassica Napus ◽  
Field Experiments ◽  
Flea Beetle ◽  
Brassica Napus L ◽  
Late Season ◽  
The Third ◽  
Flea Beetles ◽  
Seeding Date ◽  
Seed Yields

Soroka, J. J. and L. F. Grenkow. 2012. When is fall feeding by flea beetles ( Phyllotreta spp., Coleoptera: Chrysomelidae) on canola ( Brassica napus L.) a problem? Can. J. Plant Sci. 92: 97–107. Two cultivars of Brassica napus canola were seeded in mid-May and early June in three field experiments in each of 3 yr near Saskatoon, Saskatchewan, to determine the effects of late-season flea beetle feeding on seed yields. In the first experiment, canola was sprayed with insecticide late in the summer to eliminate naturally-infesting flea beetles. In the second, 1×1×1.5 m screen cages were placed over early- and late-seeded canola at flowering and infested with flea beetles as canola matured. In the third investigation, sleeve cages were placed over individual plants and infested with 100 flea beetles. Flea beetles had no detrimental effects on early-seeded canola in any experiment, but did affect seed yields of late-seeded plots in some trials. Over two cultivars in 1 year, late-seeded plants in cube cages infested with about 350 flea beetles per plant when lower pods were turning from translucent to green in colour reduced yield by 241 kg ha−1 over control yields. Seed weights in these late-seeded plots were decreased from 2.68 g per 1000 seeds in uninfested cages to 2.44 g per 1000 seeds in infested cages. Populations of 100 flea beetles per plant in sleeve cages had no effect on harvest parameters in any seeding date or year.

scholarly journals Impact of Foliar Application with Salicylic Acid on Biochemical Characters of Canola Plants under Cold Stress Condition

2016 ◽  
Vol 8 (1) ◽  
pp. 98-105 ◽  
Author(s):  
Hamed KESHAVARZ ◽  
Seyed Ali Mohammad MODARRES SANAVY ◽  
Ramin SADEGH GHOL MOGHADAM
Keyword(s):  
Salicylic Acid ◽  
Brassica Napus ◽  
Acid Treatment ◽  
Stress Condition ◽  
Foliar Application ◽  
Total Chlorophyll ◽  
Salicylic Acid Treatment ◽  
Biochemical Traits ◽  
Brassica Napus L ◽  
Salicylic Acid Concentration

In this study the effect of foliar application of salicylic acid on the chlorophyll content, antioxidant enzymes activity, and the content of solute protein and proline were investigated in two canola varieties (Brassica napus L., cv ‘RGS’ and ‘Licord’) leaves during 0, 24, and 48 hours after salicylic acid treatment. The results showed that the content of total chlorophyll was decreased in ‘RGS’ cultivar during the experiment and this process was related with increasing of salicylic acid concentration. The activity of superoxide dismutase, peroxidase, and also lipid peroxidation were increased significantly after 48 hours compared with the first day. The results of catalase activity showed that, this trait was decreased 24 hours after salicylic acid treatment and this decrease was related with salicylic concentration. The content of protein in both cultivars slightly changed and plants treated with salicylic acid had more protein content, by contrast proline was greatly affected by salicylic acid treatment and its content was the highest 24 hours after treatment. According to the present findings the application of salicylic acid has useful effects on the biochemical traits of Brassica napus cultivars. Therefore it may be effective for the improvement of plant growth in cold regions.

scholarly journals  Effect of 2,4-D as a novel inducer of embryogenesis in microspores of Brassica napus L.

2011 ◽  
Vol 47 (No. 3) ◽  
pp. 114-122 ◽  
Author(s):  
S.H. Ardebili ◽  
M.E. Shariatpanahi ◽  
R. Amiri ◽  
M. Emamifar ◽  
M. Oroojloo ◽  
...  
Keyword(s):  
Brassica Napus ◽  
Heat Shock ◽  
Microspore Embryogenesis ◽  
Control Treatment ◽  
Dichlorophenoxyacetic Acid ◽  
Brassica Napus L ◽  
High Concentrations ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Short Time ◽  
First Time

The effect of 2,4-dichlorophenoxyacetic acid (2,4-D) applied at high concentrations for a short time was investigated as a novel stress for induction of microspore embryogenesis for the first time. Brassica napus L. cvs. Topas and Hyola 420 were used as model plants for testing this hypothesis. Microspores were subjected to 2,4-D at 4 concentrations (15, 25, 35 and 45 mg/l) for 15&ndash;45 min while the classical heat shock was used as the control treatment. Among 2,4-D treatments in Topas, the highest yield of torpedo-stage embryos was achieved at 15 mg/l 2,4-D for 30 min while more normal plantlets were produced when 2,4-D (25 mg/l for 30&nbsp;min) was applied to the microspores. In Hyola 420 the results showed a lower number of embryos and normal plantlets at all concentrations of 2,4-D. Although Hyola 420 was almost equally embryogenic as Topas after heat shock treatment, large differences between genotypes (concerning embryogenic response) occurred after 2,4-D treatment. However, the mean number of embryos and regenerants was higher in heat shock as compared to 2,4-D induced stress (one magnitude of order). According to the results obtained, 2,4-D can be introduced as a new stress for induction of embryogenesis in microspores similarly like in zygotic and somatic cells. This novel stress is very important for plant species whose microspores are extremely sensitive to classical stresses.

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