Cover Alberta Spruce for Winter?
Q: Hi . I bought two Dwarf Alberta Spruce trees last year. I covered them to protect them from winter kill, as it can get pretty cold here.
Now this spring all the needles turned brown and have fallen off. Is this normal? It's not just the inside needles it's ever single needle and the branches are brown. It looks like it's budding and will produce new growth.
Is this the dreaded spider mite and if so with what do I treat this with? I don't have a clue what horticulture oil is. Should I have not covered them for winter?
A: Dwarf Alberta spruces were discovered in, you guessed it, Alberta Canada, so they are capable of tolerating some cold weather.
You don't mention what you covered them with, so it's hard to say if this effected them, but it may have. If you used plastic or some other non-porous (non-breathable) material, it may have created a greenhouse effect and overheated the plants.
If you need to provide shelter, I would use a natural burlap, and I wouldn't necessarily cover them from head to toe (or root to top, as it were). You can create a wind barrier with burlap, and you can also apply an anti-transpirant in fall to help reduce the amount of moisture they lose during the winter.
It is still possible that you have had a run-in with spider mites, but if the plant is budding out all over you may be okay. Check for spider mites by slapping branches over a white sheet of paper, then looking for tiny specks to move around slowly. Smear the paper with the back of your hand, looking for greenish streaks.
Greenish streaks indicate bad guy spider mites, reddish streaks indicate predator (good guy) mites. If you have enough predators, they can handle a lot of the bad guys without our help.
Should you find mites, do not use horticultural oil as dwarf Albertas are sensitive to it.
Use only a registered miticide, and sparingly. Miticides will kill both good and bad mites, and the bad mites are capable of re-populating much faster than their predators, so you can actually be helping them by spraying too much (all the while thinking you're really killing them off).
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