A Detailed Guide to the Latest Control Methods for Banana Fusarium Wilt
Banana fusarium wilt is a devastating disease, a soil-borne disease caused by infection with Fusarium oxysporum f. sp. cubense. It occurs in banana-producing areas in several provinces of southern China. There are mainly race 1 and race 4; race 1 mainly harms Fenjiao (ABB group bananas), while race 4 harms both Fenjiao and banana. It generally reduces yield by more than 20%, and severely affected fields may even have no harvest at all. Let's take a look below at the control methods for banana fusarium wilt!
Causes of the Disease
Banana fusarium wilt is a soil-borne vascular disease. Diseased banana suckers and diseased soil are the primary sources of infection. After the pathogen invades the banana through the roots, it spreads through the vascular bundle tissue toward the corm. The vascular bundle tissue at the infected site becomes noticeably brown, and there are often phenomena such as inward longitudinal splitting at the base of the pseudostem and rotting of the corm. Factors such as high temperature and abundant rain, acidic soil, sandy loam, low fertility, heavy clay soil, poor drainage, poor permeability of the subsoil, and root injury from cultivation are conducive to disease occurrence. Susceptible spring-planted bananas generally begin to show disease in June to July, worsen in August to September, and enter the peak incidence period in October to November.
Symptoms
1. External symptoms: In the adult plant stage, diseased plants first show a distinctive yellow color on the lower leaves and outer leaf sheaths. It initially appears at the leaf margins, then gradually spreads toward the midrib, contrasting sharply with the dark green parts of the leaf. Some entire leaves also turn yellow. Infected leaves quickly wilt, turning from yellow to brown and then drying up. The last top leaf often emerges late or fails to emerge, and finally the diseased plant dies.
2. Internal symptoms: Because banana fusarium wilt is a vascular bundle disease, the internal symptoms are very obvious. In the pith of the central cylinder and around it, there are yellow-red diseased vascular bundles in spot-like or linear form. The closer to the stem base, the darker the color of the lesions. The woody vessels of the roots turn reddish-brown and gradually become dark brown and dry up. The corm turns dark brown and gradually rots, with a peculiar odor.
Control Methods
1. Strictly restrict the introduction of banana suckers and Manila hemp suckers, along with the soil attached to them, from diseased areas.
2. To ensure that a banana plantation is free of fusarium wilt, disease-free banana suckers should be selected for planting. The basic method is to introduce planting material from areas without banana fusarium wilt. In addition, choose wilt-resistant varieties whenever possible.
3. If scattered diseased plants are found in a banana plantation, immediately pull them out with the roots, chop the diseased plants into pieces, put them into plastic bags, add lime, seal the bag opening, and move them out and away from the banana plantation to let them rot.
4. In order to eliminate the source of infection and cut off opportunities for spread, treating diseased soil is a very important measure.
5. Apply more fertilizer, dig ditches for drainage, and enhance plant disease resistance. In flatland severely affected banana plantations, where conditions permit, the land can be flooded and left fallow for half a year or rotated with rice.
6. For mildly diseased plants, use a broad-spectrum fungicide diluted in 30 jin of water and pour it onto the root and stem base, applying 2 to 3 times consecutively at intervals of 3 to 5 days, to promote root growth, strengthen the plants, and provide disease resistance.
7. In the middle and late stages of disease occurrence, spray an 800-fold dilution of 41% polyalthia·pyrimethanil, applying once every 3 to 7 days, or spray a 600-fold dilution of 38% famoxadone-cymoxanil onto the backs of the basal leaves.
Note: The pathogen of banana fusarium wilt can survive in the soil for more than 30 years, and no pesticide can eradicate it. So although some simple measures such as rice rotation or improvements using organic matter and soil amendments are effective, they are only partial. Comprehensive control still needs to rely mainly on using disease-resistant or disease-tolerant varieties.