Bird of paradise plants, with the scientific name Strelitzia, are tropical herbaceous perennials native to South Africa. Their name is derived from the resemblance of their crane-like flowers to actual birds of paradise, although some plant growers call them banana trees, since they also look like banana plants. These regal plants are resilient and pest-resistant, but they can be prone to infections and fungal diseases such as root rot. To learn more about this potentially fatal condition, keep reading.
Bird of paradise root rot: Signs and symptoms
The roots are soft and brown.
If your plants look sickly, distressed or lifeless, check their roots. Root rot is hard to detect in its early stages, since it starts underground and the roots are the first victims. If the roots are dark brown and fall off when shaken, they have become rotten. They will also become soft and mushy with an unpleasant smell, unlike healthy roots which are succulent and white.
The stems are swollen and mushy.
Be concerned if the stems of your bird of paradise plants are swollen and feel mushy. Check the roots for any rot and be aware that the signs often start at the base of the stem and progress from there. The stems also tend to look curled, smaller than normal, or twisted. Their color may change and their bases will begin to smell unpleasant due to the rot.
The plant’s growth is stunted.
If you notice that there is no new growth or your plants have stunted growth, it could be a sign of root rot. The new leaves will be smaller than usual, and turn yellow and wilted. Plants affected with root rot are also unlikely to bloom despite correct fertilization, watering and light conditions.
Nevertheless, you need to rule out other potential causes of stunted growth, such as nutrient deficiencies, poor soil pH, low light, temperature stress, salt buildup and poor watering habits.
The leaves are discolored.
If you notice that the leaves of your plants are turning yellow, they could have root rot. Most often, plants with root rot suffer from yellowing of at least 60% of their foliage. The leaves turn yellow, wilt and eventually drop off, with this yellowing usually starting at the base of the plants. The edges of the leaves could also turn brown and eventually become wilted and drop off or die.
Root rot aside, a plant’s leaves may also turn yellow because of nutrient deficiencies, sunburn, pest infestation, soil toxicity and edema.
The plants are wilting.
If you notice the foliage wilting on the lower part of your bird of paradise plants, it could be an indication of root rot. This is due to insufficient water absorption by the roots, and is the plant’s way of protecting itself from becoming dehydrated. Other reasons your plants might wilt include over- or underwatering, cold drafts, pests, and temperature stress.
The shoots are dying back.
If the shoots of your plants are dying back, it is most likely due to root rot. The fungal disease destroys the roots, leaving the plants unable to absorb nutrients for the growth of new shoots. However, shoot dieback could also be due to a lack of humidity, chemical buildup, overwatering, pests, and too much or too little sunlight.
Causes of bird of paradise root rot
When the plants are overwatered, the soil becomes waterlogged and the roots struggle to breathe. Roots need oxygen to survive and waterlogging chokes off the oxygen supply, killing the roots and making them susceptible to diseases and pathogens. Overwatering can also cause brown or yellow leaves.
2. Poor drainage
Your plants’ potting mix or soil may retain water too well due to poor drainage capacity, in which case it will become soggy. When soil is waterlogged it hardens like cement, making it difficult for oxygen to reach the roots, and thus leaving the roots susceptible to root rot. To correct this, add more mulch, perlite, sand or compost to amend the drainage capacity. Also see to it that the pot has draining holes on the bottom.
3. Fungal infections
Root rot can be caused by several species of fungi, although it is often hard to distinguish exactly which is affecting your plants. Fungi thrive in old, damp containers, soil or infected tools, and may use these as vectors to move from one plant to another. Some common root-rot causing fungi include Phytophthora, Pythium and Fusarium solani.
4. Incorrect pot size
Oversized pots hold more soil and thus more moisture than necessary, and could create waterlogged areas that lead to root rot. If the container is too small, on the other hand, the plant could become rootbound and the tangled roots could prevent drainage and air flow through the soil. To correct this, place your plants in containers that are neither too large nor too small for them. When transplanting, the new pots should be a half-inch larger than the current pots.
5. Low temperature
Another cause of root rot is low temperature. This fungal infection thrives in wet conditions and temperatures of 70 to 86 degrees Fahrenheit. The plants also tend to absorb less water during cold weather, allowing the soil to remain wet for longer periods.
6. Watering during the dormant period
Birds of paradise plants are tropical to semi-tropical plants, so when temperatures drop to around 50 degrees Fahrenheit, they will become dormant. In this state, they will not absorb as much water as during their growing season, so if you do not adjust your watering routine, their soil will remain moist for far too long. To fix this remove the plants and let the soil dry out before replanting them. Remove any dead leaves, roots or other plant parts and wait until the soil has dried out before watering them again.
How to treat bird of paradise root rot
These are the steps for treating and preventing root rot:
- Stop watering the plants until they have had a chance to dry out.
- Remove infected leaves and other plant parts.
- Remove the plants from their pots, trim off the affected roots and allow the remaining roots to dry out.
- Repot the plants using new soil and new pots.
Bird of paradise root rot can be treated with chemical or organic treatments. The most common are commercial copper-based and sulfur-based fungicides. There are also homemade treatments, including charcoal, cinnamon and chamomile.
Bird of paradise plants are tropical herbaceous plants that are native to South Africa. They have crane-like flowers that resemble birds of paradise, and are popular as indoor and ornamental plants. These are relatively hardy plants; however, they are still prone to diseases such as root rot, which can be caused by overwatering, poor drainage, fungal infections or low temperatures. To save a plant with root rot, you will need to remove it from the pot, prune away the infected roots, apply fungicide on the healthy roots, and repot the plant in a new pot, using fresh soil.
Image: istockphoto.com / Lutique