Infection of Chilli by Cercospora capsici

C. capsici was shown to be consistenlly associated with leaf spot of chilli, reducing appreciably the photosynthetic activity of infected plants leading to losses in yield. Incipient symptoms consisted of small, necrotic lesiom un the surface of the leaves, which later coalesced giving an irregular and blighted appearance with the production of abundant cOnidia, The pathogen sporulated abundantly at 20-30' but poorly at 10' C.At 40' C, no sporulation occurred. Sporulation on lesions was greatest near moisture! ,sporulation on lesions was greatest near moisture saturation but declined with decreasing water potential to -6 Mpa. The best temperature for germination was in the range of 20-30· C and declined with decreasing water potential. Pathogenicily tests and studie on the mode of infection of C, capsici on chilli leaves revealed that the fungus entered through the stomata, indicating that it was a primary invader

Antagonistic effect of Malaysian isolates of trichoderma harzianum and gliocladium virens on sclerotium rolfsii

Trichoderma harzianum and Gliocladium virens isolated from parasitized sclerotia were evaluated for their antagonistic potential against Sclerotium rolfsii. Based on the mechanisms ofantagonism in vitro, dual culture and colony degradation tests, hyphal interaction, antibiosis and parasitism of sclerotia, both antagonists were found to be effective against S. rolfsii. However, G. virens was more effective than T. harzianum in dual culture and colony degradation tests. Under SEM, both antagonists colonized, penetrated and sporulated inside the sclerotia of the test pathogen, suggesting parasitism of sclerotia could be the principal mechanism involved. T. harzianum and G. virens were comparable in their antibiosis activity. In addition, they can co-exist together and are synergistic in activity when tested simultaneously in dual culture

Penyakit Anthracnose pada eili Di Malaysia: Biologi Patogen dan Varietal Susceptibility

Studies on the biology of Colletotrichum capsici showed growth and sporulation were at maxima at 30°C and pH 5. Among the media used, Bean Pod Agar and Potato Dextrose Agar were more conducive for growth while Lima Bean Agar was most conducive for sporulation. Cultures receiving continuous normal light and normal light alternated with ultra violet gave better growth while those exposed to diurnal treatment gave better sporulation. Glasshouse trials showed that variety C10 was most susceptible to anthracnose when compared to the other varie ties tested. VarietY' C1 showed the highest tolerance level to anthracnose

Potential for biological control of sclerotium foot rot of chilli by trichoderma spp.

Air-dried preparations of Trichoderma harzianum and T. virens were evaluated for their survival and potential as biocontrol candidates against Sclerotium foot mt of chilli (Capsicum annuum, L) singly or as mixtures incorporated into organic fertilizers Amina, Avanti Green and Green Supergro as carriers. T. harzianum and T. virens incorporated singly into Amina and Avanti Green remained viable for 180 days but when incorporated into Green Supergro lost viability rapidly to zero after 30 days storage. The performance of the biocontrol candidates was also significant with Amina when tested in the artificially-inoculated soils. In the field, the incorporation of an organic carrier only improved initial establishment of the biocontrol candidates. The incidence of Sclerotium foot rot was significantly reduced with the reduction in the viable sclerotia of the pathogen and recovery of the biocontrol candidates in the chilli Thizosphere and mots was high. T. virens was a better candidate, giving 100 and 92.1 % control of Sclerotium foot rot in the artificially-inoculated and naturally - infested soils respectively

Effect of seed bacterization on plant growth response and induction of disease resistance in chilli

This study aimed to examine the induction of disease resistance, and growth response in chilli plants elicited by plant growth promoting endophytic bacteria [Pseudomonas aeruginosa (UPMP3), Burkholderia cepacia (UPMB3), and Serratia marcescens (UPMS3)]. Seed bacterization with UPMP3 and UPMB3 significantly increased peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) activities. This increase corresponded to greater reduction in pre- and post-emergence damping-off caused by Sclerotium rolfsii. UPMS3 alone or as mixture with UPMP3 and UPMB3 did not show any significant reduction in disease incidence. However, all the isolates tested did not inhibit the seed germination and seedling establishment in chilli

Comparative Morphology and characterization of colletotrichum isolates occurring on Cocoa in Malaysia

Isolation from cocoa leaves showing symptoms of shot-hole, blight or irregular leaf spot and from cherelles and pod rot yielded Colletotrichum gloeosporioides. No distinct differences in cultural and morphological characteristics were noted between the various isolates. The fungus was found to grow and sporulate well at 3()C. Cocoa LeafExtract Agar (CllA) was the best medium for mycelial growth while Potato Dextrose Agar appeared to favour sporulation. Both cocoa leaves and injured pods were liable to infection by C. gloeosporioides. Three week old cocoa seedlings and cherelles were noted as the most susceptible stages

Molecular characterization of Pseudomonas aeruginosa UPM P3 from oil palm rhizosphere

Problem statement: Pseudomonas aeruginosa has been used in agriculture as biological agents. It has shown substantial control of a variety of soil-borne plant pathogens including Macrophomina phaseolina, Botrytis cinerea, Rhizoctonia solani, Colletotrichum truncatum, Pythium, Fusarium and others. Species aggregate of Pseudomonas aeruginosa strain UPM P3 was shown to have potential as a biocontrol agent against Ganoderma boninense, the causal agent of Basal Stem Rot (BSR) of oil palm. However, P. aeruginosa is also an opportunistic pathogen. It typically infects the pulmonary tract, urinary tract, burns, wounds and also causes other blood infections. The objective of this study was to carry out DNA fingerprinting for strain differentiation to differentiate between pathogenic and non-pathogenic forms of P. aeruginosa strain UPM P3. Approach: Genotype characterization was carried out by amplification of the recA gene using specific primers, purified using QIA Quick PCR purification Kit and sent for sequencing. Multiple sequence alignments were performed on the selected closely related sequence accessions using CLUSTAL W software. The recA gene was used for phylogenetic and PCR-RFLP studies. Results: From the phylogenetic tree, UPM P3 has more than 90% similarity with Pseudomonas aeruginosa strains: PAM7, PAO1, UCBPP-PA14 and PA7. UPM P3 was further digested with restriction enzymes; PvuII, BsrI, ZraI, FokI and SgrAI. RFLP results showed that strain UPM P3 has close similarity with strain PAO1 of Pseudomonas aeruginosa. Conclusion: Strain PAO1 is commonly associated with strains of medical, human or plant pathogens and agricultural environment. Common habitats include soil, hosts, aquatic environment and wastewater and also a common contaminant of public places. Thus the use of Pseudomonas aeruginosa strain UPMP3 as a biological control candidate in agriculture has to be monitored

Foliar application of microbial-enriched compost tea enhances growth, yield and quality of muskmelon (Cucumis melo L.) cultivated under fertigation system

Microbial-enriched compost tea (CT) is a water extract of compost that is amended with nutrient supplements during brewing to enhance their microbial diversity. The potential use of fertigation nutrients via drip irrigation system followed by weekly foliar application of microbial-enriched CT on growth of muskmelon (Cucumis melo L.) and suppression of powdery mildew caused by Golovinomyces cichoracearum DC. was studied under rain shelter conditions. Full and half strength fertigation nutrients in combination with weekly foliar application of microbial-enriched CT, fungicide (Daconil®@2 g L−1) or water as a control were utilised in this study. The study showed that there was no added advantage in using full strength fertigation nutrients in terms of chlorophyll content, mean flower formation, mean fruit set, disease severity, and disease progress (AUDPC) or epidemic rate. A repeat trial was also conducted using half strength fertigation nutrients (twice a day) in combination with weekly foliar application of microbial-enriched CT or Daconil®, as a result there was reductions in the disease severity by 38 and 21%, respectively. In addition, a delay in disease onset for two weeks was observed in the plants treated with either microbial-enriched CT or Daconil®. The experimental results revealed significant variations in the yield and fruit qualities amongst the treatments. There were 18.3, 16.21, 8.81, 7.11 and 7.50% increases in mean fruit fresh weight (kg), total soluble solids concentration (°Brix), firmness (N), linear increment in the diameter (cm) and mesocarp size (cm) of muskmelon fruits, respectively after the application of half strength fertigation nutrients in combination with the weekly foliar application of microbial-enriched CT as compared with the control. Thus, it is rational to conclude that a reduced strength of the nutrients in the fertigation systems in combination with weekly foliar application of microbial-enriched CT could be used successfully as a biofertiliser and a bioprotectant on muskmelon crop without compromising their fruit quality

Seed-borne Infection and Development of Colletotrichum capsici in Naturally Infected Chili Seed

The testing of seeds using both the blotter and potato dextrose agar showed infection of Colletotrichum capsici to be well established both within and on the external surfaces of chilli seeds. Microtome sections showed that mycelia were present in the outer and inner layers of the testa and in the endosperm region. Formation of the acervulus was initiated below the seed coat and also in the endosperm and emerged to the surface after disrupting the seed coat. Parenchymatous tissues were also distorted. The pathogen finally grows on the seed surface