scholarly journals Factors Affecting Infection and Disease Development on Olive Leaves Inoculated with Fusicladium oleagineum

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1139-1146 ◽  
Author(s):  
José R. Viruega ◽  
Luis F. Roca ◽  
Juan Moral ◽  
Antonio Trapero
Keyword(s):  
Incubation Period ◽  
Disease Severity ◽  
Disease Incidence ◽  
Leaf Age ◽  
Growth Chamber ◽  
Factors Affecting ◽  
Potted Plants ◽  
Inoculum Dose ◽  
Detached Leaves ◽  
Forecasting System

Infection and development of olive scab disease, caused by Fusicladium oleagineum, were evaluated on detached leaves and potted plants of the susceptible cultivar Picual in growth chambers and a shadehouse. An inoculum dose of 1 × 105 conidia per ml was selected from a range of densities tested, and it was used for all experiments. Infection occurred from 5 to 25°C, and disease severity was the greatest at ~20°C for wetness durations of 12 to 24 h and at ~15°C for longer durations. Based on a generalized form of the Analytis Beta model, the optimum temperature and minimum wetness duration for infection were 15.5°C and 11.9 h. Dry periods ≤78 h immediately after inoculation did not reduce disease incidence but did reduce disease severity. Disease severity was negatively correlated with leaf age. Disease incubation period was positively correlated with leaf age, with a minimum incubation period of 28 days in the youngest leaves. Inoculated plants that were incubated in a growth chamber or in a shadehouse had the same level of infection, but disease severity was lower in plants incubated in the growth chamber because many infections remained latent for 6 months after inoculation. The data in this study will be useful for the development of a forecasting system for olive scab epidemics.

scholarly journals Continuous Lighting Reduces Conidial Production and Germinability in the Rose Powdery Mildew Pathosystem

Plant Disease ◽  
2010 ◽  
Vol 94 (3) ◽  
pp. 339-344 ◽  
Author(s):  
A. Suthaparan ◽  
Arne Stensvand ◽  
S. Torre ◽  
Maria L. Herrero ◽  
R. I. Pettersen ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Disease Severity ◽  
Interspecific Hybrid ◽  
Day Length ◽  
Artificial Light ◽  
Potted Plants ◽  
Severity Of Disease ◽  
Detached Leaves ◽  
Growth Chambers ◽  
The Rose

The effect of day length on production and germinability of conidia and severity of disease caused by Podosphaera pannosa, the causal agent of rose powdery mildew, was studied. Whole potted plants or detached leaves of Rosa interspecific hybrid ‘Mistral’ were inoculated with P. pannosa and exposed to 0, 12, 18, 20, 22, or 24 h of artificial light per day in growth chambers equipped with mercury lamps. Increasing duration of illumination from 18 to 20 to 24 h per day reduced production of conidia by 22 to 62%. Exposure to 24 h of illumination per day also strongly reduced disease severity compared with 18 h. Our results suggest that increasing day lengths from 18 h per day to 20 to 24 h may suppress the disease significantly and, thereby, reduce the need for fungicide applications against powdery mildew.

scholarly journals Phenotyping Sunflower Genetic Resources for Sclerotinia Head Rot Response: Assessing Variability for Disease Resistance Breeding

Plant Disease ◽  
2017 ◽  
Vol 101 (11) ◽  
pp. 1941-1948 ◽  
Author(s):  
C. V. Filippi ◽  
J. E. Zubrzycki ◽  
J. A. Di Rienzo ◽  
F. Quiroz ◽  
C. M. Fusari ◽  
...  
Keyword(s):  
Incubation Period ◽  
Disease Severity ◽  
Phenotypic Variability ◽  
Disease Incidence ◽  
Block Design ◽  
Germplasm Collection ◽  
Phenotypic Characterization ◽  
Mixed Effect ◽  
Heritability Estimates ◽  
Head Rot

Sclerotinia head rot (SHR) is one of the most serious constraints to sunflower (Helianthus annuus L. var. macrocarpus) production worldwide. Here, we evaluated the response to SHR in a sunflower inbred panel from a large INTA germplasm collection, consisting of 137 inbred lines (ILs). Field trials were performed over five consecutive seasons using a twice-replicated randomized complete-block design. Disease incidence, disease severity, incubation period, and area under disease progress curve for disease incidence and severity were determined after controlled inoculation with the pathogen. Statistical analysis using mixed-effect models detected significant differences among ILs for all variables (P < 0.001). In addition, principal component analysis (PCA) and distance-based methods were used to classify the ILs according to their response to SHR, with ILs ALB2/5261 and 5383 emerging as the most resistant. Broad-sense heritability estimates ranged from 20.64% for disease severity to 10.58% for incubation period. The ample phenotypic variability of our collection, along with the moderate heritability estimates, highlight the importance of molecular breeding approaches to gain new insights into the genetic basis of sunflower resistance to SHR. The exhaustive phenotypic characterization presented here provides a reliable set of variables to comprehensively evaluate the disease and identifies two new sources of resistance to SHR.

scholarly journals Susceptibility of Boxwood Accessions from the National Boxwood Collection to Boxwood Blight and Potential for Differences between Calonectria pseudonaviculata and C. henricotiae

HortScience ◽  
2017 ◽  
Vol 52 (6) ◽  
pp. 873-879 ◽  
Author(s):  
James A. LaMondia ◽  
Nina Shishkoff
Keyword(s):  
Disease Severity ◽  
Size Effects ◽  
Plant Size ◽  
The Other ◽  
Potted Plants ◽  
Detached Leaf ◽  
Detached Leaves ◽  
The Individual ◽  
The U.S

Forty Buxus accessions from the U.S. National Arboretum National Boxwood Collection were evaluated as potted plants and detached leaves for susceptibility to Calonectria pseudonaviculata (Crous et al.) L. Lombard et al., and nine boxwood cultivars were evaluated against both species of Calonectria causing boxwood blight, C. pseudonaviculata and C. henricotiae. Accessions of B. harlandii Hance, B. sinica (Rehder and E.H.Wilson) M.Cheng, and B. microphylla Siebold and Zucc. had less disease than B. microphylla ×sempervirens, and all had fewer lesions per plant than the 20 B. sempervirens L. accessions evaluated. Variation within species was observed. Of the individual accessions, B. sinica var. aemulans (accession 60705*H), B. sempervirens (36365*J), and B. harlandii (18834*H) were least susceptible, with <10 lesions per plant. B. sempervirens ‘Scupi’ (9548*H), B. microphylla ‘Compacta’ (4899*CH), B. sempervirens ‘Arborescens’ (57953*H), B. sinica var. insularis ‘Pincushion’ (51898*H), and B. microphylla var. japonica ‘Jim Stauffer’ (72213*H) each had <20 lesions. These rankings differ from previous studies that used detached leaf and unrooted cutting assays. Normalizing to account for plant size effects on inoculation and disease increased variability for individual accession rankings but did not result in significant differences in the most and least susceptible accessions or species ranking. Nine boxwood cultivars evaluated against both pathogen species exhibited a range of susceptibility against four pooled isolates each of C. pseudonaviculata and C. henricotiae. Although small differences in disease severity were observed on boxwood inoculated with the two pathogens, there was no interaction of cultivar and pathogen species, suggesting that a cultivar rated resistant to one species was resistant to the other. These results may aid boxwood breeders to develop resistance to boxwood blight.

scholarly journals Resistensi Beberapa Varietas Bawang Merah Terhadap Colletotrichum Gloeosporioides

2018 ◽  
Vol 20 (2) ◽  
pp. 40
Author(s):  
Hekmawati Hekmawati ◽  
Susilo Hambeg Poromarto ◽  
Salim Widodo
Keyword(s):  
Incubation Period ◽  
Disease Severity ◽  
Colletotrichum Gloeosporioides ◽  
Disease Incidence ◽  
Dry Weight ◽  
Environmental Damage ◽  
Resistance Level ◽  
Randomized Design ◽  
Resistant Varieties ◽  
Completely Randomized Design

<p>Shallot is an important vegetable because it is needed for seasoning and beneficial for health. One of the problems in shallot cultivation is the decrease in productivity due to <em>Colletotrichum gloeosporioides</em> attack that caused anthracnose disease. The use of resistant varieties is a solution to control <em>C. gloeosporioides</em> which is safe and doesn't cause environmental damage. Shallot consists of many varieties, but their resistance level remains unknown. The research aimed to test the resistance of some varieties of shallots to <em>C. gloeosporioides</em>. Shallots varieties tested are Tajuk, Bauji, Bima Curut, Bima Rajat, Bali Lancur and Bali Karet. The research used a one-factor completely randomized design with 12 treatments and 5 replications. The results of the research showed that Tajuk, Bima Curut, Bali Lancur and Bali Karet varieties were highly susceptible due to disease severity of more than 71%, have a faster incubation period of anthracnose, high disease incidence and a significant decrease in tuber. Bauji and Bima Rajat varieties are classified as susceptible varieties due to disease severity of 64% but have a longer incubation period of anthracnose, higher number of tubers, higher fresh and dry weight of tubers and lower reduction in the number and weight of tubers.</p>

scholarly journals Sweet Orange Fruit Age and Inoculum Concentration Affect the Expression of Citrus Black Spot Symptoms

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 913-921 ◽  
Author(s):  
Guilherme F. Frare ◽  
Geraldo J. Silva-Junior ◽  
Fabrício E. Lanza ◽  
Renato B. Bassanezi ◽  
Thiago G. Ramires ◽  
...  
Keyword(s):  
Incubation Period ◽  
Sweet Orange ◽  
Disease Incidence ◽  
Black Spot ◽  
Conidial Germination ◽  
Inoculum Concentration ◽  
Factors Affecting ◽  
Citrus Black Spot ◽  
Incubation Periods ◽  
Orange Fruit

Citrus black spot (CBS), caused by Phyllosticta citricarpa, affects different citrus species worldwide. CBS is mainly expressed as false melanose and hard spot symptoms. There is no consensus in the literature about the period when fruit are susceptible to P. citricarpa infection and the length of the CBS incubation period. Therefore, this study aimed to assess the influence of sweet orange variety, fruit age, and inoculum concentration on the incubation period and the expression of different CBS symptoms. Attached fruit of Hamlin, Pera, and Valencia sweet orange at 1.5, 3.0, 5.0, and 7.0 cm diameter were inoculated with suspensions containing 103 and 105 conidia/ml of P. citricarpa. The percent conidial germination was quantified using scanning electron microscopy. The CBS symptoms on fruit were assessed monthly. The four diameters did not significantly affect conidial germination on the inoculated fruit, although CBS incidences were lower when larger fruit were inoculated. Hard spot symptoms on sweet orange fruit did not develop from the false melanose symptoms and vice versa. The incubation periods for false melanose were shorter than those observed for hard spot. False melanose began to appear 44 days after inoculation, but hard spot only formed at 113 days or later. Incubation periods were shorter and incidences of false melanose were higher following inoculation with higher inoculum concentration and smaller fruit diameter. The incubation period of hard spot varied among varieties and fruit diameters. However, there was no relationship between hard spot incidence and variety. This study provides a better understanding of the factors affecting the variation in the CBS incubation period and disease incidence on fruit.

STUDIES ON THE SEEDLING DISEASE OF BARLEY CAUSED BY HELMINTHOSPORIUM SATIVUM P.K. & B.

1956 ◽  
Vol 34 (4) ◽  
pp. 653-673 ◽  
Author(s):  
R. A. Ludwig ◽  
R. V. Clark ◽  
J. B. Julien ◽  
D. B. Robinson
Keyword(s):  
Disease Incidence ◽  
Infested Soil ◽  
Disease Development ◽  
Toxic Activity ◽  
Factors Affecting ◽  
Seedling Disease ◽  
Nutrient Salt ◽  
Helminthosporium Sativum ◽  
Treatment Comparisons

A standard sand – cornmeal – nutrient salt medium, for use in the production of artificial inoculum of Helminthosporium sativum, is described. This inoculum induces uniform plant disease development when thoroughly incorporated with the planting soil. The results presented clearly demonstrate the necessity of using a series of infestation levels in studies of factors affecting disease development in artificially infested soil. It is shown that considerable reliance can be placed on treatment comparisons within an experiment but that comparisons between experiments are much less accurate. The role of a toxin (or toxins) in disease development in barley seedlings has been demonstrated. The toxic activity was found to be distinct from that frequently encountered on addition of organic matter to soil. Results obtained suggest that toxin adsorption by the soil may play an important role in reducing disease incidence and severity.

scholarly journals Effect of Compost Amendments on Disease Severity and Yield of Tomato in Conventional and Organic Production Systems

Plant Disease ◽  
2002 ◽  
Vol 86 (2) ◽  
pp. 156-161 ◽  
Author(s):  
P. A. Abbasi ◽  
J. Al-Dahmani ◽  
F. Sahin ◽  
H. A. J. Hoitink ◽  
S. A. Miller
Keyword(s):  
Disease Severity ◽  
Production Systems ◽  
Disease Incidence ◽  
Organic Production ◽  
Fruit Rot ◽  
High Rate ◽  
Bacterial Spot ◽  
Marketable Yield ◽  
Tomato Production ◽  
Compost Amendments

Field trials were conducted over 2 years to assess the effects of compost amendments on disease development in organic and conventional processing tomato (Lycopersicon esculentum L.) production systems. The incidence of anthracnose fruit rot was reduced in organic tomato plots amended with a high rate of composted cannery wastes compared with the incidence in nonamended control plots in 1998 when disease incidence was high. Marketable yield was increased by 33% in compost-amended organic plots. Plots amended with a high compost rate had more ripe fruit than the nonamended control. The incidence of anthracnose and of total disease on fruit was less on the cultivar OH 8245 than on Peto 696. Total fruit yield of OH 8245 but not Peto 696 in organic plots was increased by amendment with composted cannery wastes. In conventional tomato production, composted yard wastes increased disease severity on foliage both years but reduced bacterial spot incidence on fruit in 1997, when disease pressure was high. The incidence of anthracnose was not affected by composted yard wastes. Marketable and total fruit yields of Peto 696 were not increased in compost-amended conventional plots. The plant activator Actigard reduced foliar disease severity and the incidence of bacterial spot and anthracnose on fruit, while increasing yield of marketable fruit.

scholarly journals Effect of irrigation frequency and fungicide spray on yield and disease infection of onion

1970 ◽  
Vol 34 (3) ◽  
pp. 417-424
Author(s):  
SK Biswas ◽  
MA Razzaque Akanda ◽  
M Rafi Uddin ◽  
PK Sarker
Keyword(s):  
Disease Severity ◽  
Water Use ◽  
Agricultural Research ◽  
Disease Incidence ◽  
Research Station ◽  
Irrigation Frequency ◽  
Yield Attributes ◽  
Irrigation Water Use ◽  
Use Efficiency ◽  
Bulb Yield

A two-year field experiment was conducted at Regional Agricultural Research Station, Jessore during the rabi seasons of 2002-2003 and 2003-2004 to find out the level of disease incidence under different levels of irrigation and fungicide spray on the bulb yield of onion. Four irrigation levels: no irrigation (I1), irrigation at 10 days interval (I2), 20 days interval (I3), and 30 days interval (14) with 4 spray schedules: no spray (F1), one spray at 40 days after transplanting (DAT) (F2), two sprays each at 40 and 55 DAT (F3) and three sprays each at 40, 55, and 70 DAT (F4) were used. Yield and yield attributes varied significantly (p = 0.05) between sprayed and unsprayed, and irrigated and non-irrigated treatments, respectively. Higher yields were obtained with the higher frequencies of irrigation and spray. Application of fungicide reduced the disease severity significantly, while irrigation had no significant effect on disease infection. But there was a decreasing trend of the disease severity with increasing irrigation frequency. The highest bulb yield of onion (12.45 t/ha) was obtained with a total water use of 245 mm in six applications including an effective rainfall of 16 mm and three sprays. The disease severity between sprayed and unsprayed plots ranged from 1.33 to 3.16 for I1, 1.08 to 2.33 for I2 1.16 to 2.83 for I3, and 1.16 to 3.00 for I4, respectively. Key Words: Onion, disease incidence, irrigation, water use efficiency. DOI: 10.3329/bjar.v34i3.3967 Bangladesh J. Agril. Res. 34(3) : 417-424, September 2009

scholarly journals Cotton resistance to ramulose and variability of Colletotrichum gossypii f. sp. cephalosporioides

2006 ◽  
Vol 32 (1) ◽  
pp. 9-15 ◽  
Author(s):  
Jefferson Fernandes do Nascimento ◽  
Laércio Zambolim ◽  
Francisco Xavier Ribeiro do Vale ◽  
Paulo Geraldo Berger ◽  
Paulo Roberto Cecon
Keyword(s):  
Disease Severity ◽  
Disease Incidence ◽  
Disease Index ◽  
Mato Grosso ◽  
Progress Curve ◽  
Commercial Cultivars ◽  
Resistant Group ◽  
The Relationship ◽  
Highly Virulent ◽  
Susceptible Group

Four cultivars and 21 lines of cotton were evaluated for resistance to ramulose (Colletotrichum gossypii f. sp. cephalosporioides) in a field where the disease is endemic. The seeds of each genotype were planted in 5 x 5 m plots with three replications. The lines CNPA 94-101 and 'CNPA Precoce 2'were used as standard susceptible and resistant references, respectively. The disease incidence (DI) was calculated from the proportion of diseased plants in the plot. The disease index (DIn) was calculated from the disease severity using a 1 to 9 scale, and was evaluated at weekly intervals starting 107 days after emergence. The data collected was used to calculate the area under disease progress curve (AUDPC). In general, the DIn increased linearly with time and varied from 20.0 to 57.1 and AUDPC from 567 to 1627 among the genotypes which could be clustered in to two distinct groups. The susceptible group contained two cultivars and nine lines and the resistant group contained one cultivar and 12 lines. The relationship between disease index and evaluation times was linear for the 25 genotypes tested. The line CNPA 94-101, used as susceptible standard, was the most susceptible with an average DI = 83.4, DIn = 57.1 and AUDPC = 1627.7. The line CNPA 96-08 with DI = 37.8, DIn = 20.0 and AUDPC = 567.7 was the most resistant one. Among the commercial cultivars 'IAC 22' was the most susceptible and 'CNPA Precoce 2', used as resistant standard was the most resistant. The variability in virulence of the pathogen was studied by spray inoculating nine genotypes with conidial suspensions (10(5)/mL) of either of the 10 isolates. The disease severity was evaluated 30 days later using a scale of 1 to 5. The virulence of the isolate was expressed by DIn. All the isolates were highly virulent but their virulence avaried for several genotypes and could be clustered in two distinct groups of less and more virulent isolates. The isolate MTRM 14 from Mato Grosso was the least virulent while Minas Gerais was the most virulent, with DIn of 6.36 and 46.47, respectively. In this experiment the line HR 102 and the cultivar 'Antares' were the most resistant ones with DIns of 18.32 and 19.14, respectively.

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