Spruce - end needles dropping

[ATH]

Looked at a few spruce trees that were treated last fall forbspruce spider mites. The outer needles are falling off of some of the branches now while the inner needles are looking OK. Any thoughts?

 

[Jed1124]

Wow ok this is interesting. I had a sample that I submitted for the exact same issue to the ag station last week. Good healthy blue spruce that I treated last year for Rhizospheara. Client called and said it was losing needles. I went to the residence to do an inspections and all needle loss was from last years terminal growth. Sent samples to the ag station because I was stumped. Ag station called me last week and they had no answers. Very interesting.
Looked identical to what you have.

 

[ATH]

Odd. I was there Friday afternoon so didn't take samples to send yet...I like to send those on a Monday or Tuesday to make sure they are fresh.

 

[Jed1124]

I have to call the client on Monday. I was starting to lean toward some sort of abiotic condition. Most needle loss was at 3ft or so. Perhaps a ride on lawn mower exhaust? I'm stumped at this point. Did you do the mite treatment on the tree in question?

 

[ATH]

Yes...treated 6 trees early last fall...in 2 groups of 3. 2 trees - 1 in each group is now symptomatic. One has the browsing needles and a few bare branches. The other has more bare branches, but no browning needles that remain. The spots are peppered throughout the lower several feet of the tree. Not bad...but is it going to get worse???

We had a pretty mild winter. Some dry periods but not droughty. So I don't think I can blame it in weather.

 

[Dbodave]

I saw a ton of needle rust last year. Not treatable and seldom occurs 2 years in a row.
We never spray for mites.
http://www.extension.umn.edu/garden...e-tree-diseases/spruce-needle-rust/index.html

 

[Jed1124]

I saw a ton of needle rust last year. Not treatable and seldom occurs 2 years in a row.
We never spray for mites.
http://www.extension.umn.edu/garden...e-tree-diseases/spruce-needle-rust/index.html

That's a good call and something I did not think of. I also saw a lot of needle rust last year. I was under the impression that needle rust affected last years growth but according to your fact sheet I guess I was wrong. The needles in question are tan/pink in my samples. Funny that my local plant pathology department did not pick up on any spore inoculate though.
Why no mite treatments? They can have a pretty big impact on many conifers.

 

[Dbodave]

It's my companies philosophy that by spraying mites you run the risk of making the problem worse by taking out predators. That's what I was told. Do you see improvement in tree health after the mite treatments? That's the main criteria we have for our treatments. We do quite a bit of needlecast and a few adelgid treatments, but the spruce trees still need to be in reasonably decent condition before we make recommendations. Once they've thinned out beyond a certain point it's difficult improve health or appearance, so we try to be honest to our clients about expectations.

 

[Jed1124]

That's a good point. With so many generations mites can become resistant fast. If I test for mites and the white paper is crawling I will do an application. Bronzing on Arborvitae can be corrected within a year. A lot of times interior needle loss on Spruce is due to mites and not needle cast. I like using Forbid. It's expensive but resistance is low and you get a nice 40 day residual. As far as treating for needle cast, it's all about preventative and not curative. I am frank with clients in that they are looking at 3-5 years of treatments before the tree puts on enough new growth to fill in.
When your in for the long haul being open and honest about expectations is the best sell you have.

 

[ATH]

Spruce needle rust and spruce bud worm were really the only things that I could find that take out current year needles. But neither fit. There are no spores...I looked microscopically to confirm. The browning needles that are still there do have the described "tan to pinkish" cast...but with no fungal spores, I don't think it is spruce needle rust. Certainly appreciate the link.

 

[Dbodave]

Sure thing, it could be something new. I've heard of a couple new diseases out there like sudden needle drop, but that affects inner needles. Keep us posted if you find out.

 

[ATH]

Results from lab: Phomopsis. (and Rhizosphaera)

 

[Dbodave]

Results from lab: Phomopsis. (and Rhizosphaera)

Thanks, I've seen the same thing quite alot recently.