Plumeria root rot happens when the roots of the tree are constantly submerged in waterlogged soil. When the soggy soil surrounds the roots, it creates an anaerobic environment that starves the roots of oxygen and encourages opportunistic pathogens to attack. The roots will rot and the decay will move up to the stem, which results in the much more debilitating stem rot.
In this article, we will discuss the causes of plumeria root rot and how to save your affected tree.
What is plumeria root rot?
If you give your tree more water than it needs, the excess water will pool around the roots and suffocate them. When the roots suffocate, they will become clogged and die. The fine hair rootlets, once dead, will rot, and this rot will travel up to the main root system. This is root rot.
If the plant is in a pot that does not have drainage holes at the bottom, the excess water will not have a way out and will pool in the soil near the bottom of the pot, resulting in the same symptoms as overwatering, above.
Likewise, if the soil in the pot is poorly-draining, or if the soil is heavy and compact, it will hold onto moisture too well and the roots will not be able to breathe or dry out fast enough.
Overwatering can also happen if you water the tree just as much in the winter as you do in the summer. In low winter temperatures, the soil will not dry out as quickly as it does in the summer, so unless you adjust your watering schedule, you will end up with soggy soil.
Root rot is exacerbated and spread even more quickly by fungi. The most common fungi species that cause root rot are Fusarium, Pythium and Rhizoctonia. The spores of these fungi may have been lying dormant in the soil for years, just waiting for the perfect opportunity to attack a nearby tree with rotting roots.
The fungal disease moves up from the roots to the stem, where it inflicts even more damage. The stem will literally hollow out and rot from decay. Stem rot is a death sentence for the tree because the nutrients and water will no longer be able to pass through the damaged stem to the rest of the tree.
Root rot disease caused by pathogens is spread through unsterilized tools and contaminated soil or water.
If you have a plant that has died of root rot, and if you were not able to remove all of the diseased roots from the soil, the dormant spores can infect the next plant you place in that same spot.
How to avoid root and stem rot in plumeria
You can avoid root and stem rot by practicing good hygiene when you handle your plants. Make sure the area around the tree is free of debris that can be a breeding ground for fungi.
If you plan on removing cuttings to propagate, make sure you apply some fungicide on them before planting them in potting medium.
Plant your cuttings in several small pots instead of one large tray. This is because the chances of spreading the disease are higher when the plants are right next to each other.
Avoid using livestock manure as fertilizer on the plumeria.
Choose soil that is well-draining. If you cannot find commercially available potting mix, you can make your own by simply adding one part perlite/coarse sand to one part potting soil. The perlite or coarse sand will make the potting soil porous and airy. This way, the plant’s roots will be able to breathe and will dry out much faster between waterings.
Refrain from overwatering your tree. Do not stick to a strict schedule, as the need for watering will depend on the weather and the climate. A more accurate way of knowing whether the tree needs to be watered is by touching the soil around the base of the tree. If the soil is dry, water the plant, but if the soil is still damp, wait a few days and check it again.
Remember that you need to adjust your watering schedule in the winter. You are going to have to water the tree significantly less when the weather is cold, because the soil will not dry as quickly and there is less light to warm it and help it dry.
Plumerias can tolerate low light, but that does not mean you can completely deprive the plant of light. If you keep the plant indoors, do not transfer it from low light to full sunlight immediately. You need to give the tree an adjustment period for it to get used to more and more light exposure so that it does not get sun damaged.
You can help the tree out by buying a grow light to provide the plant with the light it needs during the winter.
If you notice the first signs of root or stem rot, you can try applying fungicide to catch the disease in its early stages.
However, if the stem rot has become too severe and the tree cannot be salvaged, take a cutting and try to root it so you can grow yourself a new plumeria tree.
Plumeria trees can get root rot if their roots are left to stand in waterlogged soil for extended periods of time. This can come about if you overwater your plant, if the pot does not have drainage holes, if the soil you use is not well-draining, or if there are fungal pathogens in the soil or in the tools you use. These opportunistic fungi will attack the vulnerable roots of the tree and cause root and stem rot. When the stem is severely damaged, nutrients and water can no longer travel to the other parts of the tree, which will most likely lead to its death.
Save your plumeria by removing damaged roots and treating the remaining roots with fungicide before replanting it in a pot with sufficient drainage holes and well-draining soil.
Image: istockphoto.com / Yana Tatevosian