Hansen, (1929) Pyrenochaeta terrestris is a fungal plant pathogen that infects maize, sweet potatoes, and strawberries.
[1] P. terrestris is also known to infect shallots, garlic, leeks, chives, cantaloupe, carrots, cauliflower, cowpea, cucumbers, eggplants, lima beans, millet, oats, peas, peppers, potatoes, spinach, sugarcane, and tomatoes.
If the fungus grows on wheat straw or cellulose, it produces a pink pigment that is a prominent characteristic of the resultant disease.
[3] P. terrestris is adapted to temperate, sub-temperate, and tropical climates due to its ability to survive in a broad range of pH, temperatures, and soil types.
The fungus will extend throughout the root system, but the pathogen does not infect the basal stem plate or scales of the bulb.
[1] Plants infected early in the season develop a poor root system that cannot keep up with water uptake during hot temperatures; this results in great yield loss.
Planting cultivars of onion that are resistant to the P. terrestris pathogen is a very effective management strategy that can be used in all commercial operations.
This method has shown to be effective in areas like the San Joaquin Valley, where onions are planted in fall after a summer fallow period.