Basal Rot Research Articles

Basal glume rot of wheat

Basal glume rot of wheat

Management of Fusarium Basal Rot of Onion caused by Fusarium oxysporum f.sp. cepae through Desert Plants Extracts

Management of Fusarium Basal Rot of Onion caused by Fusarium oxysporum f.sp. cepae through Desert Plants Extracts

In-vitro assessment for the control of Fusarium species using a lactic acid bacterium isolated from yellow pitahaya (Selenicereus megalanthus (K. Schum. Ex Vaupel Moran))

The fungistatic activity of a lactic acid bacterium, which had been isolated from yellow pitahaya cultures, against fungi associated with basal rot (Fusarium oxysporum and Fusarium fujikuroi) was measured in the present study. Its activity was assessed in three fractions: fermented (S1), metabolic products (S2), and biomass (S3), using two fermentation substrates: Man Rogosa Sharpe agar (MRS) and potato dextrose agar (PDA). The bacterium was molecularly identified as Lactobacillus plantarum. S3 reduced F. fujikuroi growth by 100% over 48 h of fermentation, which occurred during the stationary phase of bacterial growth. The three fractions’ fungistatic activity against F. fujikuroi depended on the substrate employed. The fermentation kinetic parameters for L. plantarum indicated that its specific growth rate was 0.46 h–1, with 93.63% substrate consumption, 0.045 kg kg–1 cell yield, and 0.54 kg kg–1 product yield. The kinetic parameters calculated will allow for bacteria production scaling. These in-vitro trials reveal L. plantarum’s possible application as a biocontrol agent for diseases associated with Fusarium. However, further ex-vivo and in-vivo researches are required to demonstrate its behavior in crops.

Genetic resistance to fusariosis and base rot in interspecific F1 progenies of passion fruit (Passiflora spp.)

Fusariosis and base rot, caused by the fungi Fusarium oxysporum f. sp. passiflorae and F. solani, respectively, seriously damage the cultivation of sour passion fruit in Brazil. This work aims to obtain and evaluate F1 hybrids of Passiflora spp. wild plants resistant to fusariosis and base rot using genotypes of P. edulis (commercial species) and certify interspecific hybridizations using microsatellite markers. Hybridizations were performed using a P. edulis female parent and P. nitida and P. mucronata male parents for crosses aiming fusariosis resistance, and P. nitida, P. cincinnata and P. quadrangularis for hybridizations aiming tolerance to base rot. 35 microsatellite markers were used to confirm hybridization. The washed roots method was used for fusarium resistance tests and inoculation procedure with a mycelium disk fixed on a small wound on the plant stem for base rot. The interspecific hybridizations provided 49 potentially hybrid genotypes. Confirmation of hybridization by microsatellite marker was verified for 57% of the analyzed genotypes. The hybrids 115-1, 115-3, 115-4, 115-5, 115-6, 115-7, 115-9 and 128 are indicated as promising genotypes for a new stage of the breeding program. In the resistance evaluation of 13 F1 hybrids to F. oxysporum f. sp. passiflorae, the genotypes 142 and 143-2 were selected as the most resistant to continue the breeding program.

Biological control of onion basal rot disease using phosphate solubilising rhizobacteria

ABSTRACT Onion basal rot is the most destructive disease caused by Fusarium oxysporum f. sp. cepae (FOC) for onion growing regions of the world. To control this disease, biological control agents 287 phosphate solubilising bacteria (PSB) were isolated from 43 onion rhizosphere soil samples. The value on the phosphate solubilisation index (SI) of the PSB was calculated to be in the range of 1.2–5.5, and a quantitative estimation of P solubilisation was investigated in liquid medium and found to be in the range of 15.2–382.5 mg/l. Furthermore, all tested organisms solubilised rock phosphates (RP) by lowering the medium’s pH. These isolates were tested for their effect on the mycelial growth of FOC in dual cultures. Eight isolates were determined to inhibit mycelial growth of FOC at rates from 71.5 to 75.7%. For the pot experiments, 15 rhizobacteria (12 isolates highest P-solubilising and 3 isolates P-solubilising and effective antagonist) were selected through 287 PSB. In the pot experiments, onion seeds (sensitive and resistant) coated with PSB were sown in soil which was infected with FOC and RP. Seed treatment with the isolates was found to suppress disease severity in ratios varying from 10.9 to 77.8%. At the same time, these PSB isolates significantly reduced disease, similar in degree to a chemical fungicide (Antrachol) (p < 0.05). The results of the in vitro and in vivo research demonstrated that the isolated PSB are potential biological control agents and need to be further researched for the biochemical basis of their activity against FOC.

An Artificial Inoculation Method to Select Mature Onion Bulbs Resistant to Fusarium Basal Rot

Fusarium basal rot (FBR) of onion, which is caused by Fusarium oxysporum f.sp. cepae (Hanzawa) Snyder &amp; Hansen (FOC) results in a substantial loss of marketable bulbs worldwide. One of the main reasons for the lack of FBR-resistant short-day cultivars is the unreliable screening methods available for the mature bulb stage when significant economic damage occurs. The objective of this study was to develop an artificial inoculation method with better quantification of inoculum for an effective selection of FBR-resistant mature onion bulbs. Mature bulbs of seven New Mexican short-day onion cultivars, along with susceptible and tolerant controls, were selected and evaluated for FBR resistance using mycelial and conidial inoculation methods, respectively. Transversely cut basal plates of mature bulbs were inoculated artificially with mycelia or conidia (12 × 105 spores/mL in 2014 and 3 × 105 spores/mL in 2015 embedded in potato dextrose agar plug) of a virulent FOC isolate ‘CSC-515’. Mature bulb evaluation using a visual rating scale (1 = no disease; 9 = &gt;70% basal plate infected) revealed a high degree of FBR severity and incidence irrespective of the genetic background of the cultivars, minimizing the chance of disease escape, which is a significant problem in field inoculation. An attempt to inoculate intact basal plates postharvest resulted in minimal disease development, suggesting that mechanical resistance was conferred by the dry outer layer of the basal plate. The high selection pressure conferred by the conidial inoculation method developed in this study can effectively screen FBR-resistant onion bulbs to replace an unreliable field screening. Concentrations of the conidia lower than 3 × 105 spores/mL are recommended to detect subtle genetic differences in FBR resistance among the onion cultivars and their selected population.

Epidemiological studies on base rot disease of Aloe vera caused by Fusarium oxysporum

Epidemiological studies on base rot disease of Aloe vera caused by Fusarium oxysporum

First report of basal rot of dragon fruit caused by Fusarium oxysporum in Bangladesh.

Dragon fruit (Hylocereus polyrhizus) is a high value newly introduced fruit crop in Bangladesh. It has drawn considerable public attention due to its appealing flesh color, sweet taste and fruit qualities. Recently, basal rot of dragon fruit plants was observed in several farmer's fields, nurseries and in the research field of Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU) where about 10-15% of plants were infected in each location. Initially, the symptoms appeared in the basal part near the soil as brown lesions which gradually extended to the upper stem and finally becoming soft and watery (Figure 1a). Infected plants were collected from Kapasia of Gazipur district (Latitude 24.266 and Longitude 90.633) to isolate the causal organism. Isolations were carried out following the procedure reported by Briste et al. (2019). Briefly, infected plant parts were surface sterilized in 2% NaOCl for 1 min followed by 70% ethanol for 5 min and rinsed 3 times with sterile double distilled water. A large piece of a surface sterilized plant was cut into small pieces (2 mm × 2 mm) from the margin of the necrotic lesion and placed on half strength potato dextrose agar (PDA) and incubated for 7 days at 25 °C. The BTFD1 and BTFD4 isolates were purified from single spores resulting in white colonies with a growth rate of 1cm/day on PDA (Figure 1b). Colonies produced single celled microconidia from unbranched, short monophialidic conidiophores and septate macroconidia as well as chlamydospores in PDA which is consistent with Fusarium oxysporum (Figure 1c). To confirm the identity of the isolates, the internal transcribed spacer (ITS1, 5.8S rRNA and ITS2) and translation elongation factor-1alpha (EF-1α) were amplified using primers ITS-1/ ITS-4 and EF1-728F/ EF1-986R, respectively (Surovy et al. 2018). The ITS sequences of the isolates BTFD1 and BTFD4 (GenBank accession # MN727096 and MN727095, respectively) showed 100% similarity with the sequence from F. oxysporum strain JJF2 (MN626452). Sequence identity for EF-1α (GenBank accession # MN752123 and MN752124, respectively) was 100% with the sequence from F. oxysporum strain CAV041_EO (MK783088). The isolates (BTFD1 and BTFD4) were identified as F. oxysporum based on the aligned sequences of ITS and EF-1α, molecular phylogenetic analyses by maximum likelihood tree (Figure 2a) and maximum parsimony tree methods (Figure 2b). The isolates were stored at 4°C on dried filter paper as well as in an ultra-low temperature freezer (-80°C) at IBGE, BSMRAU, Bangladesh and are available on request. To ensure pathogenicity, isolate BTFD1 was grown on PDA, incubated at 25°C for 7 days and 250 ml conidial suspension (with 1 × 105 conidia/ml) was prepared. Twelve,three-month-old healthy dragon fruit plants were inoculated. Pathogenicity tests were carried out in two sets using three replications in each set. In one set, only the basal part of the plants was dipped into the conidial suspension and in another set the whole plant was dipped into the conidial suspension for two hours. Sterile distilled water was also used in another set of plants as a control. The inoculated plants were placed on wet tissue in a plastic box (31cm × 24cm × 8cm) covered and incubated at 25°C. After 10 days, all inoculated plants in both sets developed rot symptoms similar to those observed in the field, while the control plants remained healthy (Figure 1d). The pathogen was successfully re-isolated from the inoculated symptomatic parts on half strength PDA medium and had morphology as characterized before, thus fulfilling Koch's postulates. This disease has been reported in Argentina and Malaysia (Wright et al. 2007; Hafifi et al. 2019). To the bet of our knowledge, this is the first report of Fusarium basal rot of dragon fruit in Bangladesh caused by F. oxysporum.

Beneficial Effects of Arbuscular Mycorrhizal Fungi and Trichoderma on Diseased Shallot

Purple blotch and fusarium basal rot are important shallot diseases which have caused significant yield loss. An alternative control method for these diseases is the use of biocontrol agents, such as arbuscular mycorrhizal fungi (AMF) and Trichoderma. The objectives of this study were to determine the effects of AMF and Trichoderma sp. on shallot growth and disease suppression. The experiment was set as a Complete Randomized Block Design with three treatments and three replications. The treatments were AMF, Trichoderma sp., and control. Each treatment was applied to a row and 15 shallot plants were taken as samples for observation. Disease severity of purple blotch and fusarium basal rot, plant height, number of leaves and shallot resistances to Fusarium solani were observed during this study. Results demonstrated that at seven weeks after planting, the application of AMF and Trichoderma sp. tended to suppress fusarium basal rot to 0.89% and 1.78% respectively, but only the application of AMF that suppressed purple blotch disease to 0.44%. The application of AMF and Trichoderma sp. also tended to increase plant height, number of leaves, leaf fresh weight and dry weight, root length, and bulb weight. In addition, AMF and Trichoderma sp. application increased shallot resistances against Fusarium solani.

Breeding onion for resistance to Fusarium basal rot: comparison of field selection and artificial inoculation

Fusarium basal rot (FBR) is one of the main onion diseases in Argentina. The Onion Breeding National Program, held at INTA Experimental Station in La Consulta, Argentina, has developed onion breeding lines with increased resistance to FBR through a selection scheme performed under field conditions. The aim of the present work was to evaluate the achieved response to selection in the FBR resistance trait, comparing two strategies: selection under field environment and artificial inoculations performed in controlled conditions. Seeds of the breeding line 17-1289 (P0) were inoculated with Fusarium oxysporum f.sp. cepae (isolate FOC LJC10081), one seed per cap. After 15 days 162 surviving plants were treated with fungicide and transplanted. The resulting bulbs were planted and recombined avoiding contamination with foreign pollinators. The obtained seeds were labelled as PCC (Progeny generated under Controlled Conditions). Another portion of P0 seeds was grown under field conditions in a FBR-conductive soil. The best bulbs were selected at harvest based on their FBR resistance score, root system quality and agronomic features. These bulbs later produced seeds by recombination in isolation and were labelled as PFC (Progeny generated under Field Conditions). The P0 population and the PCC-PFC progenies were then compared through a standardized test for determination of FBR resistance, using two inoculum concentrations in the substrate. The incidence of FBR was significantly reduced in PCC at high inoculum concentrations, in comparison to the original population P0. Disease progression was delayed and lower rates were achieved in PCC. The described lab selection technique may constitute an interesting and useful tool to select materials that carry genetic resistance and contribute to an integrative approach, complemented with selection under field conditions, in onion breeding programs for FBR resistance.

Etiology and control of Gypsophila paniculata L. stem base rot in the Caraz Valley, Ancash

Gypsophila is an ornamental plant whose flowers are economically important, which is cultivated in the Callejon de Huaylas valley-Ancash. Recently, cultivated Gypsophila fields have shown diseased plants characterized by stem base rot, which has been followed by a reduction in vigor and the collapse and death of plants. Therefore, the objectives of this research were to describe the symptomatology of the disease, identify the causative agent of the disease, and prove how effective fungicides and biological control agents (BCA) are in controlling the disease using in vitro and field experiments. To isolate the pathogen, symptomatic plant tissue samples were washed, cut into small pieces, disinfected in 1% sodium hypochlorite solution for 1 min, rinsed twice with sterilized water, and air-dried on paper towels. The samples were seeded on Petri dishes containing potato dextrose agar media and incubated at 25 °C. A pathogenicity test was conducted in healthy Gypsophila seedlings, which were grown in a sterilized substrate, using mechanical inoculation on the stem base and agar disks colonized by the pathogen-mycelium. Then the pathogen was reisolated from symptomatic inoculated Gypsophila seedlings. The “poisoned medium” technique was used to conduct the in vitro fungicide test, while the “dual method” was used to conduct the bio controller’s test. The results of the pathogenicity test and in vitro and field experiments showed that Rhizoctonia solani is the causative agent of the stem base Gypsophila disease, and at both assayed doses, the fungicides Rovral, Benopoint, Parachupadera, Vitavax, and Homai completely inhibited the mycelial growth of R. solani. Moreover, the BCAs Trichoderma harzianum and T. viride showed higher in vitro growth rates than R. solani and completely colonized the pathogen-mycelium. Under field conditions, the incidence of the disease in field plots treated with T. harzianum was 12.5% lower than in the control treatment, which showed 51.28% incidence of the disease. In addition, Gypsophila plants harvested from plots treated with T. harzianum exhibited higher numbers of flower stalks per plant and a higher fresh weight compared to the control treatment.

Comparing Efficiencies of Two Selection Approaches for Improving Fusarium Basal Rot Resistance in Short-Day Onion after a Single Cycle of Selection

The development of Fusarium Basal Rot (FBR)-resistant onion cultivars through field and seedling screening approaches faces tremendous challenges due to non-uniform distribution of the disease pathogen and possible multiple mechanisms of host–plant resistance. This study compared the efficiencies of these two methods for increasing FBR resistance of short-day onion after a single selection cycle. Asymptomatic plants or bulbs of seven onion cultivars were selected using a seedling screen performed in a growth chamber or a field screening of mature bulbs. Original and selected populations were evaluated for their responses to FBR stress thereafter employing the same two methods used for screening. The field screening of mature bulbs was found unreliable in both selection and evaluation, likely due to a non-random distribution of the FBR pathogen and variable environmental factors present in the field. The seedling screening successfully increased FBR resistance in the selected cultivar populations revealed by a seedling evaluation. From the results, it is recommended to use a consistent method for both screening and evaluation to make the most selection progress.

Brevibacillus fortis NRS-1210 produces edeines that inhibit the in vitro growth of conidia and chlamydospores of the onion pathogen Fusarium oxysporum f. sp. cepae.

Onions can be damaged by Fusarium basal rot caused by the soilborne fungus Fusarium oxysporum f. sp. cepae (FOC). Control of this pathogen is challenging since there is limited genetic resistance in onion. The identification of molecules that inhibit this pathogen is needed. Antagonism screening showed Brevibacillus fortis NRS-1210 secreted antifungal compounds into growth medium. The spent growth medium, diluted 1:1, inhibited growth of FOC conidia after seven hours and killed 67-91% of conidia after 11 h. The spent medium also inhibited growth of propagules from F. graminearum, F. proliferatum, F. verticillioides and Galactomyces citri-aurantii. Full strength spent growth medium did not effectively kill FOC conidia and chlamydospores inoculated into a sand cornmeal mixture. In silico analysis of the B. fortis NRS-1210 genome indicated the biosynthetic clusters of several antibiotics. Fractionation of spent medium followed by reverse-phase liquid chromatography with tandem mass spectrometry analysis found that fractions with the most antifungal activity contained a combination of edeines A, B and F and no other recognized antibiotics. 1H NMR signals of the active fraction corresponded to edeine, a pentapeptide with broad spectrum antimicrobial activity which blocks translation in both prokaryotes and eukaryotes. Comparative genomics of Brevibacillus genomes shows edeine producers form a clade which consists of: Brevibacillus brevis, Brevibacillus formosus, 'Brevibacillus antibioticus', Brevibacillus schisleri, Brevibacillus fortis, and Brevibacillus porteri. This observation suggests edeine played an important role in the evolution and speciation of the Brevibacillus genus.

Isolation and Identification of Fusarium spp., the Causal Agents of Onion (Allium cepa) Basal Rot in Northeastern Israel.

Over the past decade, there have been accumulating reports from farmers and field extension personnel on the increasing incidence and spread of onion (Allium cepa) bulb basal rot in northern Israel. The disease is caused mainly by Fusarium species. Rotting onion bulbs were sampled from fields in the Golan Heights in northeastern Israel during the summers of 2017 and 2018. Tissue from the sampled onion bulbs was used for the isolation and identification of the infecting fungal species using colony and microscopic morphology characterization. Final confirmation of the pathogens was performed with PCR amplification and sequencing using fungi-specific and Fusarium species-specific primers. Four Fusarium spp. isolates were identified in onion bulbs samples collected from the contaminated field: F. proliferatum, F. oxysporum f. sp. cepae, and two species less familiar as causative agents of this disease, F. acutatum and F. anthophilium. Phylogenetic analysis revealed that these species subdivided into two populations, a northern group isolated from white (Riverside cv.) onion bulbs, and a southern group isolated from red (565/505 cv.) bulbs. Pathogenicity tests conducted with seedlings and bulbs under moist conditions proved that all species could cause the disease symptoms, but with different degrees of virulence. Inoculating seeds with spore suspensions of the four species, in vitro, significantly reduced seedlings’ germination rate, hypocotyl elongation, and fresh biomass. Mature onion bulbs infected with the fungal isolates produced typical rot symptoms 14 days post-inoculation, and the fungus from each infected bulb was re-isolated and identified to satisfy Koch’s postulates. The onion bulb assay also reflected the degree of sensitivity of different onion cultivars to the disease. This work is the first confirmed report of the direct and primary cause of Fusarium onion basal rot disease in northeastern Israel. These findings are a necessary step towards uncovering the mycoflora of the diseased onion plants and developing a preventive program that would reduce the disease damage.

Clinical significane of two-dimensional speckle tracking technique in the evaluation of diagnosis and prognosis of heart failure with left ventricular ejection fraction preservation

Objective To observe the clinical effect of two-dimensional speckle tracking technique in diagnosis and prognosis evaluation of heart failure with left ventricular ejection fraction preservation. Methods A total of 64 heart failure patients with reduced left ventricular ejection fraction (HFNEF) and 64 healthy volunteers in the Integrated Traditional Chinese and Western Medicine Hospital of Wenzhou were selected from July 2016 to July 2018.Conventional echocardiography and two-dimensional speckle tracking were performed in all subjects.The hemodynamic parameters and strain parameters of two-dimensional speckle tracking were recorded.The differences of conventional echocardiographic parameters and two-dimensional speckle tracking strain parameters in different subjects were analyzed. Results The E/A (0.79±0.24) and E/E' value (18.93±3.41) in HFNEF patients had statistically significant differences compared with healthy subjects [(1.28±0.35) and (6.84±1.37)] (t=9.507, 23.294; P=0.000, 0.000). There were no statistically significant differences in HR, LAD, LVD, LVSD, LVPWD, LVEF and LVFS between HFNEF patients [(71.37±5.93)times/min, (35.32±4.37)mm, (47.13±5.01)mm, (9.24±1.76)mm, (9.35±1.82)mm, (63.98±5.37)%, (35.49±4.46)%] and healthy subjects [(70.14±5.28)times/min, (37.64±4.69)mm, (49.26±5.54)mm, (9.39±1.82)mm, (9.48±1.90)mm, (66.35±5.41)%, (34.02±4.17)%] (t=0.384-1.628; P=0.102-0.564). In HFNEF patients, the anterior septum, anterior wall, posterior wall, inferior wall and posterior wall of apical segment of left ventricle, the inferior wall and posterior wall of papillary muscle and the posterior wall, inferior wall and posterior wall of basal segment, SRs and ROT of left ventricle were significantly lower than those of healthy subjects, while GLS (-13.52±4.18) and GCS (-10.43±3.85) of left ventricle in HFNEF patients were significantly higher than those of healthy subjects [(-19.89±4.61) and (-15.67±4.24)] (t=8.947~14.063; P=0.000-0.000<0.05). After treatment, the clinical symptoms of HFNEF patients improved significantly in the whole apical segment of left ventricle, inferior and posterior wall of papillary muscle segment, posterior lateral wall, inferior wall, posterior wall SRs and left ventricular GLS, GCS and ROT (t=7.258-13.193; P=0.000-0.000<0.05). Two-dimensional strain GLS and GC values in HFNEF patients were negatively correlated with E/A values and positively correlated with E/E' value (r=-0.817, -0.763; P=0.004, 0.012<0.05), while two-dimensional strain ROT results were positively correlated with E/A values and negatively correlated with E/E' values (r=-0.805, -0.759; P=0.006, 0.014<0.05). Conclusion Left ventricular systolic function damage has occurred in HFNEF patients.Two-dimensional speckle tracking technique is highly sensitive to the changes of myocardial systolic function for HFNEF patients.It has high clinical value in the diagnosis and prognosis evaluation of HFNEF.Relevant clinical workers should pay attention to it. Key words: Two-dimensional speckle tracking technique; Echocardiography; Heart failure with left ventricular ejection fraction preservation; Relevance; Left ventricle; Myocardial dysfunction; Diagnosis; Prognostic evaluation

Evaluation of different carbon sources for anaerobic soil disinfestation against Rhizoctonia solani on lettuce in controlled production systems

Effects of anaerobic soil disinfestation (ASD) on Rhizoctonia solani basal rot of lettuce were assessed considering: two soil types; different C-sources; different temperature regimes; two treatment durations; and two lettuce crop cycles, in the presence of a high disease incidence from artificial infestation with the pathogen. C-source, temperature, and incubation period, and their interaction, affected the efficacy of the ASD treatment for the lettuce–R. solani pathosystem, with differences depending on the soil type. Brassica carinata pellets, used as a C-source, reduced incidence of Rhizoctonia basal rot in the first crop cycle by 50 to 69% in a peat soil after 3 weeks of treatment at 21°C, and by 52 to 60% after 3 weeks of treatment at 26 or 31°C, compared to the inoculated and untreated experimental controls without anaerobic conditions. The best disease reduction was provided by B. carinata pellets applied, under anaerobic conditions, to peat soil (79% efficacy) and a sandy loam soil (100% efficacy) kept at 31°C for 6 weeks. Generally, ASD based on B. carinata pellets provided greater disease reduction in the first crop cycle than the second, with the only exception being for results achieved in both soils incubated for 6 weeks at 21, 26 and 31°C. Wild rocket used as a C-source provided the greatest disease reduction (78–83%) on plants grown in peat soil at the first crop cycle after 6 weeks of the ASD treatment at 31°C, while wild rocket provided disease reduction of 29 and 50% when mixed with the sandy-loam soil under the same conditions for 6 weeks. The efficacy of the ASD treatment with compost was improved in the second crop cycle, compared to the first, resulting in the greatest disease reduction (52 and 66% efficacy) reached in the sandy-loam soil incubated for 3 weeks at 21°C, and 63% efficacy in peat soil previously treated for 6 weeks at 26 and 31°C. However, slight reductions in lettuce plant development was generally evident in the first crop cycle, which could be due to differences in efficacy of the tested ASD treatments and to phytotoxicity. The greatest yield from sandy loam soil was obtained for the B. carinata pellets and wild rocket at 26 and 31°C in the second cultivation cycle. Partial efficacy of ASD does not justify the adoption of this method against R. solani on lettuce under intensive crop systems. However, ASD based on Brassicaceae and compost as carbon source applied in a sandy-loam soil may be valuable for reducing R. solani incidence, at lower temperatures than those required for soil solarisation or biosolarisation.

Characterization of Fusarium spp. associated with the basal rot of the green onion

Characterization of Fusarium spp. associated with the basal rot of the green onion

Has compost with biochar added during the process added value over biochar or compost to increase disease suppression?

Adding biochar at the onset of composting has proven to be beneficial for this process, and when added to the soil, this biochar-blended (BB) compost has outperformed biochar on soil quality but had a similar effect as the compost. Because soil quality gets more and more attention as an important tool for soil health, pot trials were conducted to evaluate the effect of compost and biochar alone, and biochar-blended (BB) compost on disease suppression. In addition, it was investigated whether the disease suppression was associated with changes in soil quality (chemical, physical and biological soil properties). The two selected bio-assays were Rhizoctoniasolani (basal rot) on lettuce and potato cyst nematodes (PCN) on potato. Both compost and BB compost released mineral N and thus increased lettuce and potato yield but biochar did not. None of the amendments affected the susceptibly of lettuce leaves to basal rot. Compost suppressed PCN while biochar had no effect on PCN reproduction. Moreover, BB compost reduced the suppressing effect of compost. We suggest that the inhibitory effect of biochar blended in compost might be attributed to the fungal biomass which was not increased in the BB compost-amended soil compared to compost-amended soil, and/or the absorbance of suppressive compounds by the high surface area of biochar. Interestingly, all three amendments reduced the water evaporation from the soil surface, which can have important implications for drought stress of plants.

Electronic nose for early detection of basal stem rot caused by Ganoderma in oil palm

The successful control of basal rot disease (BSR) determined by early detection of infection because when the symptoms already appear, generally plants are difficult to save. The earlier the Ganoderma infection is known, the easier the control will be and the losses can be minimized. Therefore, early detection of Ganoderma infection is very necessary, which in this study was carried out by detecting volatile compounds using electronic nose (E-nose). E-nose detection has been carried out to analyze the compounds formed in pure Ganoderma culture. Detection of plants in the field carried out at 4 levels of infection, i.e. healthy, early, moderate and severe infection. The results concluded that Ganoderma mycelium when compared with other fungi (Trichoderma, Aspergillus and Omphalina) showed significant differences when analyzed using an unsupervised PCA chemometric system. The E-nose data processed using machine learning Support Vector Machine (SVM) was able to distinguish the aroma between Ganoderma boninense CSB, G. boninense ‘Rejosari’, and G. lucidum with an accuracy rate of 99.64%. E nose was able to differentiate with high accuracy (90.95%) of each infection level even though there was still a slice between in root sample.

Ability of Trichoderma harzianum in carbon fiber and silica nano particles formulation to control Fusarium oxysporum in vitro

Basal rot disease caused by Fusarium oxysporum f. sp. cepae is one of the major diseases that cause yield loss on shallot. Utilization of biocontrol agents can be applied as an environmentally safe control method. The antagonistic microorganism that has the potency to control fusarial diseases is Trichoderma harzianum. A carrier is required in preparing a formulation of this antagonistic fungus as a biocontrol delivery system (BDS). Carbon fiber was proven suitable as a carrier of some antagonistic bacteria. A formulation can also be supplemented with plant micronutrient. Addition of silica nano particles (Si NPs.) in the formulation did not reduce the viability of the antagonistic bacteria. An experiment was carried out to determine the ability of T. harzianum in the formulation with carbon fiber and Si NPs. to suppress the in-vitro growth of F. oxysporum. The experiment was arranged in the completely randomized design with 5 treatments and 5 replications. The treatments were challenging F. oxysporum by T. harzianum in different composition of formulation on potato dextrose agar. The compositions consisted of T. harzianum + 0.5% Si NPs., T. harzianum + 1% Si NPs., T. harzianum + 0.5% Si NPs. + 5% carbon fiber, T. harzianum + 1% Si NPs. + 5% carbon fiber, and T. harzianum only (control). The results showed that each treatment with T. harzianum in the formulation of carbon fiber + various concentrations of Si NPs. was able to suppress the in vitro growth of F. oxysporum by 58.39-60.92%. The BDS with carbon fiber and Si Nps. did not significantly reduced the ability of T. harzianum to antagonize F. oxysporum. The control treatment of single T. harzianum caused the highest suppression on the growth of F. oxysporum, up to 60.93%..