Micrograph analysis of morphological alteration and cellular damage of fruit rot fungal pathogens treated with Averrhoa bilimbi fruit and Garcinia mangostana pericarp ethanolic extracts.

The aim of this study is to assess the antifungal action of Averrhoa bilimbi fruit and Garcinia mangostana pericarp ethanolic extracts in altering the morphology and causing cellular damage of Fusarium oxysporum, Fusarium proliferatum, Colletotrichum gloeosporioides and Lasiodiplodia theobromae. The pathogens were cultured on media containing both extracts individually and carbendazim as positive control, whereas media alone as negative control. All samples were processed for microscopy observations using scanning (SEM) and transmission electron (TEM) microscopes. Observation via SEM showed significant alterations in the hyphae of F. oxysporum, F. proliferatum and C. gloeosporioides compared to the control in which the hyphae were in normal form. However, no significant alteration in hyphae had been observed in the treated plate compared to the control for L. theobromae. The development of calcium carbonate crystals was also observed abundantly in control compared to treated pathogens for F. oxysporum and F. proliferatum only. This indicated that the plant extracts can inhibit some metabolic processes in the pathogens too. Observations via TEM had been conducted for F. proliferatum and C. gloeosporioides, respectively. The results showed disintegration of cytoplasmic organelles and cell wall, intense vacuolization and lyses part of fungal cells. The plant extracts have equivalent or even greater effects compared to commercial fungicide carbendazim.

Biocontrol efficacy of Trichoderma asperellum-enriched coconut fibre against Fusarium wilts of cherry tomato.

AIMS: Agro-based wastes were evaluated as a medium for mass micropropagule production and optimal efficacy of Trichoderma asperellum B1092 in controlling Fusarium oxysporum f. sp. lycopersici and promoting tomato growth. This study focused on biological control because pathogen persistence in the soil makes the disease difficult to control. METHODS AND RESULTS: Rice bran, biochar, empty fruit bunches, coconut fibres, compost, top soil and mixed soil were evaluated as media for mass multiplication of T. asperellum, which is effective in controlling plant pathogens. Yielding the most colony forming units (CFU) among the media, coconut fibre was deemed most suitable for promoting sporulation. After 120 days on the medium, T. asperellum B1902 produced 9·053 × 105  CFU per gram coconut fibre; oil palm empty fruit bunches was second highest (7·406 × 105  CFU per gram). In field tests of T. asperellum B1092 against F. oxysporum f. sp lycopersici (causing Fusarium wilt of cherry tomato), B1092 significantly promoted plant growth compared to the control. The efficacy of this formulation resulted in increased growth of roots and shoots tomato plants and total lycopene, sugar, K, N, Ca, P and Mg content after 120 days. CONCLUSIONS: Trichoderma asperellum B1092 showed great field potential for improving productivity and quality of tomatoes and in controlling Fusarium wilt of cherry tomato. SIGNIFICANCE AND IMPACT OF THE STUDY: This innovative approach using a cheap agro-waste to control the persistent soil-borne Fusarium pathogen of cherry tomato should increase soil survival rate of Trichoderma and has potential for upscaling in the field for other crops.

Genetic diversity and pathogenicity of Fusarium species associated with fruit rot disease in banana across Peninsular Malaysia.

AIMS: The aims of this study were to identify the Fusarium isolates based on translation elongation factor (tef) 1α sequence, to determine the genetic diversity among isolates and species using selected microsatellite markers and to examine the pathogenicity of Fusarium isolates causing fruit rot disease of banana. METHODS AND RESULTS: One-hundred and thirteen microfungi isolates were obtained from fruit rot infected banana in Peninsular Malaysia. However, this study was focused on the dominant number of the discovered microfungi that belongs to the genus Fusarium; 48 isolates of the microfungi have been identified belonging to 11 species of Fusarium, namely Fusarium incarnatum, Fusarium equiseti, Fusarium camptoceras, Fusarium solani, Fusarium concolor, Fusarium oxysporum, Fusarium proliferatum, Fusarium verticillioides, Fusarium sacchari, Fusarium concentricum and Fusarium fujikuroi. All Fusarium isolates were grouped into their respective clades indicating their similarities and differences in genetic diversity among isolates. Out of 48 Fusarium isolates tested, 42 isolates caused the fruit rot symptom at different levels of severity based on Disease Severity Index (DSI). The most virulent isolate was F. proliferatum B2433B with DSI of 100%. CONCLUSIONS: All the isolated Fusarium species were successfully identified and some of them were confirmed as the causal agents of pre- and postharvest fruit rot in banana across Peninsular Malaysia. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results will provide additional information regarding new report of Fusarium species in causing banana fruit rot and in the search of potential biocontrol agent of the disease.