Mugo pines are short, round almost scrub-like pines that produce bushy clusters of needles and branches. Browning at the tips of the branches indicates a health problem that may stem from one source or a combination of factors, including the growing environment, pests and disease problems. Proper care of mugo pines helps restore their health.
Excess fertiliser around the base of a mugo pine tree contributes to a condition known as fertiliser burn, which causes brown or yellow edges on the branches of the tree. Commercial and synthetic fertilisers contain salts and other agents that dry out the soil and damage the roots, especially if more fertiliser is applied than the tree needs to grow. Fertiliser burn has the potential to limit the growth of the mugo pine during the spring and summer.
According to the University of Illinois Extension website, mugo pines are sensitive to both drought and oedema. Drought occurs when mugo pines go too long without water; although the trees are hardy and stand up to dry soil well, prolonged drought causes browning of the ends of the pine's branches. Oedema is a condition caused by standing water in the soil, which leads to dead roots and browning or yellowing branches as the mugo pine drowns.
Mugo pine trees are susceptible to two fungal diseases that cause browning at the ends of branches, including dothistroma needle blight, which causes branches and needles to turn reddish brown, often beginning at the lower portions of the mugo pine tree. Sphaeropsis tip blight causes mugo pine branches to turn brown at the ends, in addition to causing the formation of cankers along the branches, which sometimes girdle and kill the branches. Fungicides and good cultural care help control fungal diseases.
According to the University of Illinois Extension website, scale insects and sawflies are common pest problems of the mugo pine tree. These pests contribute to problems with brown or yellow needles at the ends of mugo pine branches. Pests feed on the sap in the mugo pine, which weakens the tree and prevents it from processing nutrients correctly, leading to discolouration of the needles. Apply a pesticide spray beginning in the early spring to help control problems with pests on mugo pines.