By: Liz Baessler
Papaya stem rot, sometimes also known as collar rot, root rot, and foot rot, is a syndrome affecting papaya trees that can be caused by a few different pathogens. Papaya stem rot can be a serious problem if not addressed properly. Keep reading to learn more about what causes papaya stem rot and tips for controlling papaya stem rot disease.
Stem rot on papaya trees is a syndrome rather than a specific disease, and it has been known to be caused by a number of different pathogens. These include Phytophthora palmivora, Fusarium solani, and multiple species of Pythium. These are all fungi that infect the tree and induce symptoms.
Stem rot, no matter the cause, tends to affect young trees the most, particularly when they have recently been transplanted. The stem of the tree will become water soaked and weak, usually right at ground level. This water-soaked area will develop into a brown or black lesion and begin to rot.
Sometimes a white, fluffy growth of fungus is visible. The leaves may turn yellow and droop, and eventually the entire tree will fail and collapse.
The fungi that cause papaya stem rot thrive in damp conditions. Waterlogging of the tree’s roots is likely to lead to stem rot. The best way to keep the fungus from taking hold is to plant your papaya saplings in well-draining soil.
When transplanting, make sure the soil line is at the same level on the trunk that it was before – never build up the soil around the trunk.
When planting saplings, handle them with care. Injury to their delicate stems creates a gateway for fungi.
If a papaya tree shows signs of stem rot, it can’t be saved. Dig up infected plants and destroy them, and do not plant more trees in the same spot, as stem rot fungi live in the soil and will lie in wait there for their next host.
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Read more about Papaya Trees
The cooler climate of North America limits the cultivation of many favorite tropical fruits, such as the papaya (Carica papaya). Gardeners, however, can attempt papaya plant care when they are grown as an annual, in a sheltered location, in a greenhouse or as a potted plant.
Papaya trees grow in U.S. Department of Agriculture plant hardiness zones 10 to 12, according to the Missouri Botanical Garden. As the University of California Davis notes, papaya trees are vulnerable to cold and require protection from all frost. When papaya is grown as an annual, the fruit is picked while still green, before the frost kills the tree. The papaya requires a long, warm growing season rich, moist, well-drained soil (as the University of Hawaii Manoa Extension highlights) and minimal pruning.
The melon-like papaya fruit grows from seeds mostly in warm, tropical climates. With the proper soil selection and care, the papaya plant can produce an abundance of fruit. By contrast, however, overwatering and poor soil drainage can cause deadly papaya diseases like root rotting. Among the additional culprits include necrosis, ringspot, and leaf spot, as well as anthracnose. Some other diseases that attack the papaya include blight and powdery mildew.
Papaya plants must be properly watered according to instructions otherwise, too much water can lead to root rot. This condition quickly kills the papaya fruit because of the lack of drainage at the planting site. Poor water drainage cuts off oxygen to the plant and it also causes fungi to form, causing more damage to the papaya. One way to avoid root rot disease would be to plant papaya seeds in raised planting beds or in garden spaces with better water drainage.
Improper plant care also leads to other papaya diseases such as necrosis. Also known as papaya apical necrosis, this virus causes the plant's leaves to droop and cup downward, turning yellow or brown. The papaya disease starts with the leaves and stems, then progresses until the papaya plant dies. The virus disappears once a gardener destroys and removes the papaya plant, according to experts.
Another papaya-related virus, ringspot, occurs from lack of plant care. Key symptoms include yellowing of the leaves, followed by dark-green streaks. Dark-green C-shapes and circles also form on the papaya fruit when infected by the virus. Planting techniques, such as grafting, increase the risk of ringspot to the papaya. Isolating the plant can get rid of the ringspot problem.
Corynespora leaf spot is a disease caused by a fungus. The papaya disease appears mostly on the leaves and male flower stalks of the plant, rather than the fruit. The fungus is identified by brown and yellow spots, along with spores that appear on the leaves. Gardening experts recommend applying fungicide to the affected papaya to eradicate the disease.
Anthracnose is another one of the papaya diseases that derives from a fungus. This particular condition affects the fruit as opposed to the flower stalks and leaves. Symptoms of anthracnose start with water-soaked spots that appear on the papaya fruit. The spots may grow, turn brown or black, and then sink into the fruit and damage the pulp. Fungicide applied to the papaya plant treats anthracnose, especially in the disease’s early stages.
Phytophthora blight is considered among the deadliest of papaya diseases. Caused by heavy wind and rain, this fungus often causes wilting, stem and root rot, as well as root and fruit infection. Signs of phytophthora blight include water-soaked lesions in the branches and fruit, followed by browning and rapid deterioration of the entire papaya plant. The lesions often turn white on the fruit, causing shriveling. Like the other fungus-based papaya diseases, phytophthora blight can be tamed by using fungicide sprays.