Double trouble

ParisGirl · Jun 26, 2008

It looks like I have a double infestation on my hemlocks: Wooly adelgid and scales.

I noticed white woolly deposits on some young sprigs, and brough one inside to look under magnifier glass, and check on the internet for what it is. The white deposits are not restricted to the stem, they are mostly on the back of needles... so I kept reading, and found out about scales. Looked more carefully, and saw the little elongated crawlers...

The infestation is small, I could easily spary the branches. I live in Massachusetts.

Help! What do I do to save my plants? What should I use?

BTW, my rodhodendrums have some sort of scales also, white and sticky. I sprayed oils on the stems, and poured systemic insecticide in the ground, following all instructions. They are still there, white and sticky, after 3 weeks. Are my hemlocks afflicted by the same pest?

Anyone would help with some advice?

Thanks

Brush Hog · Jun 26, 2008

Horticultural Oil will take care of the adelgids and scale. Your rhody might have cottony camellia scale. Can be treated with hort. oil or acephate pro 75. I'm just learning insect and disease so someone more seasoned will chime in I'm sure. Good luck
Pete

woodville · Jun 26, 2008

Oil works great on both. Spray the rhody now and spray the hemlock and the rhody again in the fall. You really have to drench both insects for control.

Ed Roland · Jul 2, 2008

Paris,

Wooly adelgids are nasty. According to the entomologist at BTRL in Charlotte, NC. it only takes 4 adelgids located on one inch of the stem to shut down all new growth on that stem. Control is important.

BUT, It is not enough to eradicate pest populations. You must identify the primary cause of stress. When trees are stressed they become predisposed to infection.

You can load these trees up with systemic chemicals and cover the foliage with hort oil but the insects will return if the tree is unhealthy. Know that healthy trees can produce defensive chemicals that deter insect feeding. These chemicals take too much energy to detoxify or are even harmful to the insect to ingest. Look into optimum cultural practices along with reasonable insecticide use.

ParisGirl · Jul 5, 2008

the source

Thank you all for the answers; very helpful.

I found out the source for the infestation: my neighbor has a horrible hemlock blight infestation on his hemlocks... He will not be able to spray (they are taller than his 2 floors+attic house), and in fact does not seem interested in doing anything.

Will I have to pour systemic every year to protect mine?

thanks

woodville · Jul 6, 2008

Not at all. When I said you really have to drench them in my last post I meant really saturating them in oil. It does not matter around here if your trees are healthily or if your neighborhood has Adelgid or not. Odds are if it's a hemlock sooner or later you will see Adelgid if you within the 128 belt. Scale on the Rhody is more of a seasonal occurrence, some humid wet springs seem to coincide with scale outbreaks. Either way a good soaking of oil in the fall will help both. Hell for the scale you can hit it with a garden hose or use a car wash brush with mild dish soap on the stems and get great results now before the sooty mold kicks in. I would hold off on the oil on the hemlocks this time of year.