Rufous milkcap

The Rufous milkcap (Lactarius rufus) is a basidiomycete fungus primarily known for its mycorrhizal associations with forest trees. In the context of forestry and nursery management, it is classified as a biotic factor that can influence the growth dynamics and nutrient uptake of young seedlings, sometimes creating competitive conditions in the root zone.

As a biological agent, it colonizes the roots of host plants through specialized mycelial structures. While often symbiotic, its over-proliferation in soil can shift the balance of the rhizosphere, potentially impacting the development of sensitive nursery stock by monopolizing soil moisture and specific nutrients intended for tree seedlings.

Common host species susceptible to its presence include Pinus sylvestris and Picea abies. Signs of its activity include the appearance of fruiting bodies near the trunk base and a visible network of white mycelial cords in the upper soil layers. Seedlings affected by high fungal density may exhibit stunted growth or yellowish foliage due to nutrient uptake competition.

Development conditions require cool, moist environments with acidic soil pH, typically ranging between 3.5 and 5.5. The fungus thrives in areas with high organic matter content, particularly needle litter. Optimal mycelial growth occurs during periods of high humidity and moderate temperatures, facilitating the rapid spread of spores.

Strategies for protection and control focus on altering the environment to discourage fungal growth:

• Implementing systematic soil aeration through regular tillage.
• Managing irrigation to prevent excessive soil moisture in nurseries.
• Applying balanced fertilization programs to support host plant vigor.
• Removing excessive needle litter to reduce available substrates for fungal colonization.