Pratylenchus

Pratylenchus is a genus of tiny worms known as lesion nematodes. These small creatures live inside plant roots and can cause damage to many kinds of plants, especially in cooler parts of the world. Unlike some other nematodes that stay in one spot, lesion nematodes move around as they feed and grow inside the roots.

They mainly eat the softer parts of the root, called the cortex, which can weaken the plant and make it harder for the plant to grow strong. Scientists identify different species of Pratylenchus by looking closely at special parts of their bodies, such as their mouth tools called stylets. These nematodes are important for scientists to study because they can affect crops and other plants, helping us learn how to protect them.

Hosts and symptoms

Root lesion nematodes can infect many different plants. For example, Pratylenchus penetrans can affect over 350 types of plants, including important crops like soybeans, potatoes, corn, bananas, and wheat. These nematodes often cause damage to the roots, creating dark, dead areas called necrotic lesions. These lesions can let harmful bacteria and fungi enter the plant, leading to more disease.

Above ground, infected plants may grow more slowly, appear pale or chlorotic, and may wilt. Sometimes whole areas of a crop field can look patchy because some plants are healthier than others. This can lead to lower amounts of food being produced, which is why farmers watch for these problems.

Environment

Pratylenchus nematodes are affected by soil conditions such as moisture, minerals, temperature, and pH. They are often found in sandy soils and areas with weed infestations. These nematodes can survive in many different environments but prefer moist, temperate soils for breeding and moving underground. In very dry conditions, they stay inactive until moisture returns and plants start growing again. They become most active when soil temperatures rise above 68 °F (20 °C).

Management

One way to manage lesion nematodes is by using soil fumigation and nematicides. However, this method isn’t always effective and can be costly. Another option is water immersion, where infected plants are placed in a hot water bath for about 30 minutes to remove the nematodes without harming the plant. This has worked well for P. coffeae.

Crop rotation can also help reduce nematodes in the soil, as different plants are affected by different Pratylenchus species. Choosing resistant plant varieties and cultivars is another useful strategy. This is the only current way to control P. vulnus.

Life cycle and pathology

Female lesion nematodes lay single eggs either inside plant roots or in the soil around them. They can produce fertile eggs without needing males, a process known as parthenogenesis. In many species of these nematodes, males are very uncommon.