Monday 18 February 2013

Pine Needle Scale on Spruce

If you look closely at the needles of your spruce tree and find tiny rice-like flecks of white on them you probably have pine needle scale, Phenecaspis penefolia.  This scale does attack pines, however it is most commonly found on white and Colorado blue spruce. Scots pine, lodge pole pine and Douglas fir are also affected by this pest. Damage can be as little as yellowed follliage, or if the population is high significant defoliation can occur.

The white armor scale cover on these insects looks like small flecks of paint on the host plants needles. You can see the white scale at most times of the year however the female scale may have already died leaving her empty or egg filled scale behind. Eggs are laid in the fall of the year and hatch in the spring of the following year. Eggs hatch in mid may around the time when lilacs are blooming; the crawlers then move to new needles where they insert there mouth pieces and begin sucking sap from the tree. Once they settle in the loose their appendages and start to secrete the waxy scale that will cover them for the rest of their life. Males may or may not be present.

The nymphs are spread from tree to tree by wind or birds. Eggs are laid under the scale by the females in the fall. Typically in northern areas there is one generation per year.

Verdant oil or registered chemical control must be applied when the crawlers are active and exposed. Typically this occurs early May to early June when the common lilac is in bloom. Crawlers will appear over a two to three week window of time so repeated applications of oil may be necessary. Another simple way to determine crawler emergence is to take several infested branches from your plant, put them in a well-sealed zipper bag and put it on your desk or shelf out of the sun. Check the bag daily and when the foliage appears to have fine orange dust or speck on it they have hatched. Again you will be a week ahead of the hatch in the outdoors as your office should be warmer than the woods.

I.S.A Certified Arborists are industry recognized experts in plant insect and diseases control. Contact your I.S.A. Certified Arborist to see if you have this damaging plant pest.