Trichodorus minor

Systematic position and nature of the pathogen
Trichodorus minor is a plant-parasitic nematode belonging to the phylum Nematoda, class Enoplea, and order Triplonchida. Known as a stubby root nematode, it is an ectoparasite that lives in the soil rhizosphere. Unlike endoparasites, it feeds externally on root tips using a specialized feeding structure called an onchiostyle, which it uses to puncture plant cells.

Diseases and host crops
This nematode has a very broad host range, causing damage to many economically important crops such as potatoes, onions, tomatoes, corn, and sugar beets. Beyond the direct damage to root tissues, Trichodorus minor is economically significant as the primary vector for the Tobacco Rattle Virus (TRV), which induces serious internal necrosis and stunt symptoms in tubers and foliage.

Biology and life cycle
The life cycle of the stubby root nematode is completed entirely in the soil. It progresses through egg, four larval stages, and adult stages. Because the entire cycle occurs in the soil, the nematode is highly sensitive to soil texture and moisture levels. They can persist in the soil for long periods even in the absence of a host, making them resilient in diverse agricultural environments.

Environmental conditions and damage
The species thrives in sandy and sandy-loam soils where mobility is high. The feeding process inhibits root cell division, leading to stunted, thickened, and often "stubby" root systems.

• Reduction in root system mass and efficiency
• Stunted plant growth and yield losses
• Increased susceptibility to secondary pathogens
• Transmission of damaging viruses like TRV

Control and management measures
Management of Trichodorus minor is challenging due to its presence deep in the soil profile. Cultural practices such as crop rotation, maintaining weed-free fields, and the use of resistant varieties are foundational strategies. In high-value greenhouse systems, soil fumigation or the application of specialized nematicides is often required to minimize the risk of virus outbreaks. Effective management relies on regular soil testing to determine population densities before planting susceptible crops.