Spruce Spider Mite - Nursery IPM

**Spruce Spider Mite (Oligonychus ununguis)**

Eggs are brown, round, flattened and have a thread sticking up fromtheir center
Growth from larvae to adult happens in about a month
Adults are ½ mm in length, varying from brown to dark green in color, with salmon pink colored legs
3-4, but up to 10 generations can occur per year, depending on conditions
When temperature is too hot, SSM enters a dormancy period until it becomes cooler in the fall
Wind is main dispersal mechanism
Leaves behind tiny strands of webbing on the needles of host plants
Can lead to damage, dropping needles and a reddish-brown tint
Early signs of infestation include a stippled yellow color on the upper surface of host needles
Prefer older needles over new ones, on the lower inner branches of the tree
Can cause sudden damage as reproduction quickly occurs
Host plants: Ornamental landscape conifers
- Can be present in natural forests

Natural predators: phytoseiid mites, spiders, some beetles, lacewings
Pests are less active in hot, dry weather
Simulated rainfall on Fraser fir seedlings significantly limits spruce spider mite populations
Reduce plant stress
Syringing, or spraying infested foliage with a heavy water stream, may help to dislodge the mites and reduce infestation severity.
Tap branches over white paper to scout for presence

Contact insecticides:
- Avermectins [6]: Abamectin
- Pyrethroids [3]: –thrins, Tau-fluvalinate
- METI acaricides and insecticides [21A]: Fenazaquin
- Spinosyns [5]: Spinosad
Systemic insecticides:
- Tetronics [23]: Spirotetramat
- Organophosphates [1B]: Malathion, Acephate
Considerations:
- Will harm beneficial and non-target species.