Tag Archives: disease severity

1499-1518 Nurholis, S.H. Hidayat, K.H. Mutaqin, S. Widodo and Widodo
Morphological, molecular, and pathogenic characterization of Colletotrichum gloeosporioides sensu stricto associated with imported citrus fruits
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Morphological, molecular, and pathogenic characterization of Colletotrichum gloeosporioides sensu stricto associated with imported citrus fruits

Nurholis¹, S.H. Hidayat¹, K.H. Mutaqin¹, S. Widodo² and Widodo¹*

¹IPB University, Faculty of Agriculture, Department of Plant Protection, Jl. Kamper Babakan Dramaga, Kabupaten Bogor, ID16680 Jawa Barat, Indonesia
²IPB University, Faculty of Agricultural Technology, Department of Agricultural Engineering and Biosystem, Jl. Kamper Babakan Dramaga, Kabupaten Bogor, ID16680 Jawa Barat, Indonesia
*Correspondence: widodo@apps.ipb.ac.id

Abstract:

Colletotrichum gloeosporioides is a fungal pathogen that causes anthracnose disease in citrus fruits. C. gloeosporioides has the potential to be carried by imported citrus fruits. The aim of this study was to detect, isolate, identify, and test the pathogenicity of C. gloeosporioides associated with imported citrus fruits. The detection method was carried out by freezing imported citrus fruits at -20 °C for 15 hours. C. gloeosporioides was identified morphologically and molecularly. The morphological identification method was done by observing mycelial colonies and conidia. The molecular identification method was done by the Polymerase Chain Reaction technique using 3 locus of ITS, GAPDH, and TUB2. The pathogenicity was tested by attaching 1 culture circle of C. gloeosporioides to the surface of the citrus fruit and injecting 100 µl of conidia suspension at a density of 105 conidia mL-1 into the inside of the citrus fruit. The main results showed that C. gloeosporioides was successfully detected at 4 days after incubation by the emergence of mycelia on the surface of citrus fruits. Morphological and molecular identification proved that the species of fungus was C. gloeosporioides sensu stricto which was a pathogenic fungus on imported and local citrus fruits with a disease incidence value of 100%, and a disease severity value of 97.78% and 98.89%, respectively.

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716–724 L. Feodorova-Fedotova, B. Bankina and V. Strazdina
Possibilities for the biological control of yellow rust (Puccinia striiformis f. sp. tritici) in winter wheat in Latvia in 2017–2018
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Possibilities for the biological control of yellow rust (Puccinia striiformis f. sp. tritici) in winter wheat in Latvia in 2017–2018

L. Feodorova-Fedotova¹²*, B. Bankina² and V. Strazdina³

¹Institute of Plant Protection Research, Latvia University of Life Sciences and Technology, Paula Lejina 2, LV–3001 Jelgava, Latvia
²Latvia University of Life Sciences and Technology, Faculty of Agriculture, Liela 2, LV–3001 Jelgava, Latvia
³Institute of Agricultural Resources and Economics, Stende Research Centre, “Dizzemes”, LV–3258 Dizstende, Talsu distr., Latvia
*Correspondence: liga.feodorova-fedotova@llu.llv

Abstract:

Yellow rust, caused by Puccinia striiformis f. sp. tritici, is a significant wheat disease worldwide. In Latvia, the distribution of yellow rust has increased recently and new aggressive races have been identified. The aim of this research was to investigate the possibilities for the biological control of yellow rust in winter wheat. A field trial was established in a biological field of winter wheat in Latvia in 2017 and 2018. Biological products that contained Bacillus spp., Pseudomonas aurantiaca, Brevibacillus spp., Acinetobacter spp., and chitosan were used for treatments, and one variant was left untreated. The efficacy of products was evaluated by the AUDPC (area under the disease progress curve) comparison. Differences in the severity of yellow rust between the trial years were observed. In 2018, the severity of yellow rust was lower than in 2017. In untreated plots, on flag leaf, the severity varied from 10.9% to 32.5% in 2017 and from 1.4% to 6.5% in 2018. In 2017, the severity of yellow rust reached its maximum on 05.07. at wheat growth stage (GS) 79, and in 2018 – on 20.06. GS 79. Both in 2017 and 2018, no significant differences (p > 0.05) were found in AUDPC values among the variants. After two years of investigations, the results were not convincing; therefore, further research is needed.

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735-742 I. Tupits and P. Sooväli
The occurrence and severity of rust diseases of winter rye in Estonian climatic conditions
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The occurrence and severity of rust diseases of winter rye in Estonian climatic conditions

I. Tupits¹⋅² and P. Sooväli¹⋅²

¹Jõgeva Plant Breeding Institute, 1 J. Aamisepa St., 48309 Jõgeva alevik, Estonia;e-mail: Ilme.Tupits@jpbi.ee; Pille.Soovali@jpbi.ee
²Institute of Agricultural and Environmental Sciences, Estonian University of LifeSciences, 1a Fr.R. Kreutzwaldi St., 51014 Tartu, Estonia

Abstract:

This paper presents a six-year study (2000–2005) of rusts on 11 winter rye varieties in Estonian conditions. Environmental factors may be related to occurrence of different pathogens causing rye diseases. The aim of the study was to analyse the influence of environmental factors on the occurrence of rust diseases on rye. Visual assessments of Puccinia recondita at inflorescence emergence (GS 50) and Puccinia graminis at milk ripening stage (GS 75) under natural infection conditions were carried out. As to average of the years, trial results demonstrated quite moderate infection level in the field conditions at the Jõgeva Plant Breeding Institute (PBI). The year’s climatic conditions had significant influence on the occurrence of stem rust. The impact of year to leaf rust was insignificant. Genotype had an insignificant effect on stem and leaf rust. Stem rust correlated highly with year and variety – R2 = 70.3%, p < 0.001. Neither year nor variety had any impact on the occurrence of leaf rust (R² = 40.6%).

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121–133 I. Brazauskiene and E. Petraitiene
Effects of fungicide application timing on the incidence and severity of Alternaria blight (Alternaria brassicae) and on the productivity of spring oilseed rape (Brassica napus L. ssp. oleifera annua Metzg.)
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Effects of fungicide application timing on the incidence and severity of Alternaria blight (Alternaria brassicae) and on the productivity of spring oilseed rape (Brassica napus L. ssp. oleifera annua Metzg.)

I. Brazauskiene and E. Petraitiene

Lithuanian Institute of Agriculture, Department of Plant Pathology and Protection, Instituto al. 1, Akademija, Dotnuva, LT-58344, Kedainiai distr., Lithuania;
e-mail: brazausk@lzi.lt, egle@lzi.lt

Abstract:

Three field experiments were carried out with the spring oilseed rape (Brassica napus L. ssp. oleifera annua Metzg.) cv. ‘Star’ to investigate the incidence, severity and harmfulness of Alternaria blight (Alternaria brassicae) and to test the possibility of reducing the disease pressure by fungicidal spray applications of 45% Sportak (a.i. prochloraz) 0.675 kg a.i. ha-1 and 25% Folicur (a.i. tebuconazole) 0.25 kg a.i. ha-1. The fungicides were applied at different times, i.e. after the first spots ofAlternaria blight had appeared on the lower, middle and upper leaves or on siliques and at the end of spring oilseed rape flowering. Alternaria blight was present in crops of the spring oilseed rape cv. ‘Star’ in all the experimental years. The disease severity varied in individual years and was heavily dependent on the weather conditions (amount of precipitation and temperature). Of all the experimental years, the most conductive conditions to the spread and development of Alternaria blight on spring rape siliques occurred in 1998, when disease spots covered 18.65% of the surface area of siliques in the untreated plots. The tested fungicides had little effect on the disease incidence, however, prochloraz and tebuconazole applied on all dates declined the disease severity. The highest efficacy was recorded when the fungicides were applied after the first symptoms of Alternaria blight had been spotted on siliques. Tebuconazole suppressed the disease severity more effectively than prochloraz.
In the year most favourable for Alternaria blight occurrence (1998), the seed yield in the untreated plots was by up to 0.07 t ha-1 lower, and the disease severity on siliques was as much as 3.2 times higher than in the fungicide-sprayed treatment. The highest average spring rape seed yield increase resulting from fungicidal spray applications during the period 1997–1999 amounted to 0.040 t ha-1. Fungicides declined the content of Alternaria blight diseased seeds per silique, increased 1,000-seed weight, however, no significant effect of fungicides was identified on the number of siliques per plant and the number of seeds per siliqua.

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