Biological Control of Brown Leaf Spot Disease Caused by Curvularia Lunata and Field Application Method on Rice Variety IR66 in Cambodia

Curvularia lunata was found to cause a serious rice brown leaf spot in Cambodia. This is the first report of brown leaf spot on rice in Cambodia. All isolates were tested for pathogenicity. Dual culture antagonistic tests showed that Chaetomium cupreum inhibited sporulation of C. lunata when compared to the control. In a pot experiment, C. cupreum significantly reduced the incidence of brown leaf spot caused by C. lunata. After application of a spore suspension of C. cupreum, Chaetomium-biofungicide and chemical fungicide (tebuconazole) to rice seedlings inoculated with C. lunata, the disease was reduced by 68.79 %, 75.80 % and 72.41 %, respectively. In a field trial, the chemical method gave the best results in all plant parameters, followed by the good agricultural practice (GAP) and organic methods. The chemical method gave the highest panicle/plant, panicle length, panicle weight, grain weight/plant which were different from the GAP and organic methods. The chemical method also gave the best results in filled grain panicle-1, unfilled grain panicle-1, grain weight plot-1, dry hay weight plot-1, biomass weight plot-1 and harvest index, and was significantly better than the GAP and organic methods

Application of a New Bio-Formulation of Chaetomium Cupreum for Biocontrol of Colletotrichum Gloeosporioides Causing Coffee Anthracnose on Arabica Variety in Laos

The anthracnose pathogen was isolated from coffee leave and bean symptoms. Morphological and molecular phylogenetic data confirmed the species as Colletotrichum gloeosporioides. The pathogenicity of the isolate was also confirmed by detached leaf method which inoculated the virulent isolate into coffee leaves. The crude extracts with hexane, ethyl acetate and methanol solvents from Chaetomium cupreum CC3003 resulted significantly inhibited C. gloeosporioides that the ED50 values of 13, 11 and 28 ppm, respectively. The bioactive substances of C. cupreum CC3003 expressed antifungal activity against C. gloeosporioides as can be seen in the abnormal appearance of spores. A powder bio-formulation of C. cupreum significantly resulted to reduce anthracnose disease of 54.77 %. The application of nano-rotiorinol, nano-trichotoxin and a spore suspension of C. cupreum reduced anthracnose incidence of 46.23, 42.71 and 18.59 %, respectively while the inoculated control had high anthracnose disease. The application of bio-formulation of C. cupreum in powder form, nano-rotiorinol, and nano-trichotoxin to reduce coffee anthracnose was reported for the first time in Lao PDR

A new species of bird’s nest fungi: characterisation of Cyathus subglobisporus sp. nov. based on morphological and molecular data

Recent collections of bird’s nest fungi (i.e. Crucibulum, Cyathus, Mycocalia, Nidula, and Nidularia species) in northern Thailand resulted in the discovery of a new species of Cyathus, herein described as C. subglobisporus. This species is distinct by a combination of ivory-coloured fruiting bodies covered with shaggy hairs, plications on the inner surface of the peridium and subglobose basidiospores. Phylogenetic analyses based on ITS and LSU ribosomal DNA sequences using neighbour-joining, maximum likelihood and weighted maximum parsimony support Cyathus subglobisporus as a distinct species and sister to a clade containing C. annulatus, C. renweii and C. stercoreus in the Striatum group

Evaluation of bio-agent formulations to control Fusarium wilt of tomato

The ED50 value of antagonistic substance from Chaetomium globosum N0802 extracted with hexane was 157 μg/ml. This gave the highest inhibition of conidial production of Fusarium oxysporum f. sp. lycopersici causing tomato wilt var Sida. Crude hexane from Chaetomium lucknowense CLT and crude methanol from Trichoderma harzianum PC01 gave ED50 values of 188 and 192 μg/ml. It clearly demonstrated that antagonistic substances from all tested fungi could be deformed and this could break the conidial cells. The bio-agent formulations namely N0802, CLT and PC01 gave significantly highest disease reduction of tomato wilt which were 44.68, 36.28 and 41.01%, respectively, followed by prochoraz (21.95%). All tested bio-agent formulations could significantly increase the yield of tomato when compared to prochoraz and inoculated control. It is concluded that C. globosum, C. lucknowense and T. harzianumKeywords: Fusarium oxysporum f. sp. lycopersici, Chaetomium globosum, Chaetomium lucknowense, Trichoderma harzianum, bio-agent formulationsAfrican Journal of Biotechnology Vol. 9(36), pp. 5836-5844, 6 September, 201

Application of biological fungicides to control citrus root rot under field condition in Cambodia

Pythium ultimum was recorded to be the first time to cause citrus root rot in Cambodia. The pathogen causes a serious damage almost everywhere planted to citrus in Battambang province. The pathogen infects the plants starting from seedlings which show yellow leaves, die back, stem rot, root rot and die. Mainly, the citrus trees express slowly decline from the second year and slowly die which starting from six to seven years old, even using the chemical fungicides. In laboratory test, the detached leave method has shown that only three days after inoculation of pathogen, the citrus leaves turning completely dark brown showing aggressive pathogen and proved for pathogenicity. In field trials, the chemical and biological fungicides namely Chaetomium and Trichoderma biological products were peroidically applied to four year old citrus trees in one year. All products were spayed above plants and to rhizosphere soil every month (metalaxyl-10g/20L of water in combination with chemical fertilizers, Chaetomium20g/20 L of water and Trichoderma-20g/20L of water in combination with biocompost). Result showed that all treated citrus trees recovered significantly within 3-4 months of applications. The new flashes of leaves and root were emerged and citrus tress recovered. It is proved that the biological products of Chaetomium and Trichoderma gave significantly disease control as equal as the chemical fungicide (metalyxyl) when compared to the non-treated control

Prediction of bioactive compounds activity against wood contaminant fungi using artificial neural networks

Biopesticides based on natural endophytic bacteria to control plant diseases are an ecological alternative to the chemical treatments. Bacillus species produce a wide variety of metabolites with biological activity like iturinic lipopeptides. This work addresses the production of biopesticides based on natural endophytic bacteria, isolated from Quercus suber. Artificial Neural Networks were used to maximize the percentage of inhibition triggered by antifungal activity of bioactive compounds produced by Bacillus amyloliquefaciens. The active compounds, produced in liquid cultures, inhibited the growth of fifteen fungi and exhibited a broader spectrum of antifungal activity against surface contaminant fungi, blue stain fungi and phytopathogenic fungi. A 19-7-6-1 neural network was selected to predict the percentage of inhibition produced by antifungal bioactive compounds. A good match among the observed and predicted values was obtained with the R2 values varying between 0.9965 – 0.9971 and 0.9974 – 0.9989 for training and test sets. The 19-7-6-1 neural network was used to establish the dilution rates that maximize the production of antifungal bioactive compounds, namely 0.25 h-1 for surface contaminant fungi, 0.45 h-1 for blue stain fungi and between 0.30 and 0.40 h-1 for phytopathogenic fungi. Artificial neural networks show great potential in the modelling and optimization of these bioprocesses.Les biopesticides à base de bactéries endophytes naturelles pour lutter contre les maladies des plantes constituent une alternative écologique aux traitements chimiques. Les espèces de Bacillus produisent une grande variété de métabolites biologiquement actifs tels que les lipopeptides ituriniques. Cette étude porte sur la production de biopesticides par des bactéries endophytes naturelles isolées du Quercus suber L. Des réseaux neuronaux artificiels ont été utilisés pour maximiser le pourcentage d’inhibition provoquée par l’activité antifongique des composés bioactifs produits par Bacillus amyloliquefaciens. Les composés actifs, produits en culture liquide, ont inhibé la croissance de 15 champignons et avaient un spectre d’activé antifongique plus large contre les contaminants fongiques de surface, les champignons de bleuissement et les champignons phytopathogènes. Un réseau neuronal 19-7-6-1 a été choisi pour prédire le pourcentage d’inhibition produit par les composés bioactifs antifongiques. Une bonne concordance entre les valeurs observées et prédites a été obtenue; les valeurs de R2 variaient de 0,9965 a` 0,9971 et de 0,9974 a` 0,9989 pour les bases d’apprentissage et de test. Le réseau neuronal 19-7-6-1 a été utilisé pour établir les taux de dilution qui maximisent la production des composés bioactifs antifongiques, nommément 0,25 h−1 pour les contaminants fongiques de surface, 0,45 h−1 pour les champignons de bleuissement et entre 0,30 et 0,40 h−1 pour les champignons phytopathogènes. Les réseaux neuronaux artificiels ont un potentiel élevé pour modéliser et optimiser ces processus biologiques

Effect of different factors on sporulation of Colletotrichum coffeanum

Abstract The effect of different factors on sporulation of Colletotrichum coffeanum was investigated. Result showed that V8 and PDA media were suitable for the growth of C. coffeanmum. On the contrary, the content of the media gave a significant impact on sporulation. The media content increased then it would greatly increase the sporulation. 12 h light/dark photoperiod (12:12 L:D; 10000 lux, fluorescent lamp) was the most suitable light condition for C. coffeanmum sporulation, compared with constant darkness (continuous darkness; CD) and constant illumination (continuous light; CL; 10000 lux, fluorescent lamp). Moreover, the growth rate in the 28 th day showed the fastest growing culture. It is concluded 10 ml PDA medium and incubated 28 days under natural light conditions was the best time of sporulation