By Umar Nsubuga
Pawpaw, also known as papaya, is a nutritious and popular fruit grown in many parts of Uganda. However, like other crops, pawpaw is vulnerable to various diseases that can significantly impact yield and quality.
To help farmers prevent these issues, Patrick Kirunda, a seasoned pawpaw farmer in Bumozi village, Bugweri district, and Henry Sekyewa, an agronomist, share essential strategies for managing common pawpaw diseases.
Disease-resistant varieties
One of the most effective ways to combat diseases in a pawpaw garden is to start with disease-resistant or disease-tolerant varieties.
“Selecting the right seeds from the beginning can make a big difference,” says Kirunda.
He says disease-resistant varieties are less likely to succumb to common infections and can reduce the need for chemical treatments. Seek advice from local agricultural experts on the best varieties suited to your area, as these often have natural resistance to regional diseases.
Ensure proper site selection and garden layout
Proper site selection is critical in preventing disease.
Sekyewa emphasises the importance of choosing a location with well-drained soil to prevent waterlogging, which can lead to root rot.
“Pawpaw plants are very sensitive to excess moisture. Waterlogged soils encourage fungal growth, especially Phytophthora, which causes root rot,” he explains.
Spacing is also essential to prevent disease spread. Kirunda recommends planting pawpaw trees at least 8 to 10 feet apart to allow good air circulation, which reduces humidity around the plants and lowers the risk of fungal diseases.
Keeping weeds under control and removing plant debris from around the trees can minimise disease vectors and create a healthier environment for the plants, he adds.
Practice crop rotation and avoid overcrowding
Crop rotation can help prevent soil-borne diseases from taking hold.
“Avoid planting pawpaw in the same area year after year, as this can lead to a buildup of pathogens,” Sekyewa advises.
By rotating with non-host crops, such as legumes, he explains that farmers can disrupt the life cycle of certain diseases and pests that specifically target pawpaw.
“Overcrowding is another risk factor, as it can restrict airflow and increase moisture,” he notes.
Sekyewa suggests maintaining ample space between plants and regularly pruning dense foliage to improve air circulation, as this can help reduce the likelihood of fungal infections.
Regular monitoring and early detection
“Early detection is vital in fighting pawpaw diseases,” says Kirunda.
Regularly inspecting plants for signs of infection can help identify diseases early, when they’re easier to control.
“Key symptoms to watch for include leaf spots, yellowing leaves, wilting, and mold growth on leaves or stems. Once you identify an issue, take prompt action to prevent it from spreading to healthy plants,” he explains.
For example, black spot, a common disease in pawpaw, manifests as dark spots on the leaves and fruits. He says If spotted early, infected leaves should be removed and destroyed. Avoid composting these leaves, as the disease can survive and re-infect plants.
Use organic and chemical control methods appropriately
While chemical fungicides and insecticides can help manage certain diseases, Sekyewa advises caution in their use.
“Excessive or improper use of chemicals can harm beneficial insects and soil microorganisms, which are essential for healthy plant growth,” he explains.
He encourages farmers to use organic methods whenever possible, such as applying neem oil or garlic sprays, which have natural antifungal and antibacterial properties.
“Always follow recommended doses and application schedules. Rotating between different types of fungicides can also help prevent resistance in pathogens, which makes the treatments more effective over time,” he explains.
Improve soil health with organic matter
Healthy soil is one of the best defences against pawpaw diseases.
Kirunda advocates for regular additions of organic matter, such as compost and well-decomposed manure, which enrich the soil with nutrients and improve its structure.
“Good soil promotes strong, healthy plants that are better able to resist diseases,” he notes.
He says organic matter also encourages beneficial microbes that help control harmful pathogens.
“Mulching around pawpaw trees can retain soil moisture and suppress weed growth, reducing competition for nutrients and supporting the health of the trees,” he states.
However, Sekyewa advises keeping mulch away from the trunk to prevent moisture accumulation, which can promote fungal infections.
Control pests that spread disease
Pests like aphids and whiteflies not only damage pawpaw plants directly but can also spread viruses.
“It’s important to manage these pests early to prevent disease transmission,” says Sekyewa.
He recommends using yellow sticky traps to monitor and control flying pests, or introducing beneficial insects like ladybugs, which prey on aphids. Regularly removing heavily infested leaves can also help reduce pest populations.
