White spots on Western juniper

In the spirit of identifying white dots on bonsai these past few weeks, today’s subject is Western juniper.

Western juniper

For those unfamiliar with the variety, Western junipers are frequently covered with white dots, one per scale. On some occasions, the dots enlarge and merge together to form a sticky white mass.

Sticky white substance on Western juniper foliage

Unlike the white dots caused by the various insects we’ve looked at recently, the white on Western juniper is a resin secreted by the foliage. Working on Western juniper can quickly lead to dirty, sticky fingers, but the resin is natural and not a sign of infestation.

Resin build-up on Western juniper foliage

Sometimes this resin turns black. This can be either dust sticking to the white resin or a non-harmful fungus that grows on juniper foliage. As this fungus doesn’t do well where I live, I most often see it on newly collected junipers.

There’s nothing to do about the resin as it’s natural. I’ve come to appreciate it over time as one of the “charms” of the variety – a variety best known for great movement and deadwood.

So as not to turn completely away from bugs today, do read Michael Hagedorn’s recent post on wood-boring beetles if you haven’t – it’s a good read about a pernicious pest.