Nematodes are common plant pests. Begonia root knot nematodes are rare but can occur where un-sterile soil is used for the plants. Once a begonia plant has them, the visible portion of the plant will decline and could die. It can be hard to diagnose root knot nematodes on begonias because the problem starts under the soil. Luckily, preventing begonia nematodes is easy and starts at planting.
About Root Knot Nematodes on Begonias
Nematodes are the most numerous pests on our planet and unfortunate parasites to plant roots. They are non-segmented roundworms that occur wherever there is moisture. They are too small to see with the naked eye, which makes identification very difficult. Begonias with root knot nematodes are diagnosed from visual cues on the upper part of the plant. Usually, once symptoms are observed, it is too late to help the plant.
Root knot nematodes feed on plant roots and disrupt vascular system development, the plant’s carbohydrates and water. It is the juveniles that are the problem. These microscopic worms’ feeding behavior causes changes in the root, resulting in the formation of galls.
In order to detect their presence, it is necessary to dig up the plant and examine the roots. Both large and small roots will show round swollen sites. The entire root system will become stunted and shallow. As the feeding behavior causes more and more of the roots to distort, the plant’s entire system of translocation tissues is interrupted.
Diagnosing Begonias with Root Knot Nematodes
Outside of digging up the plant and examining the roots, there are cues on the surface that can help indicate nematode activity. The plant will appear to be suffering from lack of water, and indeed, it is, as nematodes interrupt the flow of moisture throughout the plant.
The foliage will exhibit chlorosis or yellowing and become limp and wilted. During hot weather and periods of dryness, the symptoms are most obvious. Plants that are in loose soil are more affected than those in good rich loam. In heavy infestations, the entire plant will decline, grow poorly, and can even die.
Preventing Begonia Nematodes
As with many diseases, prevention is the only sure-fire cure.
Never use garden soil to plant begonias, as it may be contaminated with nematodes. Use a sterile potting medium and scour pots to make sure they are free of any bits of previously used soil. You can also sterilize your soil with heat treatments. Nematodes are killed at temperatures of 104-130 degrees Fahrenheit (40-54 C.).
Disease symptoms are mitigated with good plant care, including feeding, adequate watering and minimizing any stresses like drought or exposure to cold. When purchasing plants, source them from a reputable nursery.