Symptoms can vary slightly depending on the banana variety, the strength of the pathogen and the environmental conditions. The disease affects older leaves first and moves gradually upwards to the younger ones. The disease is characterized by yellow and wilted leaves and petioles and the splitting of the base of the stem. Diseased leaves turn brown, dry and eventually collapse at the petiole, forming a “skirt” around the stem. Yellowish to reddish streaks are visible on the stems, becoming more intense at the base. Cross sections show a reddish to dark-brown discoloration of the internal tissues, an indication of fungal growth and rotting of tissue. Eventually, all parts above and below ground rot and die.
Panama disease (also called Fusarium wilt) is caused by a subspecies of the fungus Fusarium oxyporum, that can survive in soils for decades. It enters the plant through the tiny root hairs, a process that is favored in light, poorly drained soils. It is be spread over short distances by surface water, vehicles, tools and footwear. Infected planting material, in turn, is the most common way the disease is spread over long distances. Elevated temperatures are an important component in the progression of the disease. The chlorosis of leaves and the lack of plant vigor occurs due to the decay of the transport tissues in the stem which leads to impaired water and nutrient transport. If all conditions are met, Fusarium wilt can be a very destructive disease in banana.
The application of biocontrol agents such as the fungus Trichoderma viride or the bacteria Pseudomonas fluorescens in the soil are effective methods to decrease the incidence and severity of the disease.
Always consider an integrated approach with preventive measures together with biological treatments if available. Contrarily to other fungal diseases in banana fusarium wilt, once detected, cannot be controlled with fungicides. Dipping plantlets in specific fungicides (10g/10 litres of water) followed by drenching of the soil every second month starting 6 months after planting is recommended.