Juniper Scale

DESCRIPTION
Tiny (1.5 mm) greyish-white round discs on needles and twigs. They move very slowly or not at all.

DAMAGE
Juniper scales suck sap from juniper foliage, causing plants to initially look off in colour. As the infestation progresses individual branches will turn grey or yellow, drop needles and produce little new growth. Finally, large portions or the entire plant will die.

LIFE CYCLE
Scales overwinter as full grown fertilized females. Each female lays up to 40 eggs in May, which hatch over a 30 day period from late May to late June. Crawlers disperse over the whole plant and begin feeding. They are light enough even to be blown by wind to other junipers. Crawlers develop rapidly with females molting 3 times and males 5 times. In late summer and early fall tiny winged adult males seek out and mate with adult females. There is only one generation per year.

CONTROLS
• Apply dormant oil and lime sulfur in March to kill overwintering females.
• Inspect junipers regularly for scale.
• Prune off and destroy badly infested branches.
• Apply pesticides thoroughly. Juniper scale are protected by armoured shells, making control difficult.
• Infested plants should be removed and replaced with a species other than juniper.

PESTICIDES
• Chemical-Latox at label rate, once in late May and again in late June.
• Alternative-Safer’s Soap or Trounce at label rate, first in late May, again in mid-June and finally in early July.
• Summer Horticultural Oil in early June. (to print, right-click on this page)