Survey and Development of an Integrated Disease Management Strategy for Banana Panama Wilt Disease in Lebanon

Abstract

Panama wilt disease, caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), is a significant threat to banana production worldwide, leading to severe yield losses in both commercial and local banana varieties. The pathogen was first identified in Lebanon in 2013. Despite its global impact, there has been limited practical research on the spread and management of banana Fusarium wilt in Lebanon. This study had three primary objectives: (1) to determine the distribution and significance of the disease in South Lebanon, (2) to evaluate the antagonistic activity of selected biocontrol agents, and (3) to assess an integrated management approach to mitigate the disease. First, a survey was conducted across 87 sites in South Lebanon to determine the current spread of the disease. A total of 260 plant samples, including both asymptomatic and symptomatic plants exhibiting wilt symptoms, were collected. The results indicated that 30% of the fields were infested with Foc TR4, demonstrating the widespread occurrence of the disease in the coastal area. Second, laboratory tests using a dual culture assay were performed to evaluate the antagonistic activity of seven Trichoderma spp. strains against Foc TR4. The results revealed that all Trichoderma isolates significantly reduced the mycelial growth of the pathogen, with T. viride strain T24 showing the highest inhibition, reducing growth by 74%. Third, an integrated management approach was evaluated through both pot experiments with artificially inoculated soil and a large-scale field trial. The field experiment, conducted in South Lebanon using a completely randomized design with four replications, involved four banana varieties: Baladi, Canarian, Grand Nain, and GCTCV2 18. The former two varieties were subjected to five treatments: a control, Trichoderma harzianum, Bacillus amyloliquefaciens (Novo Treat®), Pythium oligandrum (Polyversum®), and a combination of Bacillus subtilis + Pseudomonas putida (Fulzyme®). Disease severity assessments were based on both external and internal disease symptoms. Among all varieties tested, GCTCV 218 demonstrated the highest tolerance to Foc TR4, showing the lowest disease severity index (33%) and the highest bunch weight (31 kg). In both the Baladi and Canarian varieties, T. harzianum significantly reduced the Foc TR4 disease index, decreased endophytic Fusarium infections, and enhanced yield. In the pot experiment, T. harzianum also significantly reduced the disease index compared to the control treatment for both varieties. Fulzyme® was identified as the second most effective treatment. Given the widespread presence of the disease in South Lebanon, an integrated management approach is recommended to contain further spread and minimize damage in infested orchards. Strict sanitation measures should be implemented within and between fields. The use of tolerant or resistant varieties like GCTC V218 is advisable, along with an integrated crop management approach, including the use of biocontrol agents such as Trichoderma, B. subtilis, and P. putida. Considering the microclimate and edaphic variations between different regions, further local studies on the management of the disease are recommended.