Disease severity associated with the pathogen Fusarium oxysporum is generally thought to be proportional to the population of fungal propagules in the soil. However, results from studies using naturally infested soil are contradictory, implicating host predisposition to disease. In this study, soil was amended with chicken manure to investigate the interdependence between the activity and invasiveness of the pathogen, and the incidence of Panama disease in susceptible banana plantlets. Two soil types naturally infested with either race 1 or race 4 of the pathogen, and cultivars Lady finger and Grande Naine, were used. Pathogen activity was measured by burying root tip segments for 5 days, then calculating the frequency of isolation of Fusarium from the segments. Pathogen invasion was measured by transplanting banana plantlets into trays of amended and unamended soil for 4 weeks, then calculating the frequency of recovery of Fusarium from each pseudostem. Amending both soil types with chicken manure enhanced both pathogen invasion and disease incidence. However, pathogen activity was not correlated with either parameter. We postulate that the addition of chicken manure is predisposing banana plantlets to Panama disease, by reducing the efficacy of the host wound response.

Fusarium wilt symptoms were observed on 15 different banana cultivars growing in commercial plantations and backyard holdings, in 6 districts in the Province of West Sumatra, Indonesia. Affected cultivars included the most popular dessert bananas Pisang buai (AAA), Pisang raja (AAB), Pisang raja serai (AAB), and Pisang ambon (AAA). Disease symptoms were also observed on the most popular cooking banana Pisang kepok (ABB), formerly considered to be resistant. However, no disease symptoms were observed on wild Musa species. The 37 isolates of the pathogen Fusarium oxysporum f. sp. cubense (Foc) recovered from the vascular tissue of the diseased bananas were assigned to the vegetative compatability groups (VCGs) 0120–01215, 0124, 01213–01216, 01218, and 01219. VCG 01216 was isolated from all districts, and from 14 of the 15 cultivars exhibiting wilt symptoms. However, the distribution of the other VCGs was more variable, reflecting the patterns of human migration within the different districts. Districts designated as expanding urban centres or as transmigration centres had a higher diversity of banana genotypes present, with a correspondingly higher diversity of VCGs isolated from the diseased plants. The traditional practice of transplanting banana suckers and rhizomes irrespective of the disease status of the parent plant, and the recent increase in the mobility of the Indonesian population, indicate that disease control strategies based on quarantine will not be effective. Accordingly, the selection of both popular dessert and cooking banana cultivars with resistance to VCG 01216 should be a priority for the control of Fusarium wilt in West Sumatra.

No abstract

Blood diseases caused by Ralstonia solancearum Phylotype IV is a major cause of production loss of banana in Indonesia, particularly for areas in West Sumatera. Currently there is a lack of information on blood diseases. The objective of this study was to obtain data of insect diversity and its potential as a dissemination agent of R. solanacearum Phylotype IV in West Sumatera. This research was conducted with a purposive sampling method in the Tabek Panjang highlands, District of Baso, Agam Regency and Pasar Usang lowland, district of Batang Anai, Pariaman Regency, West Sumatera. The results showed that banana plants infected by R. solanacearum Phylotype IV have a high diversity of flower-visiting insects. The diversity of insects in the lowlands is higher than that in highland and mainly are dominated by Trigona spp. (Hymenoptera: Apidae), Drosophila sp. (Diptera: Drosophilidae). To test the potential of both insect as vector of the blood diseases, isolated and identification of the bacteria using triphenyl tetrazolium medium chlorid (TTC) was used. Result showed that bacteria isolated from both insect are R. solanacearum hence providing evidence of the insect as vector of the blood diseases. Both insects have the potential to be vector of R. solanacearum Phylotype IV in West Sumatera. The identification of the bacteria that causes the disease. The identification of bacteria that is spread by flower visitors insects are R.solanacearum Phylotipe IV.

Abstract. Despite extensive research since pathogenicity was first established in 1919, no cultural or chemical control strategy has proven effective against Fusarium wilt of bananas. The efficacy of cultural control is attributed to the suppression of pathogen activity. Yet, amending naturally infested soil with aged chicken manure has been shown to enhance disease severity, without any change in the activity of the pathogen Fusarium oxysporum f. sp. cubense (Foc) in the soil. In this study, the effect of amending soil with composted sawdust, and of solarising soil, was compared with the effect of amending soil with chicken manure. Bioassays comparing the activity of Foc in the soil with the extent of invasion of banana pseudostem tissue by Foc were used to investigate why strategies targetting pathogen survival have not proven successful in controlling this disease.The enhancement of Foc invasion of the banana plantlets was reproduced with the addition of chicken manure to the naturally infested soil. However, changes in the activity of Foc in the soil were not associated with changes in the frequency of invasion of the plantlets. Invasion of banana pseudostems in the sawdust and solarisation treatments was not significantly different from invasion in the respective control treatments, despite a reduction in the activity of Foc in the sawdust-amended soil and an enhancement in the solarised soil. Moreover, the increase in Foc activity in the solarised soil recorded during the bioassays occurred despite the effectiveness of solarisation in reducing the survival of Foc in pre-colonised banana root tips buried in the soil. Changes in the frequency of invasion were associated with changes in the availability of mineral nitrogen, particularly ammonium N. These results suggest that the physiological response of banana cultivars to ammonium N may be associated with their susceptibility to Fusarium wilt. Accordingly, cultural strategies for controlling Panama disease will only be effective if they enhance the ability of the host to resist invasion.A R 0 2 0 9 9 E f f e c t o f o r g a n i c a m e n d m e n t s a n d s o l a r i s a t i o n o n F u s a r i u m w i l t N . N a s i r e t a l .