Does your Sunpatiens look wilted? Does it seem like it’s rotting away? The culprit is a fungal infection due to soggy soil. Learn more about what causes this rot, how to treat it and what can heal your rotting flower.
What is this rot on my Sunpatiens ®?
Plants of the Impatiens family love water but they’re vulnerable to a host of water-related diseases. Hybrids like Sunpatiens ® are bred to resist, but extreme conditions can weaken the plant and trigger disease.
Downy mildew is a fungal disease responsible for killing entire beds of Impatiens recently, and Sunpatiens ® is resistant to the disease. However, other fungus that lead to root rot are still potent. They might threaten the plant’s survival.
Sunpatiens is vulnerable to two fungus: Pythium and Rhizoctonia.
Unfavorable conditions trigger these root rots:
- Heavy, clay soil
- Poor drainage
- High planting density
- Combination of summer heat and moisture
Note: if all seems lost, don’t despair! All you need is a single healthy-looking stem to start a new cutting!
Different types of Sunpatiens ® root rot
Both root rots, Pythium and Rhizoctonia, result from fungus contamination. The fungus is often already present in soil in a dormant state. When moisture and heat rise, the fungus looks for host plants. Wounds in roots are entry points. From there, it spreads through the plant. Both fungus cause root rot in other plants, such as this diseased vinca.
Symptoms of a Pythium infection on Sunpatiens
Black strands appear along stem and leaves. They’re clearly visible when a diseased stem is sliced open: black spots mark contaminated channels from health ones that convey sap and nutrients up and down the stem.
The plant starts rotting from the ground upwards.
Symptoms of a Rhizoctonia infection on Sunpatiens
The rotting starts at the crown or top of the Sunpatiens plant and then progresses downwards. The name for this is crown rot.
Sunpatiens leaves turn pale green and then yellow, always harboring a lot of moisture. They droop over as the structural integrity of the stem collapses.
Diseased cells accumulate and the plant disintegrates into a slimy mush.
How to treat a wilted, rotting Sunpatiens ®
In a nutshell: dry the root ball out, and control watering after that.
For infected Sunpatiens growing in pots
In pots, this is extremely rare, but if ever you recognize symptoms described above:
- avoid overwatering. Let soil dry down an inch deep (3 cm) before watering again
- increase drainage (repot with sand and organic matter)
- add a drainage layer at the bottom: clay pebbles or gravel
- check that the drainage hole isn’t clogged
- spray either a garlic decoction or fermented horsetail tea which are excellent organic fungus antidotes
Always use fresh soil mix for potted sunpatiens ®. Disinfect pots and tools with white vinegar beforehand, dry it off before planting.
For diseased Sunpatiens in a growing bed
If the ground is lower than surrounding areas, with heavy soil, your Sunpatiens risk root rot.
- Stop watering completely until soil has dried up to an inch/3 cm under the mulch.
Sweep mulch aside and press your finger to the ground: if dusty and dry, start watering again. However, if clumps of dirt stick to your finger, wait for a day or two.
Don’t worry about plants not getting enough water for now: they send roots deeper underground.
- if it’s raining a lot and you can’t control watering, remove all mulch for a couple weeks
- increase drainage: stab holes 8 to 10 inches deep along the growing bed
Ideally every 2 inches. Excess water seeps underground and air circulation around roots increases. A sturdy pencil can do the trick, but an iron or steel rod with a sharp tip is easier. It’s like aerating a lawn. Prevent spread of fungus by dipping gardening tools in 40+ proof alcohol between jabs.
- Cut rotted portions out.
If you want maximum protection, uproot sick plants entirely to protects nearby ones. Loosen soil up and remove the diseased plant out delicately to pull roots out instead of slicing through with a spade. This avoids open wounds in roots of healthy neighbors.
- Resume watering only when you notice wilting in other healthy plants.
- Treat against fungal diseases with natural solutions like fermented horsetail tea.
To be thorough, check with the nursery you purchased the plants from: perhaps other customers have the same problem, meaning the whole batch is infected.
How do I know if my soil is too wet for Sunpatiens ?
Mulch with wood chips hints to the answer:
- underground chips are black: high fungal anaerobic activity (rotting). Not necessarily evil, but it shows conditions are perfect for detrimental fungus.
- underground chips are brown/tan: healthy, aerobic activity, not prone to rotting
In extreme cases, roots appear above soil, weaving in and out of mulch. They’re reaching for air. Such soil types are full of water, and roots need to breathe as much as leaves do.
Preventing root rot and crown rot on Sunpatiens flowers
Fungal infections remain in soil for years. If you’re not able to improve the soil drastically, set up a raised garden bed. Indeed, a raised garden is a great way to reduce risk of root rot for all plants.
Another option is to find other plants that love wet, moist soil.
If you live in a mild climate (no frost or freezing), you can plant Sunpatiens again the following year. But if the weather gets cold spare yourself the effort and either sow green manure which will further enhance the clay soil or go for nice beautiful winter plants.