Abstract
Phytopathogens are known to be the leading cause of important plant diseases which result in significant losses in agricultural crops. The need to maintain the level of yield both quantitatively and qualitatively is vital in order to curb the losses. So far there has been a positive advance recognized in research to the use of tropical fungi as biocontrol agents. The objective of this study was to screen for antagonistic tropical fungi against selected phytopathogens of maize (Zea mays L.) and beans (Phaseolus vulgaris L.) namely Fusarium graminearum, Fusarium moniliforme, Pythium ultimum, and Colletotrichum lindemuthianum in vitro. A total of 87 tropical fungi isolates were collected from Kakamega tropical rainforest, Kenya. Dual culture experiment was carried out to screen the tropical fungi against the selected phytopathogens. The bioassay was performed in a completely randomised design in triplicate and the inhibition zones recorded after every week for three weeks. Differential biocontrol ability among nine tropical fungi was noticed against F. moniliforme with the percentage inhibition increasing over time. Fusarium solani was the most active antagonist with an inhibition of 64% while Phaeomarasmius sp. had the lowest activity of 19.1% against F. moniliforme. Epicoccum sp. inhibited the mycelial growth of P. ultimum by 38% and also inhibited C. lindemuthianum by 58%. None of the fungal antagonists inhibited the mycelial growth of F. graminearum. The outcome of this study indicates that tropical fungi can be used as biocontrol agents and can be further explored and developed into effective fungicides for management of phytopathogens.
Highlights
Plant diseases, in particular pathogens, play a direct role in the destruction of natural resources in agriculture causing important losses, fungi being the most aggressive (Abou-Zeid et al, 2008; Yu et al, 2010)
The present study addressed the biocontrol efficacy and mechanisms of tropical fungi as biocontrol agents against selected phytopathogens of maize and beans
Antimicrobial activity of tropical fungi against the four phytopathogens: Nine different isolates of tropical fungi inhibited the mycelial growth of F. moniliforme (Table 1) while one isolate (Epicoccum sp.) inhibited the growth of P. ultimum and C. lindemuthianum
Summary
In particular pathogens, play a direct role in the destruction of natural resources in agriculture causing important losses, fungi being the most aggressive (Abou-Zeid et al, 2008; Yu et al, 2010). Maize and beans are staple foods and a major source of dietary in most homes in Kenya due to their nutritional composition. These two crops are an important key determinant of food security for small holder farming communities. Disease outbreaks are key constrain to maize and beans production. Yield losses of up to 90% as a result of maize lethal necrosis led to grain loss of 126,000 metric tons valued at $52 million in Kenya in the year 2012 (Mahuku et al, 2015).
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