This archive report was first published on 9 November 2019.
As the mango season gets underway, farmers in Makueni are bracing themselves for a potential disaster. The reason: two devastating diseases that can decimate their crops and leave them with significant post-harvest losses.
According to experts, bacterial black spot and powdery mildew are the two main diseases affecting mangoes in the region. Bacterial black spot, caused by a bacterium, affects leaves, stems, and fruits, causing black angular greasy spots between the veins, which can lead to a significant reduction in photosynthetic area and high rates of leaf fall.
Affected fruits have black oval to irregular raised spots, which develop with greasy margins, affecting their quality and leading to rejection or lower selling prices. The disease is easily spread by windblown rain, splash water, and insects, and can be severe in both high and low rainfall areas.
On the other hand, powdery mildew, caused by fungi, attacks the inflorescences, leaves, and young fruits, causing them to appear whitish and fail to open, resulting in flower abortion. The disease can also affect young fruits, causing them to fall prematurely, leading to significant losses due to poor fruit set and dense flower abortion.
Experts warn that the diseases can be severe if not controlled, and recommend that farmers take preventive measures such as buying clean planting materials, selecting varieties that are resistant and tolerant to the disease, and maintaining field hygiene. They also advise against overhead irrigation, which can help spread the disease, and recommend the use of drip irrigation in dry areas.
Pruning should also be done to avoid overcrowded leaves, which makes it hard to spray, and all pruning shears should be sterilized after pruning each tree. By taking these measures, farmers can reduce the risk of these diseases and ensure a healthy and productive mango crop.
