White pines (Pinus strobus) make wonderful additions to the home garden with room for their extreme height and rapid growth rate. However, these trees are vulnerable to root rot fungal infections that threaten to severely damage or kill your white pines. Get to know the types of symptoms to look for as well as how to manage a problem that arises for a vigorous home landscape.
Well-maintained, vigorous white pines have a greater potential for fighting off or avoiding fungal infections that lead to root rot than pines in distress or decline. Grow your white pine trees in locations that offer full sun, according to the Clemson University Extension. White pines thrive in moist, well-drained soil with good fertility.
Annosus root rot is one of the fungal infections that attacks white pine trees. Caused by the fungal pathogen Heterobasidion annosum, this problem infects trees through openings like wounds. Phytophthora root rot is another problem affecting white pines, caused by the fungal pathogen Phytophthora cinnamomi, according to the NC State University Cooperative Extension Service. This soil-borne disease thrives in warm, moist conditions and invades through tree roots.
Annosus root rot of white pines results in needles that change to a red hue, sparse crown foliage due to leaf drop, fungal growths near the base of the tree, stringy decayed roots and, in severe cases, tree death, according to the NC State University Cooperative Extension Service. Phytophthora root rot of white pines leads to stunted foliage and cone development, thinning of crown foliage, yellowing of needles, decay of roots and eventual plant death.
Choose hardwood trees instead of white pine if an annosus infection has occured. Remove trees that are infected or dead; if you choose to prune or cut down your tree without removing the roots, apply dry granular borax to the surface of stumps to prevent further disease spread, according to the NC State University Cooperative Extension Service. For phytophthora infection of white pines, if your tree dies, replant a loblolly pine if you must select a pine, as it is a more resistant species.
Though there is no recommended chemical control method for annosus root rot in white pines, chemicals may assist a phytophthora fungal problem. Apply a fungicide with the active ingredient mefenoxam to the soil within up to a 30 square foot area around the white pine tree, according to the NC State University Cooperative Extension Service. Fungicides will not cure your white pine but will lessen the severity of infection and reduce the spread of pathogens.