WHITE SPRUCE LOSING NEEDLES ON NEW HEALTHY GROWTHS.

Asked July 5, 2018, 6:36 PM EDT

I have a white spruce tree I picked near the ridge line on the top of the world highway back in 2003. I have had it growing in a large pot (14 inch diameter) at my residence in Anchorage for the past 15 years and the tree itself is is about 45 inches tall. This summer it grew lush, robust new growths. However just this week (early July) most of the new growths shed their healthy green needles. I am not sure why. Some of the new growths - perhaps 30% still retain their healthy look. Please advise what may be causing this problem.

Anchorage Alaska spruce

12 Responses

This is a mystery to me as well. I'm assuming it has been watered well?

Dear Stephen. Thanks for your reply. Yes, the plant is well watered in well drained soil. The plant was also fed with plant food since the beginning of the growing season and subsequently all new growth were healthy and robust. The sheding of needles was sudden with no disclouration. I have attached some photos for your reference. Please note, the shedding needles are primarily on the new growths. The older growths have nearly been effected (as of yet) any ideas? Regards/adam


I suspect this a form of needle rust. I would apply a fungicide that contains chlorothalonil as an active ingredient. Be sure to follow the label directions.

Dear Stephen. Thanks for your reply. I am to assume the pathogen is in the soil. Will this fungicide also kill the "good" fungi in the soil as well, or is this more targeted toward a specific type of fungus?

Spruce needle rust has a very complex life cycle that includes over-wintering in the Labrador Tea plant. I don't pretend to understand it.

This fungicide is usually applied to the tree and needles without contact to the soil. Even if it does come into contact with the soil, I would not worry about it hurting the beneficial fungi. If I am not mistaken, I believe spruce has a symbiotic relationship with ectomychorrizae. You run a greater risk of hurting the mychorrizae with high concentrations of chemical fertilizers.

Dear Stephen, Thanks again for your advice and clarifying what needs to be done. The fungicide is to be applied topically. I will look for some on my next day off at one of the specialized gardening stores nearby. Cheers/Adam

Dear Stephen, I do have one more question. Would it be advisable to prune the denuded branches of the tree for both therapeutic and aesthetic sake? would this help or hinder the recovery. It is my understanding spruce trees do not grow new needles. Not sure how pruning works with spruce trees. Thanks again for your advice. Cheers/Adam

I think pruning back the dead material makes a lot of sense.

Dear Stephen, I recently purchased the fungicide containing chlorothalonil and applied it via spray bottle to the entire tree. I still see needles dropping and some changing to a brown colour (hence the name needle rust). Should I apply another dose? also, even though this is a topical application I am wondering if the fungus is soil born or something which grows on the foliage itself and not visible to the naked eye. Please advise. Thanks again. Adam

Dear Stephen, I recently purchased the fungicide containing chlorothalonil and applied it via spray bottle to the entire tree. I still see needles dropping and some changing to a brown colour (hence the name needle rust). Should I apply another dose? also, even though this is a topical application I am wondering if the fungus is soil born or something which grows on the foliage itself and not visible to the naked eye. Please advise. Thanks again. Adam

Dear Stephen, I recently purchased the fungicide containing chlorothalonil and applied it via spray bottle to the entire tree. I still see needles dropping and some changing to a brown colour (hence the name needle rust). Should I apply another dose? also, even though this is a topical application I am wondering if the fungus is soil born or something which grows on the foliage itself and not visible to the naked eye. Please advise. Thanks again. Adam

I would re-apply as soon as the label directions say you can.