Mushy stems on Plants

Symptoms

Soft stem bases are one of the signs of this problem, and they usually point to overwatering. Infected tissue turns brown, becomes mushy, and develops an unpleasant odor. Stem cankers or rots that are soft and mushy sometimes come with that same odor.

Stem tissue near the soil line turns brown and deteriorates, and cankers form on the stems. Under wet conditions, brownish masses of bacteria exude from the infected tissue. Bacterial soft rots affect many plants, including begonia, carnation, daffodil, geranium, impatiens, and zinnia.

The roots can turn brown, soft or rotted below ground. Off-color roots range from brownish to blackish, especially at the root tips. Aboveground parts of the plant yellow, droop, wilt, and die. Root rot is often associated with poor drainage and overwatering.

Brown, soft tissue appears in both the stems and the roots. A plant with a soft stem base plus yellowing, drooping, and wilting growth matches the pattern described here. Cankers and mushy rots on the stem are part of that same pattern.

Causes

Overwatering is one cause of mushy stems, and soft stem bases usually are indicative of it. Poor drainage is another, and root rot is often associated with poor drainage and overwatering. Bacteria are involved in soft rots, which turn infected tissue brown and mushy with an unpleasant odor.

Infection can also enter through wounds or injuries on the plant. High soil salt levels are another listed cause. Warm, damp conditions combined with heavy fertilization can also bring the problem on. Potting media that is aging and losing drainage can cause it too.

You can think of these causes in a few groups. Some come from how you water, such as overwatering and poor drainage. Others come from the soil or potting mix, such as high salt levels and aging media with declining drainage. Wounds or injuries are a separate kind of cause, and so is heavy fertilization in warm, damp conditions.

Root rot, with roots that turn brown, soft or rotted, is the condition tied to poor drainage and overwatering.

Diagnosis

Start at the stem base, where softness usually is indicative of overwatering. Next, look at the tissue near the soil line, which turns brown and deteriorates when this problem is present. Mushy tissue that also has an unpleasant odor fits soft rot, where bacteria cause the infected tissue to turn brown and soft.

Then check for cankers on the stems and for brownish masses of bacteria, which exude from infected tissue under wet conditions. Examine the roots too, because roots that turn brown, soft or rotted are among the symptoms. Off-color roots that look brownish to blackish, especially at the root tips, are another sign.

Then think about the conditions the plant has been in. Ask whether the soil stays wet, whether the pot or bed drains poorly, and whether the potting media has aged. Also ask whether the plant has wounds or injuries, salty soil, or heavy fertilization in warm, damp conditions.

Aboveground parts that yellow, droop, wilt, and die add to the picture. The next section covers what to do.

Treatments

Every treatment in the facts is cultural, meaning it changes how you grow and handle the plant. Remove infected plants immediately. Discard infected plants, since pesticide sprays are not effective once pathogens are distributed through the plant. Disinfect pruning tools in 70% alcohol after removing infected material. Avoid splashing water, contaminated hands, and unclean pruning tools.

Do not overwater, and avoid overhead irrigation. Keep foliage dry and provide good air circulation. Provide good soil aeration and drainage, along with an appropriate watering frequency. Soft stem bases usually are indicative of overwatering, so the watering advice here applies directly. Root rot is often associated with poor drainage and overwatering, and good soil aeration and drainage are part of the treatment.

Use a combination of sparse watering and low fertilization. Heavy fertilization in warm, damp conditions is a listed cause, and low fertilization is part of the treatment. Ensure proper water quality, and leach the container soil periodically. High soil salt levels are a listed cause, and periodic leaching of container soil is a listed treatment.

Infection can enter through wounds or injuries, and clean hands and clean tools are part of the treatment list. Use disease-free cuttings, corms, and other planting stock. Seek information on resistant cultivars and consider planting them. These steps apply to plants this problem affects, such as begonia, carnation, daffodil, geranium, impatiens, and zinnia.

Prevention

Prevention starts with the conditions the plant grows in. Provide good soil aeration and drainage, with an appropriate watering frequency. Avoid overhead irrigation, keep foliage dry, and give the plant good air circulation.

Overwatering and poor drainage are both listed causes of mushy stems. In containers, ensure proper water quality and leach the soil periodically. Use a combination of sparse watering and low fertilization, since warm, damp conditions combined with heavy fertilization are a listed cause. Aging potting media with declining drainage is also a listed cause.

Start with disease-free cuttings, corms, and other planting stock. Seek out resistant cultivars and consider planting them. Avoid splashing water, contaminated hands, and unclean pruning tools, and disinfect tools in 70% alcohol after removing infected material.

Plants most often affected

Bacterial soft rots affect many plants, including begonia, carnation, daffodil, geranium, impatiens, and zinnia. Lilac, dahlia, hyacinth, and chrysanthemum are also among the plants listed for this problem. If you grow any of these ten plants, soft stem bases and brown, mushy tissue are worth watching for.

No plant page in this build records this problem yet.