Fusarium circinatum is a fungal plant pathogen that causes the serious disease pitch canker on pine trees and Douglas firs (Pseudotsuga menziesii).

[1] Like other Fusarium species in the phylum Ascomycota, it is the asexual reproductive state of the fungus and has a teleomorph, Gibberella circinata.

[5] Because of the activation of systemic acquired resistance in native Monterey pine trees, however, the impacts of the disease in California have been mitigated.

The macroconidia are 3-septate, with slightly curved walls and the microconidia are single-celled, ovoid, and borne in false heads on aerial polyphialides.

The symptoms are similar to other damping off diseases with seedlings wilting and dying and exuding resin from the root collar areas.

[12] Host factors that can trigger infection include plant stress with excessive nitrogen in the soil, unbalanced watering cycles, warmer temperatures, and wounds from pruning or insect damage.

Due to the high tree mortality rate, reduced growth, and degradation of wood quality, the economic and ecological importance are greatly affected by this disease.

[13] The environmental interactions that take place to favor the spread and development of this disease play a large role in transmission.

Factors such as soil nutrient ratio, abiotic stressors, air pollution, temperature, and humidity can all contribute to the spread of this disease.

If timber had been a significant means of infection, the fungus would have spread more rapidly to other parts of the world as there is a considerable trade in pine.

Proper hygiene practices and surface sterilization are to be maintained throughout management, especially by preventing the accumulation of water nearby to deter increases in insect populations.

Susceptible Monterey pine trees that were repeatedly exposed to the pathogen gained resistance over time under controlled conditions, especially where the disease has been present for over 10 years.

Many countries are imposing quarantine controls on movement of propagating materials and this test can help prevent the introduction of the pathogen through contaminated seed.