Rot Disease Research Articles

PENEKANAN PERKEMBANGAN PENYAKIT BUSUK BATANG VANILI (FUSARIUM OXYSPORUM F.SP. VANILLAE) MELALUI SELEKSI ASAM FUSARAT SECARA IN VITRO

The most biological constrain on Vanilla planifolia plantation recently was caused by epidemical disease that laterdecrease vanilla production. The most important disease on vanilla is foot rot disease caused by Fusarium oxysporum f. sp.vanillae. So far, the disease has not been successfully controlled although some experiments had been conducted. Onealternative method has been introduced by using a new cultivar which was resistance to Fusarium). A mutant vanilla to thefungus has been initiated by in vitro selection on medium containing fusaric acid. The aims of this research were: (1) to investigate effective concentration of fusaric acid used for in vitro selection, (2) to characterize mutants which have been set up and also to test those mutants for their resistance to the fungus. The results showed that: (1) fusaric acid at the concentration of 110 ppm effectively suppressed the disease intensity up to 25% compared to the concentration of 90 ppm and 100 ppm. In other words, 110 ppm of fusaric acid has increased the category criterion from moderate to resistant, (2) there was an increase of the total phenol content and thickness of lignin in vanilla stem, and (3) the protein profile of vanilla plantlet was different from the control. There was an initiation of a new band of about 18 kD in a mutant predicted as a protein which is responsible for vanilla resistance to Fusarium.

Evaluation of botanicals as biopesticides on the growth of Fusarium verticillioides causing rot diseases and fumonisin production of maize

Partially (Pp) and completely purified (Cp) methanolic extracts of leaves of Cassia alata,Cymbopogon citratus (lemongrass), Mangifera indica (mango), Carica papaya (pawpaw),Citrus limon (lemon), fruits of Xylopia aethiopica, seeds of Aframomum melegueta (alligator pepper), Citrus aurantifolia (lime), Garcinia kola (bitter kola), Piper guineense (brown pepper), and rhizome of Zingiber officinale (ginger) were tested for antimicrobial activity using the poisoned medium and disc diffusion assay techniques on maize mycotoxigenic fungus:Fusarium verticillioides. The Pp extracts of P. guineense, G. kola and A. melegueta showed consistent higher growth inhibitions at 2, 5 and 7 days after incubation, while C. papaya and M. indica had the least activities. It was observed that these extracts completely inhibited the mycelial growth of the fungus at 2 days after incubation and produced growth reduction of 82, 80 and 73% respectively. The Cp extracts of P. guineense, G. kola, and A. melegueta also exhibited consistently higher inhibitions at 3, 5, and 7 days after incubation, while C. papaya andM. indica had no inhibitory activity. The three extracts produced reduction of mycelial growth of 76, 54 and 43% respectively. CP extracts of the plant material showed minimum inhibitory activity against F. verticillioides at 10 to 250 mgml-1 concentration level. The thin layer chromatographic analysis of the plant extracts showed different fractions, while 4 and 1 fractions of P. guineense and A. melegueta showed bioactivity respectively, which may be the important factor in causing the inhibitory effect. P. guineense, G. kola and A. meleguetashowed potential and could be successfully used as environmentally-friendly, cheap, available, effective and sustainable alternative biopesticides. Key words: Alternative pesticides, antifungal, Fusarium verticillioides, maize, medicinal plants

Biological Control of Damping-off, Root Rot and Wilt Diseases of Faba Bean by Cyanobacteria (Blue-Green Algal) Culture Filtrate

Biological Control of Damping-off, Root Rot and Wilt Diseases of Faba Bean by Cyanobacteria (Blue-Green Algal) Culture Filtrate

A Novel Multidomain Polyketide Synthase Is Essential for Zeamine Production and the Virulence of Dickeya zeae

Dickeya zeae is the causal agent of the rice foot rot disease, but its mechanism of infection remains largely unknown. In this study, we identified and characterized a novel gene designated as zmsA. The gene encodes a large protein of 2,346 amino acids in length, which consists of multidomains arranged in the order of N-terminus, β-ketoacyl synthase, acyl transferase, acyl carrier protein, β-ketoacyl reductase, dehydratase. This multidomain structure and sequence alignment analysis suggest that ZmsA is a member of the polyketide synthase family. Mutation of zmsA abolished antimicrobial activity and attenuated the virulence of D. zeae. To determine the relationship between antimicrobial activity and virulence, active compounds were purified from D. zeae EC1 and were structurally characterized. This led to identification of two polyamino compounds, i.e., zeamine and zeamine II, that were phytotoxins and potent antibiotics. These results have established the essential role of ZmsA in zeamine biosynthesis and presented a new insight on the molecular mechanisms of D. zeae pathogenicity.

Antagonistic Mechanism of Fusarium Oxysporum of Soybean Root Rot by Bacillus Subtilis

. Fusarium oxysporum is a soil-borne fungus that infects soybean roots and causes soybean root rot, a widespread and destructive soybean disease. The potential strain X6 belonged to Bacillus subtilis for controlling soybean root rot. And antagonistic mechanism of the pathogenic Fusarium oxysporum of soybean root rot by B. subtilis X6 was investigated. The antagonistic mechanism of strain X6 againt F. oxysporum can effectively inhibit mycelial growth, spores bearing and germination. After treated with metabolic product of strain X6, protoplast from the hyphae became abnormal. The activity effect of metabolic product of strain X6 was sensitive to temperature. So the study lay the groundwork for further research and application.

Influence of bio-inoculants on the control of root rot and wilt disease of pyrethrum caused by Rhizoctonia solani

The effect of four bio-inoculants namely, Glomus aggregatum, Streptomyces sp., Bacillus subtilis and Trichoderma harzianum and a fungicide, Ridomil-mancozeb was evaluated on the biomass production and control of root rot and wilt disease under glasshouse conditions. Results showed that 21-day- prior inoculation with G. aggregatum was most effective where none of the treated plants produced disease symptoms and interestingly their growth was increased by 39.4%. The colonisation by G. aggregatum (>80%) also increased P concentration in shoot. While, similar treatment with Streptomyces sp., B. subtilis, T. harzianum and Ridomil-mancozeb individually failed to produce any significant effect over Rhizoctonia solani inoculated control, where all inoculated plant died, prematurely. The simultaneous and 3-day-post treatments of G. aggregatum were non-effective but simultaneous treatment with Streptomyces sp. produced 70% disease control, while B. subtilis and T. harzianum individually provided 50% control. Their effects were either better or at par when compared with the simultaneous treatment of Ridomil-mancozeb. In 3-day-post treatment, Streptomyces, B. subtilis and Ridomil-mancozeb individually provided 50% disease control, whereas T. harzianum was least effective as it could protect only 25% plants against infection. The results reveals that 15 days prior treatment of G. aggregatum can significantly controls the root rot and wilt disease of pyrethrum. Further, treatment of Streptomyces can also serve the next effective post infection control method.

Antagonistic interactions between fungal rice pathogenFusarium Verticillioides (Sacc.) Nirenberg andTrichoderma harzianum Rifai

Trichoderma harzianum has been found to be a competitor and mycoparasite ofFusarium verticillioides which causes foot rot disease on rice. The experiment was undertaken macroscopically and microscopically. In total 6 treatments were performed combining three water activities (0.95, 0.98, 0.995) and two temperatures (15 and 25 °C). At all conditions tested, except at 0.95a w and 15 °C.Trichoderma harzianum acted as biocontrol agent trough two synergistic mechanisms — competition and mycoparasitism — overF. verticillioides. At 0.95a w and 15 °C mutual antagonism by contact was observed. The effect of abiotic factors water activity and temperature on fungal growth was determined.

Endophytic bacterial flora in root and stem tissues of black pepper (Piper nigrumL.) genotype: isolation, identification and evaluation againstPhytophthora capsici

To isolate and identify black pepper (Piper nigrum L) associated endophytic bacteria antagonistic to Phytophthora capsici causing foot rot disease. Endophytic bacteria (74) were isolated, characterized and evaluated against P. capsici. Six genera belong to Pseudomonas spp (20 strains), Serratia (1 strain), Bacillus spp. (22 strains), Arthrobacter spp. (15 strains), Micrococcus spp. (7 strains), Curtobacterium sp. (1 strain) and eight unidentified strains were isolated from internal tissues of root and stem. Three isolates, IISRBP 35, IISRBP 25 and IISRBP 17 were found effective for Phytophthora suppression in multilevel screening assays which recorded over 70% disease suppression in greenhouse trials. A species closest match (99% similarity) of IISRBP 35 was established as Pseudomonas aeruginosa (Pseudomonas EF568931), IISRBP 25 as P. putida (Pseudomonas EF568932), and IISRBP 17 as Bacillus megaterium (B. megaterium EU071712) based on 16S rDNA sequencing. Black pepper associated P. aeruginosa, P. putida and B. megaterium were identified as effective antagonistic endophytes for biological control of Phytophthora foot rot in black pepper. This work provides the first evidence for endophytic bacterial diversity in black pepper stem and roots, with biocontrol potential against P. capsici infection.

Comparison of photocatalytic activities of various dye-modified TiO 2 thin films under visible light

Owing to the large band gap energy of 3.2eV, pure TiO 2 film operates as an efficient photocatalyst under UV light irradiation and exhibits no photocatalytic activity under the visible spectral region. UV is only about 3% of the light existing in the solar spectrum. Currently, the red-shift in the band gap energy induced by dye-modified TiO 2 film is one of the most popular and economic processes for improving the drawback in TiO 2 photocatalyst. Therefore, we assess the photocatalytic efficiency of dye-modified TiO 2 thin film using various dye molecules such as Eosin Y, Safranine O and tris-2, 2′-bipyridyl dichlororuthenium (II) hexahydrate (Rubpy) using the sol–gel process under visible light ( λ > 400 nm). These results showed that TiO 2 thin film modified with Safranine O dye had the best photodegrading efficiency under visible light irradiation. The photocatalytic inactivation of Safranine O and Eosin Y dye-modified TiO 2 thin films against phytopathogenic bacteria including Enterobacter cloacae SM1 and Erwinia carotovora subsp. carotovora 3 which cause severe soft/basal rot disease in vegetable crops in Taiwan were all more than 90% after irradiation with visible light for 60min. The evidence suggests that the dye-modified TiO 2 thin film under visible light irradiation has potential for plant protection applications in hydroponic systems.

Treatment of foot rot in free-ranging mouflon (Ovis gmelini musimon) populations—does it make sense?

Prevalence and incidence of foot rot disease in free-ranging and captive bovine wild ruminant populations are increasing worldwide. Even species in which the disease has not been described in the past are presently affected by the co-working pathogens Dichelobacter nodosus and Fusobacterium necrophorum. This paper discusses disease control measures and the expense for a successful treatment of affected populations of mouflon. The rationale and perspectives of treating foot rot disease in wild mouflons are discussed.

IDENTIFIKASI CENDAWAN PATOGENIK PENYEBAB PENYAKIT HAWAR DAUN DAN BUSUK SULUR PADA TUMBUHAN ARISTOLOCHIA

<p><em>Pathogenic fungus cause leaf blight and shaped-rotten disease, which will decrease the quality, quantity and condition of Aristolochia plant. The plant plays an important role for conservation of the bird wing butterfly. The distribution of the bird wing butterfly depends on the condition of Aristolochia in that area. Identification of pathogenic fungus is very important because the disturbed Aristolochia plant give an indirect threat for the bird wing butterfly too. The study has been done in the year 2005 at Biology Laboratory the University of Papua Manokwari. The purpose of the research is to find out the kind of pathogenic fungus who cause disease of leaf blight and shaped-rotten to the Aristolochia plant. These activities are the first step to control and to overcome the blight leaf and shaped rotten disease at Aristolochia plants from pathogenic fungus. The result showed that Fusarium oxsisporum f. is a pathogenic fungus which cause leaf blight and shaped-rotten on four kind of Aristolochia plant at Minyambou. Fusarium oxsisforum f. will cause epidemic disease to all Aristolochia plant in the Arfak Mountain if immediately tackling</em>.<em></em></p>

The first finding of pythium root rot and leaf blight of elephant foot yam (Amorphophallus paeonifolius) in India

Elephant foot yam Amorphophallus paeonifolius , formerly known as A. campanulatus , produces an edible corm and is widely cultivated from West Bengal to Tamil Nadu, India. It is an example of a crop species that is indigenous to this region and has been included in the National Germplasm Evaluation Programme for tuber crop improvement. This important crop has recently suffered from a root rot and leaf blight disease. Symptoms of affected plants ranged from chlorosis, stunting to a complete blight as the disease progressed. Necrotic root symptoms began at the tip, but progressed quickly eventually killing the whole root. The cortex of severely affected roots could be easily sloughed off, leaving only parts of the vascular system intact. Samples of affected plants from production fields and an experimental farm (All India Coordinated Research Project on Tuber Crops in Nadia district, West Bengal) were collected. The pathogen was isolated by plating affected tissues on amended V8 agar (Guha Roy et al ., 2006). Resultant isolates were identified using morphological characters, DNA fingerprinting and sequencing. Sporangia were ovoid to globose, papillate, caducous and nonproliferating (41·46 μ m ± 2·9 × 37·64 μ m ± 2·0). Isolates were homothallic. Oogonia were spherical, smooth walled with elongate diclinous antheridia and aplerotic oospores (39·16 μ m ± 2·26 diameter). Hyphal swellings were absent. Based on the above morphological features and ITS sequencing (GenBank Acc. No. EF455802), the organism was identified as Pythium helicoides . Its SSCP (single stranded conformational polymorphism) pattern was also typical of P. helicoides (Kong et al ., 2004). Pathogenicity was confirmed by wound-inoculating stem bases of 3-month old healthy plants of A. paeonifolius with a 9-mm cork borer and placing 7-mm mycelial discs of 5-day old P. helicoidstest cultures in the holes. Plants were maintained at approximately 30 ± 1 ° C and assessed 15 days post inoculation. Pythium helicoides was successfully re-isolated, thus completing Koch’s postulates. Control plants inoculated with agar alone remained symptomless. This is the first report of P. helicoides affecting A. paeonifolius in India and worldwide. One isolate was deposited in the World Phytophthora Collection and Virginia Polytechnic Institute and State University, USA, under accession numbers P10973 and 33B2, respectively.

Prevalence and aetiology of Phytophthora foot rot of black pepper in Vietnam

Black pepper is a high value export crop in Vietnam. The production of black pepper, however, is reduced remarkably by Phytophthora foot rot disease. Although the disease was first reported in 1952, the identity of the causal organism has never been conclusively determined. Hence, the aim of this study was to identify the causal agent associated with Phytophthora foot rot epidemics in black pepper. A national survey of the disease and collection of samples were conducted in four major black pepper growing provinces. Phytophthora isolates obtained from the diseased roots, collars and leaves as well as the root-zone soil were identified by morphological characteristics and verified by ITS-RFLP analysis. Phytophthora capsici was determined as the main pathogen causing Phytophthora foot rot of black pepper in Vietnam based on disease symptoms, morphological characteristics, pathogenicity and ITS-RFLP analysis.

Photocatalytic disinfection of phytopathogenic bacteria by dye-sensitized TiO 2 thin film activated by visible light

Synthetic pesticides have been used to control plant diseases or pests for a long time. The public has been affected by many problems such as environmental pollution and health issues from synthetic pesticide use in agriculture. It has consequently become necessary to develop alternative methods for the control of plant diseases. The TiO 2 photocatalyst technique has potential for agricultural application because it will not form dangerous compounds. However, UV is only about 3% of the light existing in the solar spectrum. This limits TiO 2 photocatalytic disinfection application under visible light irradiation. Our current research emphasizes the improvement of TiO 2 thin film photocatalytic efficiency under visible light ( λ > 400 nm) by doping a novel photosensitive dye (5, 10, 15, 20-tetraphenyl-21 H, 23 H-porphine nickel, TPPN) using the sol–gel method. These results showed that the TiO 2 thin film doped with 200 μM of TPPN had high indigo dye photodegrading efficiency. The inhibition rates of TiO 2/TPPN thin film illuminated by visible light against phytopathogenic bacteria including Enterobacter cloacae SM1, Erwinia carotovora subsp. carotovora 3 and E. carotovora subsp. carotovora 7 which induced severe soft/basal rot disease in vegetable crops were all more than 90%. These evidence suggest that the TiO 2/TPPN thin film under visible light irradiation has the potential for direct application to plant protection in irrigation water systems.

Thermal control of some post-harvest rot pathogens of Irish potato (solanum tuberosum l.)

Thermal control effect on the incidence of some post-harvest rot pathogens of Solanum tuberosum (potato) was investigated in this study. Three cultivars of potato tuber whose local names are, Patiska, Mai Bawondoya and Nicola were used for the study. Five pathogenic fungi viz: Botryodiplodia theobromae, Fusarium redolens, Fusarium oxysporum, Penicillium sp. and Rhizopus oryzae associated with post harvest storage rot of root-tubers, were isolated from diseased potatoes. Among the three species of potatoes used in the study, Patiska was found most resistant followed by Mai Bawondoya, while Nicola was the least resistant. Increase in substrate (i.e. soluble starch or CMC) concentration enhanced a proportional increase in mycelial growth and in the amount of extracellular enzymes produced. Some of these test pathogens were found to produce cell wall degrading enzymes (i.e. amylase and cellulase). Preferential utilization of carbohydrate sources was established in this study based on the growth of test pathogens. Growth on potato broth medium was highest followed by growth on Cocoyam and Sweet potato broth media and least on Cassava broth medium. Growth of the test pathogens on carbohydrate sources was found at variant. The use of hot water treatment at different temperatures was found to significantly reduce post-harvest fungal populations on the surface of root-tubers. The efficacy of blanching in hot water at 60?C was significantly higher than that of blanching in hot water at other temperatures. The control method adopted in this study showed that the problems of potatoes? rot disease in storage (especially by the peasant farmers) can be eradicated by thermal treatments without reducing the quality of the Irish tuber.

EFFECTS OF CULTURAL MANAGEMENT ON THE FOOT AND ROOT DISEASE COMPLEX OF DURUM WHEAT

SUMMARY The effects of three tillage techniques (minimum tillage [chisel ploughing], and mouldboard ploughing to a depth of 25 and 50 cm) and four 2-year crop rotations (continuous wheat, wheat/barley, wheat/sugarbeet and wheat/fallow) on the foot and root disease complex of durum wheat were studied from 1999 to 2001 in an experimental field at the Bologna University farm. Brown foot rot (BFR) caused by Fusarium species and Bipolaris sorokiniana, and eyespot caused by Oculimacula spp. were the major components of the foot and root disease complex. Ploughing was significantly more effective than chiselling in controlling eyespot disease over the whole period of observation, whereas ploughing significantly reduced BFR only in 1999 when the incidence of the disease was the highest. Wheat/sugar-beet was generally less favourable for development of the foot and root disease complex than the other rotations tested. The effects of tillage techniques and crop rotations on disease were year-dependent. A more detailed analysis carried out in 2000 to evaluate the effect cultural practices on fungi associated with brown foot rot disease, indicated that F. culmorum was predominant with minimum tillage and scarce in ploughing, whereas B. sorokiniana was predominant in plots that were ploughed.

Physiological and Molecular Features of the Pathosystem Arabidopsis thaliana L.‐Sclerotinia sclerotiorum Libert

AbstractThe fungal pathogen Sclerotinia sclerotiorum Libert causes rot diseases on many crops worldwide and large economic losses occur frequently because of a lack of resistant varieties. The pathogenesis of S. sclerotiorum and the molecular basis of plant responses to the pathogen are poorly understood. In the present investigation, the process of S. sclerotiorum infection in Arabidopsis thaliana L., a plant that is highly susceptible to this fungus, was analysed. In addition, the defense activation in the host was investigated. A convenient inoculation method using millet grain was developed for S. sclerotiorum in Arabidopsis. The fungus rapidly infected the plants, probably through ball‐ or cushion‐like infection structures. Visible symptoms developed within 24 h and plants were killed 72 h after inoculation. Cellulase, the main enzyme that caused host tissues to rot, was secreted by S. sclerotiorum in a pH‐dependent manner. Oxalic acid, another pathogenic factor secreted by the fungus, induced necrotic lesions on the leaves. Infection with S. sclerotiorum strongly induced the production of the pathogenesis‐related (PR) proteins β‐1,3‐glucanase and chitinase in Arabidopsis. Furthermore, the PR gene PDF.1 was induced, but not PR1, indicating that the pathogen activated basal defense of jasmonic acid/ethylene dependence, which is consistent with its necrotrophic characteristics. This pathosystem for Arabidopsis‐S. sclerotiorum could provide an approach for the analysis of the interactions between S. sclerotiorum and other crops, thereby facilitating genetic manipulation techniques for controlling this pathogen.(Managing editor: Li‐Hui Zhao)

A New Report of Fruit Rot of Lemon Caused byCeratocystis radicicolafrom Iran

AbstractIn the year 2000, a fungus was isolated from rotting lemon (Citrus limon) fruit in the Kahnouj region, south‐eastern Iran and subsequently identified asCeratocystis radicicola(anamorph:Chalarasp.). A pathogenicity test was carried out to fulfil Koch's postulates. The pathogen could only enter the ripen lemon fruit and cause the rot disease through the wounds and cracks. The fungus was also pathogenic on fruit of other citrus species as well as date palm (Phoenix dactylifera). Symptom development was slow on fruits on the tree but accelerated after fruit harvest.

Complement of integrated fertilizer management and integrated pest management concepts to ameliorate faba bean growth and yield

Twenty-one microbial preparations recommended for controlling pathogenic fungal strains causing root rot and wilt diseases of faba bean were investigated for antibiosis against several symbiotic and associative diazotrophs adopting a modified agar-plate-inhibition-zone assay. Rhizobium and Bradyrhizobium exhibited a somewhat similar susceptibility to biocontrol agents while associative diazotrophs showed variable responses. Azotobacter, compared to others, was severely inhibited by such bio-candidates. The members of the biofertilizer formulation ‘Biofertan’ did bear mixed cultivation with the majority of biocontrol agents. Among those, Bacillus subtilis was deemed the pioneer. In pot experiments, almost all the antagonists significantly restricted the severity of root rot and wilt diseases besides modifying faba bean seedling stand and improving plant development. This was very obvious with shoot biomass increases of > 50%. Moreover, the bioagents successfully recovered the legume establishment, seriously injured due to pathogenic fungal infection. Simultaneous inoculation with Rhizobium and biocontrol agents provided more growth stimulation compared to either when introduced individually. Field-grown faba beans were inoculated with the diazotroph and representatives of biocontrol strains by two different methods, seed coating and over-head soil. Growth parameters determined were the highest when the legume plant was seed-coated by Rhizobium simultaneously over-head soil inoculated with the bacterial bioagents; this was reported with Bacillus subtilis and Pseudomonas aerugenosa. The significance of combined application of biofertilizer and bioagent to ensure cheap, clean and safe farm products is discussed.

Root Rot and Wilt of Kangaroo Paw (Anigozanthos manglesii) Caused by Pythium myriotylum (Drechs.) in Israel

A root rot and wilt disease of Anigozanthos manglesii (Kangaroo Paw) grown in greenhouses in Israel, for exporting as cut flowers to Europe, was characterized. Pythium myriotylum (Drechs.) and Rhizoctonia solani (Kuhn) were the prevalent pathogens in diseased plants collected from commercial greenhouses. Fusarium oxysporum, Fusarium spp. and Myrothecium sp. were also isolated, but P. myriotylum or R. solani were not detected in samples from symptomless plants in tissue cultures (Australian origin) or plants at different stages in the nursery; non-pathogenic F. oxysporum and Fusarium spp. were detected in several samples. In pathogenicity tests carried out in pots, plant mortality occurred 7 days after inoculation with P. myriotylum. In a field experiment carried out in methyl bromide-fumigated soil, the incidence of dead plants following inoculation with P. myriotylum alone was 22% 10 days after inoculation, increasing to 78% after an additional 25 days. The incidence of dead plants following inoculation with R. solani alone was only 5% and in plants inoculated simultaneously with both pathogens, disease incidence was 88% 35 days after inoculation. Mortality reached 90-100% in plants inoculated with P. myriotylum, either singly or combined with R. solani 60 days after inoculation, whereas in plants inoculated with R. solani it was 5%. The maximum mortality in plants inoculated with R. solani was 25%, 76 days after inoculation. These results clearly demonstrate that P. myriotylum was the dominant pathogen in the root rot and wilt of A. manglesii.