I've noticed a white chalky appearance on the tips of my mug pine. The pine looks otherwise healthy. is this an insect or a disease? I have other mugo pine bushes in other parts of my yard that do not have this chalky white appearance. I would appreciate any treatment recommendations if necessary. thank you
Hennepin County Minnesota
it may be white scale.
White residue on mugo pine is usually caused by an insect. The "white mold" is from pine scale, which is an insect that resides within the white scale. They feed on the fluids within the needle. They can become so numerous that the needles drop off prematurely leaving the shrub looking rather bare.
Your mugo can be treated with horticultural oil or an insecticide, however it is getting later in the spring to treat them. The best is in April when the eggs hatch and the young scale insects are in a "crawler stage" and are most susceptible to chemical control. I would suggest waiting until next spring to treat.