What is onion rot? Treatment of Pythium Onion Root Rot

Onion pythium root rot is an unpleasant fungal disease that can live in the soil for long periods of time, waiting only for favourable conditions to take root and attack onion plants. Prevention is the best defense, because pythium onion root rot is difficult to control once it has started. What to do with Pythium Onion Rot? Read the following for advice.

About onion root rot

Pythium onion root rot can infect onion plants whenever the soil is wet for long periods of time, but it tends to be more severe in rainy weather when days are hot and nights are warm. The fungus also lives on plant debris and weed roots and can be spread by watering and splashing.

Onion seeds may be killed before germination or infection may appear a few weeks later. The disease also appears in other members of the allium family, such as leeks and garlic.

Symptoms of onion root pythium (thixag__6)

In the early stages of the disease, plants with onion pythium rot appear yellow and stunted. They often wilt during the day and recover at night. Eventually, water-soaked lesions develop on the stems and lower bulbs of onions. A watery rot appears on the roots, which may also turn black.

Onion root rot control

Plant the onions in well-drained soil. Consider planting onions in raised beds, which can minimize the impact of disease. Similarly, consider growing onions in pots filled with commercial potting soil.

Dispose of infected plants in sealed bags or containers. Never put infected plant material in the compost.

Keep the planting area clean and free of plant debris. Control weeds, as pythium rot can live in the roots of weeds.

Do not use excess nitrogen fertilizer. Nitrogen causes lush, tender growth that is more susceptible to infection.

Fungicides can be effective when applied every two or three weeks, or whenever rainfall continues for more than two days. Look for products that are registered for use against pythium onion root rot.
Use fungicides only when necessary; the pathogen may become resistant.

Clean the soles of your shoes after walking on infected soil. Thoroughly clean tools after working in infected areas.