Last updated on October 23rd, 2023 at 09:04 pm
Even experienced gardeners can find a disease or pathogen in their garden that they can’t identify or treat. White mold is one of those sneaky fungal diseases that can quietly strike and take over your plantings without notice. But what is white mold and what is its origin? We’ll explore some information about white mold and tips on how to identify and treat this silent but deadly disease for many plants.
What is white mold and where does it come from?
Fungal diseases come in all shapes and sizes, but white mold is one of the most common varieties affecting food and flower crops. In fact, it affects more than 400 plant species, with the greatest impact on economic crops.
The symptoms of white mold can mimic many types of diseases. Only when you get close and identify its mycelium can a confirmed diagnosis be made. And by then, it’s too late for that plant, and its neighbors may also be infected. Garden vegetables and many flowering annuals are often affected by white mold. What is white mold? Symptoms of white mold include leaf dieback, stem wilting and white fluffy growth on affected plant material. This develops into sclerotia, hard black, pencil-sized structures on diseased plant parts.
Over time, the plants die. White mold is most common in warm, humid conditions, especially when plants are crowded and have not been turned over. Sclerotia overwinter in the soil and reproduce in mild, moist weather. Sclerotia live in the soil for 5 years. Diseased spores can even come from a neighboring field. Other names for the disease are white canker, watery soft rot, wood rot, damping off, pink rot wilt, crown rot and several other descriptive names.
How to treat a plant affected by white mold
This fungal disease can be very difficult to treat, as the symptoms of white mold initially mimic many other plant problems. Once white mold is present in a garden, it usually appears every year, due to the spore’s ability to overwinter in fallen plant debris and soil.
Damaged flowers and plant tissue are often the first to be colonized by the disease. Spores are spread not only by wind, but also by insect activity and rain splash. Plant material left behind after the previous year’s harvest is often the source of the initial contaminants.
There is no approved treatment for white mold. Once a plant has the disease, you can try pruning the plant below the infected material and applying a fungicide. However, the success of this method is very limited unless the disease is detected very early. It is best to remove the plant and destroy it.
How can I prevent this fungal disease from occurring?
Since there is no effective treatment for white mold, it is best to try to prevent the disease. Experts on how to treat white mold suggest rotating crops and cleaning up plant debris from the previous season.
Use plants that grow upright rather than crawling on the ground and ensure good air circulation. Water thoroughly in the morning with soaked hoses or drip irrigation. Do not compost infected plants, as most composting situations do not heat up enough to kill the sclerotia. Instead of trying to find an effective white mold treatment, use resistant plants.
There are also biological controls available. The most common is one containing the fungus coniothyrium minitans. This is a natural control, but it is not registered in some countries for use.