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Plant Pathology Journal

Peduncle blight, hitherto an unknown disease, was found to
be a major limiting factor to the cultivation of tuberose, as the disease incidence
was noticed up to 42.60% in pockets of Madurai district. Though, Lasiodiplodia
theobromae is an ubiquitous pathogen, its occurrence on tuberose is a new
record. The fungus induced confounding symptoms which included blossom blight,
peduncle blight and leaf blight at tips as well. The causal agent of the disease
was identified as Lasiodiplodia theobromae. The efficacy of fungicides
and biocontrol agents effective in in vitro was evaluated in pot culture
experiment to manage peduncle blight of tuberose. Foliar application of carbendazim
0.1% at 60, 90 and 110 Days After Planting (DAP) was found to be highly effective
in reducing the disease incidence up to 95.50%. Among the bioconrol agents,
bulb treatment at 10 g kg-1 followed by three foliar sprays at 0.5%
on 60, 90 and 110 DAP using the combination of Tv1, Pf1
and Bs10 was equally effective as that of Pf1 and Bs10
with 65.68 and 64.45% disease reduction, respectively. 2014/08/30 - 16:20

The eggplant (Solanum melongena) is one of the most widely grown vegetable crops all over the world, including the Indian sub-continent. This crop is prone to massive attacks by several species of fungi and bacteria that cause wilt, soft rot and root rot because of the increasing restriction in the use of chemical fungicides due to concern for the environment and human health, microbial inoculants have been experimented extensively during the last decade to control wilt and other plant diseases Bacteria have been explored as biocontrol agents for plant and also as plant growth promoters and inducers of disease resistance Apart from improving plant health, they also meet the increasing demand for low-input agriculture. The purpose of this study is to describe some important disease of brinjal and their management. 2014/08/30 - 16:20

Nanotechnology is one of the most fascinating and rapidly
advancing sciences and possess potential to revolutionize many disciplines of
science, technology, medicine and agriculture. Conversion of macromaterials
in to nano size particles (1-100 nm) gives birth to new characteristics and
the material behaves differently. Nanoparticles can be produced by different
methods, chemical and biological, the former is commercially used. Nanomaterials
can be potentially used in the crop protection, especially in the plant disease
management. Nanoparticles may act upon pathogens in a way similar to chemical
pesticides or the nanomaterials can be used as carrier of active ingredients
of pesticides, host defence inducing chemicals, etc. to the target pathogens.
Because of ultra small size, nanoparticles may hit/target virus particles and
may open a new field of virus control in plants. The disease diagnosis, pathogen
detection and residual analysis may become much more precise and quick with
the use of nanosensors. The present paper critically analyzes the relevance,
scope and application of nanotechnology in plant disease management in future
crop production. 2014/08/30 - 16:20

Tobacco black shank caused by Phytophthora nicotianae is one of the most destructive diseases suffered by tobacco in China. Streptomycin, calcium oxide and synthetic fertilizer are three important non-target chemicals used frequently during tobacco growing period. This study has evaluated the activities of the non-target chemicals streptomycin, calcium oxide and synthetic fertilizer on the mycelial growth, sporulation, zoospore formation and germination of cystospores of P. nicotianae. Metabolic fingerprints of P. nicotianae under pressures of those three chemicals are also compared with control treatments. Streptomycin inhibited mycelial growth, sporangia production, zoospore formation and cystospore germination more effectively than the other chemicals tested. Calcium oxide inhibited sporangia production, zoospore formation and cystospore germination at much higher concentration. Mycelial growth of P. nicotianae was not affected by this chemical. Synthetic fertilizer had negative or no effect on sporangia production and no effect on mycelial growth. Zoospore formation and cystospore germination was inhibited at high concentrations of this chemical. Metabolic fingerprint of P. nicotianae was not or poorly affected by calcium oxide and synthetic fertilizer. Streptomycin significantly changed the fingerprint of the pathogen, substrate of y-aminobutyric acid, fumaric acid, L-alaninamide, L-alanyl-glycine, L-proline, L-pyroglutamic acid and putrescine cannot be utilized by P. nicotianae. So it is no use to add calcium oxide to soil for black shank management in the field, while is useful for streptomycin. Synthetic fertilizer in some case may enhance the development of the disease. These new findings provide important information for black shank management in the future. 2014/08/10 - 20:15

Rice (Oryza sativa L.) is one of the major food crops
of the world. Due to lack of awareness, the farmers do not distinguish the seed
from grain and hence the quality of farmers saved seed remains below standard.
This seed carries microflora which play an important role in reducing the seed
viability. Among seed microflora, fungal load on the seed is very important.
In this study, seed samples of different varieties of paddy were collected from
farmers in different villages of Haryana from 2002 to 2012. The seed was subjected
to seed health test by blotter technique and observed under stereo-binocular
microscope to assess its fungal load. The per cent germination and vigour index
were also evaluated by paper towel method. A total of 30 fungi belonging to
different groups were recorded from the samples of farmers’
saved seed. Alternaria padwickii (28.52%), Curvularia lunata (22.67%),
Alternaria alternata (10.51%), Rhizopus stolonifer (8.96%), Aspergillus
flavus (8.26%) and Fusarium moniliforme (7.15%) were recorded as
major fungi associated with the seed. However, in breeder seed of different
paddy varieties grown at this station, only 22 fungal species belonging to different
groups were recorded. Out of which Alternaria padwickii (10.62%),
Curvularia lunata (7.35%), Alternaria alternata (6.54%), Aspergillus
flavus (6.07%) and Rhizopus stolonifer (5.21%) were recorded as the
major fungi associated with this seed. Average per cent germination and vigour
of farmers’ saved seed of different
paddy varieties was significantly lower than the breeder seed of different varieties
of paddy grown at this station. 2014/08/10 - 20:15

An experiment was conducted during 2006-2009 to study whether modified atmosphere with varying carbon dioxide concentration can protect seed from fungal infestation. Lower CO2 concentration upto 40% was ineffective in the control of seed mycoflora, however high concentrations of carbon dioxide reduced fungal incidence but none of the carbon dioxide concentrations tested, completely controlled fungal infestation in paddy seed or rice grain. CO2 at 60-80% concentrations (v/v) reduced the incidence of storage fungi viz., Curvularia lunata, Cladosporium sp., Rhizopus stolonifer and Alternaria alternata on stored paddy seed. But 80% CO2 was required to control Aspergillus flavus, an aflatoxin producing fungi. Modified atmosphere with oxygen at 5% concentration resulted in higher incidence of storage fungi (52.0%) as compared to 48.0% in basmati rice exposed to modified atmosphere with 2% O2 concentrations and with CO2 concentrations varying from 0-20%. 2014/08/10 - 20:15

Water fungi and fungus-like organisms as a biological factor of ecological water systems have significant influence on the environment and its modification. Fresh water samples were collected from region of Ganga River in Varanasi district, Uttar Pradesh, India. Three sampling sites which are known as ghats (stairways to the bank) Assi ghat, Rajendra ghat, Harishchandra ghat) were selected for sample collection. The water samples were examined for fungi by plating method culturing Potato dextrose agar medium. The isolated fungal strains were identified by lactophenol cotton blue staining. Results were found that a total of 23 micoflora were found to be dominant at three place of Ganga River in Varanasi District. In all three places maximum number of fungi was recorded in Assi ghat followed by Harishchandra ghat then Rajendra ghat. Aspergillus flavus and Aspergillus niger showed highest 36.75 and 29.50% frequency at Harishchandra ghat and Rajendra ghat. White sterile mycelium and Trichothecium roseum showed lowest 0.23 and 0.45% frequency in Assi ghat. 2014/08/10 - 20:15

The effect of application β-Aminobutyric Acid (BABA)
on Crimson Seedless grape vine was studied in 2012 and 2013 seasons, as an alternative
to traditional chemical compounds that are harmful to the environment to control
the pre and postharvest diseases. The vines were dipped in three levels of BABA
(200, 250, 300 ppm) two weeks before harvest. The linear growth and dry weight
of Botrytis cinerea isolated from Crimson Seedless grape were greatly
influenced by the increase in BABA concentration up to 300 ppm. In both seasons,
prolonging the marketing stage resulted in decreased in disease infection with
the increase in concentrations, at 300 ppm concentration, BABA gave the maximum
reduction in disease infection caused by Botrytis cinerea, in addition
to the improvement of fruit quality at harvest and during cold storage (for
60 days at 0±1°C with 90-95% RH), as well as 3 days marketing period
at room temperature. Clusters treated with 300 ppm BABA developed less decay
shatter and total loss. Moreover, it was more effective in rising SSC, titratable
acidity, total sugar and anthocyanin accumulation in the skin of berry during
cold storage conditions and marketing period compared with the other treatments.
While, BABA 250 ppm showed high berry firmness and adherence strength. 2014/06/07 - 06:53

We investigated the antifungal potentiality of multifunctional
novel picolinamide derivatives against various phytopathogens. Picolinic acid
is a microbial secondary metabolite reported to possess wide biological potential.
Picolonic acid was esterified, condensed with hydrazine hydrate and subsequent
refluxing with various substituted aromatic aldehydes to synthesize sixteen
novel substituted picolinamides. Synthesized novel compounds were characterized
by various physico-spectral techniques. Structure antifungal activity relationship
of the synthesized molecules was predicted by evaluating individual derivatives.
Picolinamide derivatives were found to possess significant antifungal activity
against the wide range of soil borne pathogens. Chloro substituted picolinamide
derivatives exhibited maximum antifungal activity against R. solani (ED50
29.08 μg mL-1) followed by A. alternata (ED50
33.90 μg mL-1). Antifungal bioassay results testify that these
compounds can be of interest in search for new fungicides. 2014/06/07 - 06:53

Bacillus subtilis B006 has been attempted in this study
to control wilt disease of cucumber. In order to clear its suppressing mechanism
in rhizosphere, population of Fusarium oxysporum f. sp. cucumerinum
J. H. Owen (Foc) and B006 in cucumber rhizosphere were determined using
real-time PCR. Real-time PCR program of B. subtilis B006 in soil was
established for first time with the limit as low as 78.0 CFU g-1.
Real-time PCR assays showed that combined use of B006 in substrate, drenching
during transplantation and hole application with organic fertilizer can improve
its colonization in rhizosphere by 10 times in comparison with its single use
in substrate. And its presence resulted in the decline of Foc number
over 10 times and 2 weeks delay of the disease development and reduction of
disease severity in comparison with the non-B006 treatment. Greenhouse test
showed that the addition of B006 powder in substrate can control cucumber wilt
effectively with the control efficacy of 53.6%, combined use of 30 mL B006 suspension
by drenching at the concentration of 106 CFU g-1 with
hole application of 10 g organic fertilizer per seedling during transplantation
resulted in the best control performance of 72.2%, while single use of organic
fertilizer only resulted in the control performance of 29.4% in comparison with
blank control. This study improves our understanding for the interaction of
B006 and Foc in cucumber rhizosphere further and provides us a suitable
application way of B. subtilis as a bioagent for cucumber wilt management. 2014/06/07 - 06:53

Experiment was conducted at BHU in the year 2012-13. Radial growth was not significantly different for most of the isolates. Seven DAI (days after inoculation) highest radial growth has obtained in isolate RF-1 (35.50 mm), Ten DAI maximum growth was observed in isolate EC-1 (52.00 mm) and Thirteen DAI maximum radial growth was same observed in two isolates IIVR and BHU-1 (88.75 mm). The maximum mean mycelial growth was observed in isolate IIVR (57.83 mm) followed by MF-4 (57.66 mm) and BHU-1 (56.83 mm). Isolates of A. solani depicted high variability in pigment production on PDA medium. Mycelial growth patterns were observed on PDA where BG RF-1 SF-1 MF-4 BHU-1 grew with circular margin with smooth surfaced colony and AF-2, PN-4, EC-1, BX-2 and IIVR isolates grew with irregular margin and rough surface. Five varieties of tomato were screened with 10 different isolates. The variety Selection-7 and H-86 were highly susceptible and susceptible, respectively with all the isolates tested. The variety Feb-2 was resistant while, the variety Flora Dade and Swarna Naveen were highly resistant with all the isolates. There was no significant difference between Flora Dade and Swarna Naveen. Out of 10 isolates, only three major groups were recorded on the basis of SAS analysis likewise Group-A isolates were highly virulent (MF-4 and PN-4), Group-C isolates indicate virulent (BG, AF-2, EC-1 and RF-1) and Group- E isolates were less virulent (BHU-1, IIVR, SF-1 and BX-2) with all the five varieties. 2014/06/07 - 06:53

The biocontrol potential of Trichoderma viride against anthracnose
pathogen Colletotrichum alienum was studied in vitro and under
greenhouse conditions. In vitro antagonism test carried out between T.
viride and C. alienum showed a radial growth inhibition of the pathogen
by 75% at 35°C. The greenhouse studies involved inoculation of healthy Swietenia
macrophylla seedlings with suspensions of T. viride and fungicide
(Carbendiazim) followed by addition of the pathogen, C. alienum inoculum
after three days. After inoculation the infected leaf area was measured weekly
and Area under the Disease Progress Curve (AUDPC) was calculated and compared
among the treatments. The results showed that T. viride (AUDPC = 120)
and fungicide (AUDPC = 93) significantly (p<0.05) reduced the disease compared
to the untreated control (AUDPC = 1200). T. viride significantly controlled
the pathogen on par with fungicide treatment. This study revealed that the application
of T. viride has good potential in controlling the anthracnose disease
of S. macrophylla. 2014/06/07 - 06:53

Bacillus subtilis S44 is a promising plant growth-promoting rhizobacterium
and a potent biocontrol agent isolated from cotton rhizosphere. The ituD
gene was cloned and identified from S44. A suicide vector containing ituD
gene from B. subtilis S44 was recombined into the B. subtilis
S44 chromosome to disrupt the ituD gene. Recombination was demonstrated
by PCR, antifungal activity and HPLC confirmed the loss of the ituD gene.
The growth rate of the recombinant is severely depressed compared with wild
type and tetracycline had no effect on the growth rate the mutant strains. Antifungal
activity in cell-free extracts of the recombinant has almost no antifungal activity
compared with the wild strain. HPLC analysis show that the wild strian produce
iturin A at an amount of 89.4 μg mL-1 while the ituD
mutant only 3.41 μg mL-1. In pot and plot tests, the control
effects of S44 treatment were 80.30 and 72.97%, respectively. The mutant strains
S1 and S2 exhibit no control effect of cotton Rhizoctoniosis. These results
suggest that the ituD gene was important for iturin A synthesis and
biocontrol activity of S44. 2014/04/25 - 21:41

The tri5 gene cluster is associated with production
of trichothecene B type mycotoxins in Fusarium graminearum and F.
culmorum. Multifunctional oxygenase and trichodiene synthase encoded by
tri4 and tri5 genes, respectively, belonging to this cluster are
responsible for production of trichothecenes. In this study, tri4 and
tri5 gene expression levels were determined in 14 F. graminearum and
24 F. culmorum isolates causing head blight in wheat, maize and barley
collected from different regions of Turkey. Isolates producing oxygenase and
trichodiene synthase in high levels were distinguished from low-producers using
two-step reverse-transcription comparative quantitative real-time PCR. Slope
values were -3.63, -3.4 and -3.4 for amplification of tri4, tri5 and
β-tubulin genes, respectively. Cp values were ranged from 17.08±0.0
to 38.82±1.66. The highest tri4 and tri5 expression levels
were determined in 4F isolate of F. graminearum. ΔΔCT ratios were
calculated as 0.1371 for tri4 gene and 0.865 for tri5 gene. However,
maximum tri4 and tri5 expressions were detected in 20F (ΔΔCT
= 0.2196) and 9F (ΔΔCT = 0.3761) isolates in F. culmorum, respectively.
Quantification of definite toxin content can contribute to determination of
pathogen infection grade and to gaining the information about fungal biomass
on field crops and their products. 2014/04/25 - 21:41

A variety of faba bean cultivars infected with BBTMV showed symptoms as severe mosaic, mottling, crinkling, size decline and malformation. Salicylic Acid (SA) application before inoculation specially 100 μM concentrate was reduced the virus symptoms. In Infected plants under all SA treatments were decreased the viral concentration, percentage of infection and severity of diseases compared with decreasing under BBTMV infection without SA treatments. Increase the level of SA play role important for resistance against BBTMV infection in all faba bean cultivars. Possessions of viral disease with SA application were tested after 21 days from inoculation measured up to healthy control on some protein characters include the quantity of protein bands, molecular weight of band and percentage of the protein band in all diverse faba bean cultivars within this investigation. The results showed that all SA treatments increased all properties of protein patterns. The highest increase was observed when seedling treated by 100 μM (SA and BBTMV) compared with uninfected control. The highest increase of protein contents was observed in infected cv. Sakha1 and lower increase was noticed in cv. Tribe White. In the largest parts of SA applications, the all protein characters were mentioned above an increased includes protein amounts and numbers. Total soluble proteins were accumulated when healthy plants were treated by SA. Stimulation of broad bean cultivars to BBTMV infection under SA application were observed in found many modifications in protein patterns. Probably, the polypeptides accumulation is depending on the SA level. The main purpose of this research was to invistegate the effects of BBTMV and SA treatments on symptoms development, virus concentrations, percentage of infections, disease severity, protein patterns in different broad bean leave cultivars, protein bands numbers, molecular weight bands and percentage of amounts in susceptible and tolerance broad bean cultivars. 2014/04/19 - 23:18

The efficacy of 13 plant products were evaluated against chilli fruit rot and
dieback incited by Colletotrichum capsici. Among them bulbs of A.
sativum (20%) and A. cepa (60%) and seed extract A. indica
60% gave complete inhibition of the pathogen and were on par with carbendazim
(0.1%) leaf extracts of D. metel, E. globulus and P. juliflora
at 60% concentration totally inhibited the mycelial growth of C. capsici.
Conidial germination of C. capsici was completely inhibited by A.
sativum 20%, E. globulus, D. metel 60% and P. juliflora
60%. Plant products at their respective MIC=s totally inhibited the sporulation
of C. capsici. Production of cellulolytic and pectinolytic enzymes the
pathogen was also inhibited maximum with fungicide carbendazim (0.1%), followed
by A. sativum and E. globulus. The same treatments recorded maximum
seed germination (17.74%), seedling vigour and maximum control of disease incidence.
Pots treated with A. sativum (20% conc.) recorded higher yield and fruit
characters such as increased fruit length (43.53 cm) and fruit weight (36.19
g). 2014/04/19 - 23:18

Alternaria blight caused by Alternaria brassicicola
(Schwein) Wiltshire and Alternaria brassicae (Berk) Sacc. is one
of the most serious diseases of Cauliflower [Brassica oleracea (L.) var.
botrytis] and Mustard [Brassica juncea L.] grown as edible vegetable
and oilseed crop, respectively in India. As resistance against these pathogens
is not found till now therefore, the exploration of the host-pathogen interaction
is much needed. In the present study, the cauliflower-A. brassicicola and
mustard-A. brassicae interactions were studied at microscopic level using
light and electron microscope. The initial infection processes involve conidia
germination, penetration and colonization on the plant surfaces. Several germ-tubes
developed from conidia and colonize extensively across the leaf surfaces. Penetration
in the plant surface, either directly through the epidermis or via stomata occurred
with occasional appressoria formation. Least aggressive A. brassicae
isolate was found to infect mustard leaf by spreading over epidermal cells only.
Finally, hyphae colonize the leaf cells forming network collapsing epidermal
cells to form necrotic lesions which may be due to release of toxin. 2014/04/19 - 23:18

Studies were carried out in screen house to determine the effects of different
inoculum densities (2,000 and 4,000 eggs of Meloidogyne javanica) and
different levels (15, 30, 45, 60 and 75 t ha-1) of leaf powder of
Hyptis suaveolens soil amendment on the pathogenicity of M. javanica
on African yam bean. Results showed that organic soil amendment with H. suaveolens
improved on the growth of plants infected with eggs of M. javanica as
against the infected plants but unamended. It was also observed in this study
that higher soil amendment levels (>30 t ha-1) led to sharp progressive
decline in the fresh shoot and root weights of amended plants, which indicates
possible phytotoxicity of H. suaveolens leaf powder at amendment levels
above 30 t ha-1. H. suaveolens leaf powder amendment reduced
significantly (p≤0.05) the number of galls, egg masses, gall index and egg
mass index as the amendment levels increased at both low and high inoculum densities.
M. javanica reduced significantly (p≤0.05) the number of nodules in
infected test plants compared to the uninfected controls. This study also revealed
that the pathogenicity of M. javanica was more at high inoculum density
generally. Conclusively, this study has shown that application of H. suaveolens
as soil amendment reduced the pathogenicity of M. javanica and improved
on the growth parameters of the test plant but at higher levels (above 30 t
ha-1) it became phytotoxic and highly nematicidal. 2014/04/19 - 23:18

The objective of this study was to evaluate the effect of acibenzolar-S-methyl tested at 5 concentrations (0, 1, 5, 25 and 100 μM a.i.) for its ability to protect papaya (Carica papaya) cv. Rainbow from black spot (Asperisporium caricae) following inoculation with the fungus. Effects of resistance induction treatment against black spot disease were evaluated by measuring the plant height and stem diameter. Disease symptoms were scored weekly by visually estimating disease severity of plants on the basis of a 5-class visual scale of 0 (no symptoms) to 4 (extensive lesions on leaves). Accumulation of defence-related proteins in papaya leaves were also analysed and compared. Results revealed that the level of protection against A. caricae was dose-dependent. Maximum reduction of the disease in leaves was obtained with 25-100 μM acibenzolar-S-methyl, with a time interval of 3 days between application of the activator and inoculation with the pathogen. The systemic resistance elicitation was characterized by an increase in 2 pathogenesis-related proteins, chitinase and β-1, 3-glucanase. These results indicate that acibenzolar-S-methyl induces partial resistance in papaya against black spot disease which may provide the grower a new option for integrated management of the disease. 2014/04/19 - 23:18

Outbreaks of illness due to human enteric pathogenic bacteria
via fresh vegetables warrant intensive research on changing strategies of these
bacteria in alterning their hosts for survival. The systemic infection of human
pathogenic bacteria in plants and the plant growth stage at which they establish
endophytic relationship is poorly understood. The issue is magnified in countries
like India where the dietary habits are changing and consumption of fresh fruits
and vegetables as salad has become a part in the everyday menu of most people.
Most of the human pathogenic enteric bacteria are generally characterized by
broad host ranges and these pathogens seem to exploit almost any change in human
ecology that provides new opportunities for transmission. Because plants are
not traditionally considered as hosts for human enteric pathogens, recent produce-associated
outbreaks highlight important deficiencies in our understanding of the ecology
of enteric pathogens outside of their human and animal hosts. This review focuses
on understanding the human enteric pathogens that have developed abilities to
colonize internal tissues of vegetables and fruits popularly consumed as salads,
how and when do they enter plants and where do they localize in plant tissues.
In addition, we have also highlighted the attempts made in detection and control
of these bacteria in plant hosts. This understanding will help develop strategies
towards vegetable food safety in a joint effort by agriculturalists, environmentalists,
food processing agencies, whole salers and retailers, which will ultimately
benefit every consumer. 2014/03/18 - 23:17

Four strains of plant growth promoting rhizobacteria (Bacillus
subtilis, Paenibacillus polymyxa, Pseudomonas fluorescens
and Pseudomonas putida) and Sinorhizobium meliloti were tested
for their antibiosis toward damping-off disease of growth and yield of the alfalfa
crop during 2010-2011 and 2011-2012 seasons. In vitro the four PGPR strains
produced hydrogen cyanide (HCN), indole-3-acetic acid (IAA), siderophore, solubilized
insoluble phosphate and showed protease and β-1,3-glucanase activities,
whereas S. meliloti produced IAA and solubilized insoluble phosphate
only. PGPR strains strongly inhibited growth of Fusarium oxysporum,
Fusarium solani and Rhizoctonia solani in vitro. Furthermore,
Ps. fluorescens was the most effective followed by P. polymyxa, B.
subtilis and Ps. putida respectively. Seed treatment with the tested
PGPR strains significantly reduced alfalfa damping-off diseases incidence compared
to untreated control under greenhouse and field conditions. Ps. fluorescens
and P. polymyxa combined with S. meliloti recorded the highest
reduction in diseases incidence. Under greenhouse conditions, uninoculated plant
recorded the lowest nodule number and biomass, while co-inoculation with S.
meliloti and mixture of the four tested strains recorded the highest values.
Same results were obtained when alfalfa seeds were treated by PGPR combined
with S. meliloti on Number of nodules, dry weights of nodules, as well
as plant height, tillers/m2 fresh, dry weight and protein content
of alfalfa plants under field conditions. Ps. fluorescens and P. polymyxa
combined with S. meliloti recorded the highest values followed by B.
subtilis and Ps. putida respectively. 2014/03/18 - 23:17

Potato cultivation is hampered by a host of factors among
which fungal diseases play a leading role. Nevertheless, our knowledge on phytofungal
diversity inciting diseases at the early developmental stages of potato is limited
at present to some few traditionally recognized pathotypes. In this present
study, potato farms were surveyed for two and a half years and predominant fungi
causing disease at the early stages of potato development were identified using
standard taxonomic monographs and ribosomal DNA locus. It was found that Ascomycetes
viz. Colletotrichum gloeosporioides, Cochliobolus lunatus, Aspergillus
terreus, Aspergillus fumigatus, Nigrospora oryzae, Fusarium culmorum,
Pestalotiopsis vismiae, Phomopsis asparagi, Dothiorella gregaria, Didymella
cucurbitacearum, Stagonosporopsis cucurbitacearum and Penicillium citrinum
incite diseases of potato at the early developmental stages. This study
provide a comprehensive overview of the genetic diversity of Ascomycetes thriving
on potato plants and evidence that Aspergillus species are harmful pathogens
causing loses to potato cultivation. 2014/03/18 - 23:17

Several advanced tests for detection of Ralstonia solanacearum
phylotype II, sequevar I (race 3 biovar 2) in different habitats are nowadays
developed. The immunofluorescent antibody staining techniques (IFAS), along
with enzyme linked immunosorbent assay (ELISA) have been widely practiced. Using
IFAS, however, under certain circumstances produced non-specific reactions.
In the present study, a total of suspected 711 bacterial isolates recovered
over four years period (2009-2012) of routine testing of potato crop in PBRP
laboratories, Egypt, were subject to further determinations. All these isolates
were tested by IFAS using internationally approved antiserum brand to detect
R. solanacearum. These isolates were preliminary screened on Semi Selective
Media of South Africa (SMSA) medium for presumptive detection of R. solanacearum.
Colonies showing characteristics morphology of the pathogen in concern were
scored for 206 isolates on SMSA medium. These characteristically screened isolates
were physiologically and biochemically tested to confirm identity to R. solanacearum.
A sum of 505 bacterial isolates devoiding the described characteristics of the
pathogen were categorized into 7 groups according to their gram-staining reaction,
cell morphology and cultural characteristics. Each group embraces a tentatively
similar isolates according to motility, catalase and oxidase test(s) in principal.
The results of Biolog identification revealed the following species of the cross-reacting
bacteria that being affiliated to different families: Acinetobacter calcoaceticus,
Aeromonas caviae, Moraxella osloensis, Pseudomonas fluorescens,
Pseudomonas putida, Pseudomonas corrugata, Pseudomonas mendocina,
Pseudomonas tolaasii, Salmonella typhimurium, Serratia proteamaculans,
Shewanella algae, Sphingobacterium multivorum and Bacillus maroccanus.
The aforementioned identified bacteria were tentatively tested for the possible
pathogenic potential to plant as shown by causing soft rot in potato tubers
and inducing Hypersensitive Reaction (HR) in leaves of Burley tobacco plants. 2014/03/18 - 23:17

Tobacco mosaic virus (TMV) and Potato virus Y (PVY) are two destructive plant viruses which cause significant economic losses to tobacco. Breeding resistant cultivars is one of the most important strategies to control these viruses. In this study, the responses to TMV and PVY of 22 tobacco cultivars were evaluated based on resistance index and virus titre obtained from ELISA in both greenhouses and fields during five years (2007-2011). Nicotiana glutinosa resistant to TMV and Virgin A Mutant resistant to PVY were used as resistant checks; NC89 susceptible to both TMV and PVY was used as the susceptible check. The results showed that there were significant differences in disease index and ELISA value among the 22 tobacco cultivars after inoculation. Specifically, 2 cultivars (Coker86 and Jiyan5) were identified to be resistant or moderate resistant to TMV and 3 cultivars (Liaoyan8, Jinxing6007 and Qinyan98) to PVY, while the other cultivars were susceptible or moderate susceptible to TMV or PVY. The resistant cultivars may be used as resistant resources to TMV and PVY in future breeding projects. 2014/03/18 - 23:17

A study was carried out to establish on one hand, the genetic
diversity of the populations of Pyricularia oryzea at Abomey Calavi and
the other, to find out the favorable culture media for mass production of the
conidia and the mycelium of P. oryzea for the laboratory techniques.
Thus, trapping virulence races present in the prospected ecosystem in Abomey-Calavi
helped to highlight the fact that the resistance genes: Piz-t, Piks, Pik-p,
Pi1, Pi5 (t), Pi7, Pia, Pish and Pik were overcome by a large section of the
pathogen population. Virulence genes that are capable of overcoming resistant
genes Pii, Pi9, Pi33, Pi5 (t) Pi7 and Pikm are however absent or
rare. The latter represented the genes that were effective against the pathogen
population studied. On the other hand, this study showed that Pi5 and Pi7 gene
association, which is individually ineffective, has conferred a durable blast
resistance observed in Moroberekan. Four operational conditions were selected
on the basis of the spores quantities produced and the fastness of the mycelium
growth. The addition of starch in the medium does not influence the fungus mycelium
growth. But this growth is clearly influenced by extract doses of yeast. The
best sporulation is obtained for culture media consisting of 20 g of starch
and 2 g of yeast extract, 10 g of starch and 2 g of yeast extract L-1. 2014/03/18 - 23:17

Seedling blight caused by Rhizoctonia solani Kühn
substantially reduces stand establishment and seed yield of canola (Brassica
napus L.) in western Canada. The effect of crop residue on soil populations
of R. solani and canola seedling blight was examined under field, greenhouse
and laboratory conditions. Field plots were established with inoculation or
noninoculation with R. solani as the main plot and barley, canola, oat
and field pea residues as the sub-plots. Soil samples were collected from each
subplot for analysis in a greenhouse bioassay and laboratory assay of R.
solani population before seeding canola. The crop residue effect was not
significant. Under inoculation with R. solani, the yield was consistently
greater when canola was grown on barley residue compared to the canola residue
over two-year trials, although oat and pea residue contributed to greater yield.
Without inoculation, canola yield was greatest when grown on barley residue,
intermediate on oat and pea and the least on canola in the first trial and in
the second trial greater yield was obtained on barley and oat residues compared
to other residues. In the greenhouse bioassay, canola seedling emergence was
greater, while damping off and root rot were less severe, following barley or
oat compared to canola or field pea in both inoculated and non-inoculated treatments.
Populations of Rhizoctonia were lower following barley or oat relative
to canola or field pea. Crop rotation and incorporation of barley or oat residue
between canola crops may be a useful strategy to reduce seedling blight of canola. 2014/03/18 - 23:17

Onion (Allium cepa L.) is one of the most important
vegetable cum condiment crop of family Alliaceae, grown in all the parts
of India. Onion bulbs and green onions both are rich in minerals, proteins and
ascorbic acid. Onion is used throughout the year in the form of salad or condiment
or for cooking with other vegetables. Onion is also used for making pickles
in vinegar or brine. Its use in soups and souce is very common. Onion has several
medicinal uses, its use in the case of sun strokes is known world over. Basal
rot of onion caused by Fusarium oxysporum is a wide spread disease observed
in nurseries as well as in field in the vicinity of Jobner, which causes losses
at all the stages of crop growth right from germination to till harvest and
also in storage. The efficacy of different fungicide, Benlate, Bavistin, Blitox,
Captan and Thiram of different concentrations (50, 100, 200 and 300 ppm) and
organic amendments neem cake, mustard cake, groundnut cake, vermicompost and
goat and sheep manure of different concentrations (10, 20, 30%). Benlate was
found most effective with complete inhibition of mycelial growth of the fungus
at 200 and 300 ppm concentrations followed by Bavistin and Blitox. In organic
amendements neem cake was found most effective in inhibiting the mycelial growth
of Fusarium oxysporum and it was followed by mustasrd cake. 2014/03/18 - 23:17

Yellow mosaic disease caused by Mungbean yellow mosaic
India virus (MYMIV) is one of the important biotic constraints to mungbean
and urdbean production. Information on the weed hosts of MYMIV is meager. Ageratum
conyzoides, a common weed in and around the agricultural fields throughout
the year is often seen with yellow vein symptoms. This prompted us to look into
the possibility of A. conyzoides acting as an alternate host of MYMIV.
The present study deals with the characterization of MYMIV in A. conyzoides
from four different locations in and around Kanpur. Of the forty plants of A.
conyzoides showing yellow vein symptoms subjected to the PCR based detection
of viruses causing yellow mosaic disease in pulse crops, 52.5% were found positive
with primers specific to MYMIV. None of the samples gave any amplification with
primers specific to Mungbean yellow mosaic virus and Horsegram yellow
mosaic virus. Presence of DNA A and DNA B of MYMIV was also confirmed by
using specific restriction enzymes to release ~2.7kb DNA fragments from the
product of rolling circle amplification. It is evident from the above two detection
methods that A. conyzoides is a new host of MYMIV. The virus was successfully
transmitted by whiteflies from weed to cultivated hosts (mungbean and urdbean)
and induced typical yellow mosaic symptoms. Since this is a common weed growing
throughout the year, it might be serving as an important source of primary inoculum
of this virus for recurrence of yellow mosaic disease in grain legumes in northern
India. 2014/03/18 - 23:17

This study examines the fungicidal activity of a medium-chain fatty acids mixture comprising caprylic acid (C8:0), pelargonic acid (C9:0) and capric acid (C10:0), against Rhizoctonia solani, Phytophthora infestans, Colletotrichum gloeosporioides, Botrytis cinerea, Fusarium oxysporum and Sphaerotheca cucurbitae. The mixture of caprylic, pelargonic and capric acids (2/5/3, w/w/w) is prepared into a micro-emulsion concentrate and tested for its inhibitory effect on fungal growth using disc diffusion method except for S. cucurbitae using pot bioassay method. Results show that the fatty acids mixture is self-stabilized under either 4°C during a seven-day-storage or 54°C during fortnight. The doses of the mixed fatty acids completely inhibiting the mycelial growth are 100 ppm for P. infestans and 125 ppm C. gloeosporioides after three days and 200 ppm for B. cinerea after 4 days. A dose of 100 ppm reduces the mycelial growth in R. solani by 93.7% after 4 days and that in F. oxysporum by 92.9% after 3 days. For S. cucurbitae, a dose of 250 ppm results in a control effect of 81.0% in the pot bioassay. Our study provides so far the first report of the fungicidal activity of medium-chain saturated fatty acids mixture at relative low dosage rates. 2014/03/18 - 23:17

The objective of this study was to evaluate the individual
and combined efficacy of Pseudomonas fluorescens (EPI-5, KPI-7, ANR-2
and RTM-3) and Bacillus subtilis (KGI-4, PYR-3 and OCM-6) strains to
promote the growth and yield parameters of tomato and to manage Fusarium
wilt disease under in vitro and greenhouse conditions. The dominant pathogen
which causes Fusarium wilt of tomato, was isolated and identified as
Fusarium oxysporum f. sp. lycopersici (FOL). Twenty five
native bacterial antagonists were isolated from healthy tomato rhizosphere soil
in different geographical regions. Under in vitro conditions, the results
revealed that the combined application of EPI (Pf-5)+KGI(Bs-4)+KPI (Pf-7) was
found to effectively inhibit the mycelial growth of the pathogen (by 40%) when
compared to application of individual strains of the bacterial antagonists.
The above strains of P. fluorescens and B. subtilis were found
compatible. Under greenhouse conditions, the combined application of EPI (Pf-5)+KGI
(Bs-4)+KPI (Pf-7) exhibited the highest disease reduction. Also, tomato plants
treated with EPI (Pf-5)+KGI (Bs-4)+KPI (Pf-7) strains showed a significant stimulatory
effect on plant height and increased the dry weight of tomato plants up to 27%
in comparison to the non-bacterized control. The combined strains also increased
tomato fruit weight. It could be concluded that synergistic consortia of beneficial
bacteria isolated from rhizosphere soil are perfectly able to promote plant
growth and could be exploited for sustainable management of soil borne diseases
especially, Fusarium wilt of tomato. 2013/12/24 - 08:49

The present study investigated the extent of Onion Yellow Dwarf disease (OYD) spread under two types of farming systems using the growing-on method of onion dry bulbs collected from four localities in four different States in Sudan. The study was also intended to assess the influence of isolation distance and wind direction in relation to source of infection on disease incidence and the subsequent plant vigour and bulb yield. In addition, the effect of insecticide spray and plant barrier around onion plots on disease development and virus dissemination were also investigated. These studies were carried out under the natural infection pressure prevailing in the area of experimentation. With regard to the influence of orientation of the test ridges in relation to source of infection (the infector line), OYD disease incidence (60 days after transplanting) was found to be significantly greater in ridges grown down-wind the infector line than in up-wind ridges. It was progressively declining with increasing distance from the infector line. Consequently, the plant vigour and bulb yield were found to be improved significantly in up-wind ridges and as the isolation distance was increased from the infector line. Although, spraying onion plants with Confidor® 200 (a pyrethroid insecticide) caused non-significant reductions of virus (OYDV) incidence, yet it significantly enhanced the plant height and bulb yield. The results also indicated that the plant barrier using corn plants constituted an effective hindrance against OYDV spread. The combination of the barrier and insecticide spray gave the lowest OYDV incidence compared to non-bordered/non-sprayed control plots. 2013/12/24 - 08:49

Oil palm is an economically important crop in Thailand with
its cultivation concentrated in the southern provinces. Diseases and disorders
are the major cause of yield and quality losses to oil palm plantations. The
objective of this study was to provide updated information on and to evaluate
the geographical distribution of oil palm diseases and disorders in southern
Thailand. A survey of oil palm plantations in southern Thailand was conducted
during the years 2010-2012, to record diseases and disorders of the crop. This
revealed a variety of oil palm diseases, including algal, bacterial and fungal
diseases; macro and micronutrient deficiency problems and genetic disorders.
Three diseases, namely brown germ, Curvularia leaf blight and Ganoderma
basal stem rot, were classified as major diseases during the survey period.
Brown germ and seed rot were the most destructive, affecting the seed germination
process. The fungi that were frequently isolated from the collected samples
belonged to the genera of Aspergillus spp., Fusarium spp., Mucor
spp., Penicillium spp., Schizophyllum commune and sterile
hyphomycetes. Curvularia leaf spot caused by C. oryzae was widespread
at nursery seedling stage, while the basal stem rot caused by G. boninense
was very destructive at the fruiting stage in the field. This report describes
the incidence rates, disease symptoms and the fungi isolated from symptomatic
tissue. 2013/12/24 - 08:49

Studies were conducted to evaluate the seed quality changes
during storage due to fungal infection, at the Department of Seed Science and
Technology, Tamil Nadu Agricultural University, Coimbatore. The seed materials
of groundnut variety VRI 2 collected from three different locations of Tamil
Nadu viz., Vridhachalam (L1), Thindivanam (L2) and Villupuram
(L3) were subjected to experimentation. During storage, seed quality
parameters such as germination and vigour index decreased from 84-79% and 2581-2005,
respectively while moisture content increased from 7.1-8%. The investigation
revealed that the seeds collected from Tindivanam showed better seed quality
with 81% germination, 7.8% moisture content and vigour index of 2216, even after
seven months of storage. 2013/12/24 - 08:49

Field pea rust caused by Uromyces viciae-fabae (Pers.)
de Bary is one of the most important diseases adversely affecting its yield
in India. The present investigation was conducted to find out some common, inexpensive,
non-toxic and simple chemical compounds as abiotic elicitors of Pisum sativum
L. cv. ‘Aparana’ in relation to active defense response as possible
alternative in the management of field pea rust. Forty-three chemicals alone
and their combinations were tested as spray/basal treatment in Randomized Block
Design with 3 replications during the year 2000-2003 to find out their role
in induction of resistance. Out of 15 micronutrients tested only CuSO4
and Na2B4O7 were found most effective with
72-78% reduction in rust severity, 38-57% reduction in size of pustules and
83-92% reduction in number of pustules per leaf of pea. Among micronutrients
combinations A+KAl(SO4)2+CuSO4 followed by
were best in reducing disease severity in comparison to control. Among
tested chloride form of micronutrient, organic acid and chemical the KCl, CuCl2,
sodium azide and sucrose were found most efficient in respect to seed yield
and reduction in rust severity. The results of the present study showed a strong
possibility to protect fieldpea through their natural defence system by using
inducer chemicals as integration in sustainable plant disease management strategy. 2013/06/21 - 22:35

Several surfactants, plant extracts and fatty acids were tested for stimulation of conidial germination, appressorial formation and virulence of Colletotrichum truncatum, a bioherbicide of the weed, hemp sesbania (Sesbania exaltata). The commercial surfactants (Tweens® 40, 60, 80, 85 and Myvatex® 60) at concentrations of 0.25 to 1.0% (v/v), stimulated germination, but these effects were not exclusively related to their hydrophylic-lipophylic balance values. The stimulatory surfactants were also tested for germination and virulence of C. truncatum when formulated with the conidia and applied to hemp sesbania seedlings. Conidia formulated in either water, a surfactant or, an emulsion of refined corn oil were ineffective on the plant in the absence of dew or when dew was delayed. However, formulations of conidia combined with surfactant in emulsified refined corn oil did exhibit bioherbicidal activity when adequate dew or free-moisture was unavailable. This is important since previous reports indicated that refined corn oil did not enhance bioherbicidal activity, whereas unrefined corn oil promoted pathogen germination and efficacy of C. truncatum. The fatty acids tested had little or no effect on conidial germination but, aqueous extracts of several plant species including pathogen hosts and non-hosts, stimulated germination. Appressorial formation influenced by the surfactants did not necessarily reflect the disease rating on hemp sesbania seedlings. Overall, results show that formulations containing an emulsion of conidia, a surfactant and refined corn oil have potential for enhancement of the efficacy of C. truncatum. 2013/06/21 - 22:35

Tomato (Lycopersicon esculentum Mill.) is one of the
most widely grown vegetables in the world including Ethiopia. However, its production
is constrained by different abiotic and biotic factors. Among biotic factors,
bacterial wilt caused by Ralstonia solanacearum is one of the most important
pathogens, threatening the production of tomato and potato in Ethiopia. So far
there is no single means that would totally manage the disease and provide an
absolute cure or fully protect host plants against the pathogen. Hence it is
important to look for alternative mechanisms of disease management that can
be used as an integrated disease management scheme. This study was, therefore,
initiated with the objectives of evaluating the antibacterial activities of
aqueous and solvent (acetone and methanol) extracts of five invasive alien species
(Eichhorina crassipes, Mimosa diplotricha, Lantana camara and Prosopis
juliflora) against R. solanacearum. In vitro antibacterial
test was carried out in disc diffusion sensitivity test in a completely randomized
design with three replications. It is evident from the result that most of the
plant extracts exhibited significant inhibition of the bacterial growth compared
with the control. Aqueous extract of E. crassipes provided the highest
inhibition zone (26 mm), followed by M. diplotricha (14 mm). After in
vitro screening, four promising invasive alien species extracts (aqueous
extracts of E. crassipes, M. diplotricha, L. camara and methanolic extract
of P. juliflora) with inhibition diameter>10 mm were selected and
Minimum Inhibitory Concentration was assessed in vitro. They were also
evaluated on tomato plants by applying the botanicals at three time of application
(at the time of inoculation and 2-days before and after inoculation). The result
of current study revealed that most of the treatment combinations significantly
reduced percent disease severity index, but the inhibitory activities of tested
plant species were reliant on type of plant species and their application time.
More than 91% reduction in percent severity index of bacterial wilt was observed
in tomato plants treated with leaf extract of E. crassipes when it was
applied at a time of inoculation. The result suggested a need to continue research
on invasive alien species extracts and determine their active principles to
develop environmentally friendly management approach against bacterial wilt
of tomato. 2013/06/21 - 22:35

Lentil is one of the major sources of protein for vegetarian population and the second most important legume crops of Indo-Gangetic Plain (IGP) in India. Powdery mildew (Erysiphe trifolii) is one of the important fungal disease of lentil grossly affect foliage as well as in severe cases stems and pods also and causes reduction in crop yield and quality of seed. Mineral nutrition especially sulphurs to the great extent and moderately to zinc, plays a very important role in powdery mildew management. A field experiment was conducted at ICAR Research Complex of Eastern Region Patna during 2008-09 to 2010-11 to ascertain the role of sulphur and zinc in rice-lentil cropping system. Four levels of sulphur and zinc (Sixteen treatments combination) were tested in randomized block design replicated thrice. Both the nutrients were applied to rice and residual response was ascertained to rice and lentil in sequence. Least (5.5%) disease index was recorded in the plots received residual sulphur 40 kg and Zn 5 kg per ha. Whereas highest disease index (15.5%) was recorded in the plots having no residual sulphur and zinc. Maximum lentil seed yield (1147 kg ha-1) was recorded with 30 kg residual sulphur whereas minimum seed yield (1015 kg ha-1) was noticed with no application of sulphur in the previous crop in cropping system. Application of 40 kg sulphur in combination with 6 kg zinc to the previous rice crop is most ideal; not only for rice-lentil system productivity, but it also provide better agronomical option to manage powdery mildew disease in lentil. Efficient management of these nutrients to manage disease and to boost crop resistance is crucial as higher sulphur and Zn rates not only improve powdery mildew management of lentil but its production and productivity, which proves the roles of sulphur and Zn in nutrient and disease interactions as well. 2013/06/21 - 22:35

Fusarium oxysporum is a main agriculture pathogen which
is responsible for wilting in cucumber, muskmelon and watermelon. In order to
study the genetic relationship and phylogeny of Fusarium oxysporum, 36
isolates were obtained from Liaoning province. The genetic relationship of Fusarium
was determined by using EF-1α and β-tubulin DNA sequencing as well
as a universally primed polymerase chain reaction (UP-PCR) analyses. The results
show that all 36 isolates were identified as being infected with F. oxysporum
by using the specific primers FOF1 and FOR1. Based on the combined sequence
and UP-PCR data, the 36 isolates and GenBank isolates were classified into three
major groups (Lineage1-3). These groups corresponded with the three clades of
F. oxysporum. Inspection of the sequence data revealed Lineage 1 and
Lineage 2 had similar sequences whereas Lineage 3 was significantly different
from the other two. And this finding matched the results of UP-PCR analysis.
However, the GenBank isolates were classified into Lineage 1 and none of the
three techniques applied in this study provided host-related resolution for
the pathotype isolates or the geographic origin of isolates. This study confirmed
that phylogenetic groups have little connection with virulent groups. 2013/06/21 - 22:35

In vitro experiments were carried out with Phaeoisariopsis
personata isolate to determine its sensitivity/tolerance to different fungicides
viz., Tebuconazole (0.05%), Tebuconazole (0.10%), Tebuconazole (0.15%), Tebuconazole
(0.20%), Tebuconazole (0.40%), Folicur (0.10%) and Mancozeb (0.30%) using poisoned
food technique both in solid and liquid medium. In the solid medium method,
visual observation was taken 20 days after inoculation of the pathogen. There
was no significant difference among the different fungicides in their efficacy
against P. personata, compared to control. In case of liquid medium the
observations were taken after 25 days of inoculation and the results are presented.
There was significant difference between the fungicides in per cent inhibition
against the mycelial growth of the pathogen, P. personata. Among all
the fungicides, Tebuconazole 0.4% (87.97%t) showed maximum inhibition followed
by Tebuconazole 0.2% (85.24%) and Tebuconazole 0.15% (83.50%), among these Tebuconazole
0.15% was found to be optimum. Application of fungicidal sprays influenced the
development of Cercospora leaf spot and reduced its intensity. Among
these applications of different fungicides, Tebuconazole (0.15%) gave best result
and reduced the disease intensity to 52.42%. Area under disease progress curve
(AUDPC) greatly varied among different fungicidal treatments and showed significant
difference in yield data. Impact of fungicides used for disease control was
apparent on yield per plot. Tebuconazole (0.15%) gave best result and increased
yield up to 67% as compared to 39% increase by Tebuconazole (0.10 %). 2013/06/21 - 22:35

The most destructive disease of Para rubber seedling is a leaf fall caused by Phytophthora botryosa. The bioactivity of chitosan against P. botryosa infection was studied in vitro. The growth rates of P. botryosa in potato dextrose agar were determined with different concentrations of chitosan. A chitosan concentration of 0.5 mg mL-1 was sufficient to cause clear growth inhibition (about 87% reduction in diameter). Mycelia and oogonia wilt were observed in scanning electron micrographs of P. botryosa. The biodegradable chitosan therefore inhibits the in vitro growth of P. botryosa and may have potential for practical disease management of leaf fall. 2013/06/21 - 22:35