Anyone knows what this is and how to prevent it?

[stig]

While trimming all the yew hedges at the castle today, we noticed large dead areas in some of them.
I'm thinking it is fungal, maybe something like fusarium, but this is not my area of expertice.

Is anyone ( Willie, maybe?) familiar with this and knows what does one do to prevent it.

It is European yew Taxus baccata

 

[Burnham]

I don't know about the die-back...but I spy a hard working young lady.

 

[stig]

That one got uploaded by mistake.
The owners of the castle were so impressed with the way she workes, that they offered her a part time job after school and in weekends doing odd stuff around the place.
Good for her. It is almost impossible for teenagers to find jobs here, because of the bad economy.

 

[Marc-Antoine]

We had the exact same thread on the french forum, for a Leilandii hedge though.
The OP was firstly on a red spiders attack, but it ended rather to be fungal.
Phytophtora and Pestalotiopsis funerea were named but it was only a guess.

Treatment proposed: spraying with a systemic fungicide like Aliette or myclobutanil (protect yourself).

 

[gf beranek]

Damping off of new growth? Appears fungal indeed.

 

[sotc]

Prune off some of the dead limbs and examine them for insect damage, then peel the bark back and look for staining in the cambium. First guess around here is usually spider mites. A colored piece of paper held under an area of good and bad tissue, shaken hard of the paper and then examined for tiny moving specs usually tells that tale. Especially if you recently had a temperature spike

 

[stig]

Willie, I was doubtful about the mites, because of the cold wet weather we've had all summer, but you nailed it in one!

Got about 20 of the little buggers on the paper first try.

So tomorrow we'll spray all the hedges with insecticide.

Any recommendations, or will any of the stuff normally used for aphids work?

For preventive spraying next year, when would be to optimal time.

Before or after the buds break, or even later?

 

[Paul B]

red spider mites are mites, no insects. Need a miticide rather than an insecticide although some products do both. We used to have Kelthane but I think only Sulphur is still registered here for use on spider mites. I believe pyrthrum extracts are effective but total coverage is important as it breaks down in sunlight fairly quickly.

 

[stig]

We use synthetic pyrethricine ( spelling?) on aphids in x-mas trees, so I usually have some on hand.

But now that you mention it, sulphur is used on mites in abies Normanniana x-mas trees, so I guess I can pick some of that up, and use it to exterminate them.

 

[FJR]

There are also different miticides for different stages of the life cycle. Forbid (spiromesifen) is effective for all stages, which helps make things less complicated. Spider mites are also a reflection of plant stress, so maybe you could help them create a healthier environment for the Yew's and not have to worry about miticide's in the future.

 

[stig]

I just checked and none of the spiromesifen products are legal here, so it'll have to be sulphur.

I already suggested we fertilize the yew hedges, since some parts are very pale and seem like they lack nitrogen.
That has been ok'ed by the management. We can get some fertilizer, mainly used for roses, that releases nitrogen rather slowly.
I plan on using that, since I don't want to have it leach out and fertilize the grass below the hedges. It is a bitch to cut on the slopes, and it would look silly with a brim of bright green grass under each hedge, when the rest of it is yellowish.


One cute thing I forgot to mention.

When we did the colored paper/shake the branches test and all those mites landed on the paper, my apprentice, Martin, spontaneously said:" Damn, it is fun to learn new stuff like this!"

 

[gf beranek]

Good investigative work, Stig. You nailed it!

 

[Paul B]

Stig, if you use a pyrethrum (I spelled it wrong in the first place) based product consider using one with piperonyl butoxide in it. It isnt organic but it acts as a synergist to the pyrethrum and extends its half life. I believe horticultural mineral oil is also somewhat effective, not poisonous per se but physically detrimental as it can clog the parts that the insects and/or mites breathe with (spiracles)

 

[sotc]

Theres lots of products you can use. Some are strictly adults, some are juvenile and some do it all. I currently use an adulticide where I have to do 2 applications 2 weeks apart. Cost me $330 a quart but it goes a long ways. Glad it worked out for you

 

[Tucker943]

Hort oils or soaps should do it no?

 

[sotc]

As long as the label says so, just don't spray them on blue trees

 

[treelooker]

more thinning cuts and less shearing may also make it healthier. most hedges also like to be sloped downward so the bottom part gets more light.