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There are many factors influencing the ability of fungal pathogen pathogenicity. It is critical to understand the characters and the behavior of the pathogen on environmental factors influences in order to design suitable control methods for specific pathogen. In this study, different media, temperature, light density and pH levels were tested for their influence toward the Corynespora cassiicola, the causal agent for leaf spot disease of papaya. Six different media were tested in this study. Based on the result, the most suitable media for the C. cassiicola growth were Potato Dextrose Agar (PDA) half Strength and NA with 31.83 and 31.46 AUGC respectively. Meanwhile, Corn Meal Agar (CMA) showed the worst performance among those media tested with 24.09 AUGC value. Temperature of 30°C is the best for C. cassiicola growth and 12h UV 12h Light was the best combination for C. cassiicola spore production. Other than that, pH range level from 7 to 8 shows the best pH level for both growth and sporulation of C. cassiicola.

Hibiscus cannabinus (kenaf) plant is claimed as one of the fast-growing herbaceous plants with the high potential as a fiber or lignocelluloses material which is widely planted in Setiu, Terengganu, Malaysia. However, the stem rot disease was observed to be the most problematic in getting the good yields. Microbes associated with H. cannabinus that showing typical symptoms of rot-like disease were isolated using direct plating techniques. Koch’s postulates proved that Coniella musaiaensis was fungus that caused stem rot disease to kenaf out of four isolated fungi. Plant-pathogen interaction revealed the mechanism of infection by direct penetration of fungus through the outer surface of stems, since present of appressorium on the surface of host (H. cannabinus).

Papaya, Carica papaya L. is a fast-growing, semi-woody tropical herb and is one of the major fruit crops worldwide that is primarily consumed as fresh fruit. The fruits consist mostly of water and carbohydrate, and are low in calories and rich in natural vitamins and minerals. It is an economically important fruit crop grown in Malaysia with an export value of about RM100-120 million per year. In 2006, a dieback disease was detected in the west coast states of peninsular Malaysia, affecting 800 hectares with significant yield losses and resulting in the destruction of 1 million trees. Affected plants initially show greasy and water-soaked lesions on young stems, petiole axis and buds (crown parts). A total of 40 bacterial isolates were isolated from diseased crowns but only one bacterium (KD33) fulfilled Koch‟s Postulate. The bacterium was successfully identified as Chryseobacterium indologenes based on morphological characteristics and biochemical tests as described in the literature. The pathogenicity of the bacterium (C. indologenes) to its host (papaya) was confirmed by Koch‟s postulate through repeated trials in glasshouse experiments. As the disease develops, necrotic lesions spread downward into the internal tissues resulting in shrinking and drying up of seedlings, and leading to dieback and death of trees, while no symptoms were observed in control plants. The Biolog identification system was used to identify the bacterium as C. indologenes/gluem with a similarity (SIM) index value of between 0.5 and 0.74 at 24 hours of incubation. A high infection probability was recorded. Molecular genotypic identification was used to confirm that the pathogenic bacterium was truly C. indologenes with a 100% sequence similarity and no nucleotide difference between the isolate and reference strain (C. indologenes strain LMG 8337; GenBank Accession Number: NR_042507.1). Neighbour-joining phylogenetic tree analysis revealed that the bacterium belonged to the genus Chryseobac

The effects of carbon and nitrogen sources and the carbon-to-nitrogen ratio on the growth and sporulation of Exserohilum longirostratum were evaluated. Rice flour and malt extracts as the carbon and nitrogen sources, respectively, produced the greatest amount of mycelium. Sources that produced the most biomass were chosen as carbon and nitrogen sources in a C:N ratio test. However, in further experiments, glucose was chosen as the carbon source for the C:N ratio test because rice flour was found to be easily contaminated. Under the C:N ratio test (fixed carbon test), the highest spore production was obtained with a 5:1 ratio (4.78 × 106 spores/mL) and the highest biomass production was obtained with a 7.5:1 ratio (4.66 g/100 mL). In the fixed nitrogen test, 7.5:1 ratio provided the greatest output (4.08 × 106 spores/mL) whereas a 5:1 ratio produced the most biomass (4.33 g/100 mL). Meanwhile, the control which consisted of V8 agar without additional carbon and nitrogen source produced 1.07 × 106 spores/mL. These results provide information on the influence of carbon and nitrogen source and the C:N ratio that can be used in media for optimum growth and spore yield.