Combined effect of generally regarded as safe (GRAS) compounds andTrichoderma harzianum on the control of postharvest diseases of rambutan

Botryodiplodia theobromae, Colletotrichum gloeosporioides andGliocephalotrichum microchlamydosporum are the causal fungi of the rambutan postharvest diseases stem-end rot, anthracnose and brown spot, respectively. Two different treatments of rambutan fruits(Nephelium lappaceum) against the three pathogens were compared: potassium metabisulphite (250 ppm) or cinnamaldehyde (30 ppm), each combined withTrichoderma harzianum (TrH 40). The application of TrH 40 and potassium metabisulphite effectively controlled the incidence and severity of the three postharvest diseases and maintained the overall quality and color of the fruit under low temperature storage at 13.5°C and 95% r.h. for 18 days. The greatest effect of this treatment was shown onG. microchlamydosporum. Cinnamaldehyde affected the growth and germination of TrH 40, whereas potassium metabisulphite did not. http://www.phytoparasitica.org posting Nov. 4, 2001.     

Effect of GRAS compounds on mycelial growth, pectic enzyme activity and disease severity of postharvest pathogens on rambutan (Nephelium lappaceum)

The GRAS compounds cinnamaldehyde (at 30 ppm), acetaldehyde (at 70 ppm), benzalde-hyde (at 50 ppm) and potassium metabisulphite (at 250 ppm) either completely inhibited or significantly reduced thein vitro mycelial growth ofGliocephalotrichum microchlamydosponim,Colletotrichum gloeosporioides andBotryodiplodia theobromae, the causative fungi of brown spot, anthracnose and stem end rot, respectively, of rambutan fruits,Nephelium lappaceum. The four compounds also significantly reduced the severity of all three diseases and the activity of pectic lyase and polygalacturonase enzymes secreted by the three fungi.     

Effect of ammonium carbonate and sodium bicarbonate on anthracnose of papaya

Colletotrichum gloeosporioides is the causal organism of anthracnose inCarica papaya L. (papaya, papaw). The effect of ammonium carbonate (3%) or sodium bicarbonate (2%) in aqueous solution or when incorporated into a wax formulation on anthracnose severity in inoculated or naturally infected fruits was examined. Both salts had significant effects, but that of ammonium carbonate was greater than that of sodium bicarbonate in controlling anthracnose. Ammonium carbonate (3%) incorporated into the wax formulation effectively reduced anthracnose incidence by 70% in naturally infected papaya and extended the storage life by maintaining the firmness, color and overall quality of the fruit in low temperature storage (13.5°C) and 95% r.h. for 21 days followed by 2 days under marketing conditions. The mode of action of ammonium carbonate on the control of anthroacnose appears to bevia complete inhibition of radial mycelial growth and conidia germination. http://www.phytoparasitica.org posting Aug. 14, 2002.     

Evaluation of screening methods against Corynespora leaf fall disease of rubber (Hevea brasiliensis)

Journal of Plant Diseases and Protection - Identification of resistant clones is a major strategy in the management of Corynespora leaf fall disease (CLFD) of rubber. Several methods to identify...     

A sensitive polymerase chain reaction based assay for the detection of Setaria digitata: the causative organism of cerebrospinal nematodiasis in goats, sheep and horses

A sensitive PCR assay for the detection of Setaria digitata has been developed. Two oligonucleotide primers (17 nt) were designed from a previously cloned and characterized tandemly arranged repetitive sequence of Setaria digitata. Using these primers, it was possible to amplify small quantities (100 fg) of S. digitata genomic DNA. A simple procedure, using proteinase K and non-ionic detergent NP 40, was followed to process the host blood samples and mosquitoes harbouring L3 larvae. The sensitivity of the polymerase chain reaction based assay surpasses the microscopic detection and the previously reported oligonucleotide based chemiluminescent detection of microfilariae in infected host blood samples and L3 larvae in mosquitoes.     

Control of postharvest diseases of rambutan using controlled atmosphere storage and potassium metabisulphite or<Emphasis Type="Italic">Trichoderma harzianum</Emphasis>

Botryodiplodia theobromae, Colletotrichum gloeosporioides andGliocephalotrichum microchlamydosporum are the causal fungi of three rambutan postharvest diseases, stemend rot, anthracnose and brown spot, respectively. Two different treatments of rambutan fruits to control the diseases were investigated: application of potassium metabisulphite (250 ppm) or culture filtrate ofTrichoderma harzianum (TrH 40) followed by controlled atmosphere storage (CA) at 13.5°C and 95% r.h. Potassium metabisulphite at 250 ppm under CA effectively controlled the incidence and severity of the three postharvest diseases and maintained the eating quality and color of the fruit for 21 days. The greatest effect of this treatment was on brown spot disease, caused byG. microchlamydosporum. Application of TrH 40 was less effective than potassium metabisuphite. http://www.phytoparasitica.org posting July 8, 2002.     

Spontaneous Extraskeletal Osteosarcoma in a Rabbit (Oryctolagus cuniculus): Histopathological and Immunohistochemical Findings

A spontaneously occurring subcutaneous mass in the left forelimb of a nine-year-old rabbit (Oryctolagus cuniculus) was examined histopathologically and immunohistochemically. Clinically, edema and hemorrhage were seen around the mass. No connection of the tumor mass to the appendicular skeleton was found. The tumor was arranged in a solid growth pattern and irregular bundles, and neoplastic cells were polygonal to spindle-shape. Osteoid (positive for osteocalcin) and multinucleated giant cells were diffusely or focally seen. Neoplastic cells were positive for vimentin, osterix and Ki-67, indicating the nature of osteoblasts with proliferating activity, but negative for α-smooth muscle actin, desmin or CD204. Based on these findings, a diagnosis of extraskeletal osteosarcoma was made, a very rare tumor both in laboratory and pet rabbits.     

Development of a formulation of Trichoderma asperellum to control black rot disease on pineapple caused by (Thielaviopsis paradoxa)

A local isolate of Trichoderma asperellum was tested for its antagonistic activity against Thielaviopsis paradoxa (telemorph = Ceratocyctis paradoxa). The highest antagonistic activity was achieved when the concentration of T. asperellum conidia was 1 × 10⁷ conidia/mL. The highest biomass and number of colony forming unit/mL of the T. asperellum peaked at 144 h after incubation in yeast waste residue medium. The minimum inhibition concentration value of the formulation was observed as 1% on growth of Th. paradoxa incubated at 28 ± 2 °C for 10 d. In the soil fungicide-screening test, the effect of concentrations 100-1600 μg/mL on mycelia growth was not significant (P < 0.05). Complete mycelial growth inhibition occurred at concentration above 52,600 μg/mL. Results of the fruit application tests clearly showed that all treated fruits were free of disease at the end of the incubation period. No significant differences (P > 0.05) in pH, total soluble solids and titratable acidity were observed between fruits treated with formulation of T. asperellum and the control formulation treated pineapples.     

Differentiation of Setaria digitata and Setaria labiatopapillosa using molecular markers

5S rRNA intergenic regions of Setaria digitata and Setaria labiatopapillosa were PCR amplified with primers designed from the 5S rRNA gene of Brugia malayi. The ladder-like banding patterns obtained for the amplifications were distinctly different for the two species. Four amplified products were cloned into the pBS vector and completely sequenced. DNA clones from two individual samples of S. digitata, Sd4 and Sd6, showed 97% sequence homology to each other. All sequenced clones showed the presence of the spliced leader (SL) RNA gene with a 22 nucleotide spliced leader sequence. The phylogenetic tree constructed using these data and the 5S rRNA intergenic regions of several other filarial nematodes showed the Setaria species sharing a branch with Dirofilaria. RAPD-PCR analyses identified 107 bands of which 86 were polymorphic (80%). A dendrogram constructed for S. digitata and S. labiatopapillosa separated the two species into two distinct clusters. The polymorphic loci identified by the RAPD-PCR analyses can be studied further to develop species-specific probes/PCR primers for the identification of each species.     

Antagonistic effect ofTrichoderma harzianum on postharvest pathogens of rambutan (Nephelium lappaceum)

Trichoderma harzianum (TrH 40) isolated from soil samples from rambutan orchards (Nephelium lappaceum) had antagonistic effects against three postharvest pathogens of rambutan:Botryodiplodia theobromae, Colletotrichum gloeosporioides andGliocephalotrichum microchlamydosporum, causative fungi of stem end rot, anthracnose and brown spot, respectively. The effects were due to both antibiosis and mycoparasitism.T. harzianum (TrH 40) treatment, while reducing the occurrence of the three postharvest diseases, also retained the overall quality and color of the fruits.