Factors affecting germination, mycoparasitism, and survival of Sporidesmium sclerotivorum

Area of Science:

• Mycology
• Plant Pathology
• Biological Control

Background:

• Sporidesmium sclerotivorum is a mycoparasite of Sclerotinia species.
• Understanding its germination and infection dynamics is crucial for developing biocontrol strategies.

Purpose of the Study:

• To investigate the germination and parasitic cultivation of Sporidesmium sclerotivorum on Sclerotinia sclerotia.
• To determine optimal conditions for conidia production and survival of the mycoparasite.

Main Methods:

• Germination assays in soil and on membrane filters.
• Optimization of cultivation conditions including pH, temperature, and substrate amendments.
• Assessment of conidia production, infection rates, and long-term viability.

Main Results:

• Macroconidia germination occurred within 3 days and increased with time and sclerotia concentration, up to 9 mm distance.
• Optimal germination and parasitic growth were observed at pH 5-7 and 25°C in quartz sand with 1-2% sclerotia and 0.07% CaCO3.
• 100% sclerotia infection was achieved in 5 weeks, leading to logarithmic conidia increase (3-4 x 10^5 conidia/g).
• Sporidesmium sclerotivorum showed reduced viability in air-dried sand cultures but remained viable in air-dried soil for 15 months.

Conclusions:

• Sporidesmium sclerotivorum demonstrates efficient germination and infection of Sclerotinia sclerotia under specific soil conditions.
• Optimized cultivation parameters can enhance conidia production for potential biocontrol formulations.
• The mycoparasite exhibits significant survival in various soil conditions, indicating its potential for field application.