Hibiscus Dieback Disease is typically caused by damage to the bark of a hibiscus plant’s stem. Damage may be caused by inclement weather, insect damage, pruning, impact, or other events that compromise the plants’ bark.
Injured bark allows bacteria (Erwinia sp) or fungus (Botrytis) to enter the plants’ tissues and can cause disease. In some cases, bacteria or fungus may be introduced by a spent bloom that does not fall entirely away from the plant.
What Can Cause For Hibiscus To Have Dieback Disease?
If it gets stuck against the plant’s stem and then begins to decay, it will cause stem rot and disease. This is most likely to happen in cool, damp weather when fungal spores are abundant.
Occasionally, bacteria or fungus will take hold in a damp flower. The infection will spread to the plant through the flower’s stem when this happens.
In all of these instances, you may be able to stop the rot from spreading because it starts at a single point on the hibiscus plants’ stem, so the plant is only partially affected.
This is a genuine dieback disease. If you can identify it quickly enough, prune away the damaged tissues and treat the pruned surfaces with the appropriate antifungal or antibacterial product, you should be able to save your plant.
If the infection starts low on the plant (or in the roots) and spreads to the entire plant, you are actually dealing with wilt disease. In this case, you are often better off simply destroying that plant and starting over.
How Can You Tell If Your Hibiscus Has Dieback Disease?
When dieback is caused by bacteria introduced by injury to bark, the bacteria will move through the affected area of the plant and accumulate in the tips of the stems.
In this case, the damage to the plant will begin at the stem tips and spread downward. Existing leaves will fall, and no new leaves will grow. The affected portion of the plant will simply become diseased and unhealthy while yet-to-be-affected parts continue to do well.
If a fungus causes the dieback (e.g., Botrytis cinerea, Botrytis blight, or Gray mold), you will notice that papery, tan spots or gray, fuzzy mold spots mar the flowers.
You may also see round brown or tan leaf spots in the shape of concentric circles. You will especially notice this if affected flowers have fallen, become stuck, and come in prolonged contact with the leaves.
How Can You Treat Dieback Disease?
If your plant is affected in one area by dieback disease, prune the damaged parts off completely and neatly. For outdoor hibiscus, it is best to do this in the springtime.
Follow these steps to prune away diseased parts of your plant:
1. When pruning, remember to use a very sharp, sterile cutting implement. Sterilize the blades between cuts.
2. Before pruning, carefully examine your plant to determine where the infection began. This will be a discolored or damaged area of the stem. You may see that the leaves just above the wound are wilted.
3. To remove the infected part of the stem, look below the wound and identify where the healthy stem begins.
4. Make a clean cut at a 45-degree angle, a quarter inch above a node located on a healthy part of the stem.
5. Put the damaged branch or stem right into the trash. Don’t lay it on the ground or put it in compost, as this will allow the disease to spread.
6. Examine the cut you have made. You are done if the wood inside the branch looks healthy, white, and clean. If it’s dark or streaky, you need to cut it off more. You can continue working your way down the branch until you find clean wood, or to be entirely safe, just cut the whole branch off.
7. When you finish pruning, seal the cuts with canning or grafting wax. Another option is to paint the cut with a Copper biocide. Be sure to follow the packaging instructions when using this product.
How Can You Prevent Hibiscus Dieback Disease?
Practicing good hygiene and plant care habits will help prevent this disease.
Follow these tips to prevent Hibiscus Dieback Disease:
1. Be sure to wash up before handling and pruning your plants. Wear disposable gloves, and change them between plants.
2. Prune away the dead wood, damaged branches, and foliage promptly and neatly.
3. Do not overcrowd your plants.
4. Maintain good air circulation to discourage mold growth.
5. Avoid frequent overhead watering. Water in the morning, at ground level, to keep the soil moist, not soggy. During very dry weather, you can give your plants a thorough shower a couple of times a month on bright, dry days.
6. Be vigilant about insect pests. Deal with them promptly to prevent them from causing damage to your plants.
7. Remove garden debris and weeds near your hibiscus plants.
8. Keep your soil healthy with worm castings, organic matter, and beneficial fungi amendments.
9. Deadhead your hibiscus promptly to remove blooms when they begin to fade.
10. Be sure to cut away the flower stems completely and neatly.
11. Avoid handling or pruning your plants during wet weather.
12. Apply fungicidal products promptly if you notice even the slightest mold development. Recommended products include:
- Potassium bicarbonate
- Copper hydroxide
Be sure to choose the right product for indoor or outdoor use. Follow packaging directions carefully for best results.
Healthy Hibiscus Plants Fight Off Pests & Disease
If you can provide your hibiscus with the sun, warmth, fertile soil, steady moisture, and shelter from harsh winds it needs to survive and thrive, it is far less likely to become diseased, even if its bark is damaged.
It will also be better able to fight off pest infestation. Take care to provide your plants with the right environment, and follow the tips presented here to protect your hibiscus from dieback disease.