Brown needles and silky web in hemlock

#5
I didn't notice any stippling on the needles themselves, if that's what you're meaning. How are the the brown needle clumps produced - do the [spiders, mites, spidermites???] kill the needles (by sucking or chewing on them)? or do they just gather them (and the cause of needle browning and drop is different)?
 

JD3000

Well-Known Member
#6
I fugured the shed needles were from seasonal needle drop and they just stuck to the silk.
Hard to say from a pic but there could be some other critter I'm not familiar with or some minor foliar fungal issue.
 
#7
Is mite damage a serious enough problem to warrant treatment? Perhaps it depends on the degree to which there's mite damage. If it is affecting >50% of the branches, what treatment do you guys use?
 

JD3000

Well-Known Member
#8
Abamectin is inexpensive but nasty stuff.

Floramite and Hexygon have low toxicity and minimal impact on beneficials.

Forbid works wonderfully but is expensive.

Soaps, oils, neem oil.
 
#9
Horticultural oil at 2% will take care of your mites and adelgid. What rate did you apply the imidacloprid at?
Keep in mind yearly applications of imidacloprid are not necessary to control adelgid. I've seen mite outbreaks from yearly apps.
1 app at .2 oz. per inch of dbh should give you at least 5 years of control for adelgid.
 
#10
Great information. Thank you all!

I believe we used Zenith 75 WSP at 3.2 oz/gal.
How fast does the hort oil affect the mites? Is it important to spray both the upper and lower parts of the needles?
 
#12
Great information. Thank you all!

I believe we used Zenith 75 WSP at 3.2 oz/gal.
How fast does the hort oil affect the mites? Is it important to spray both the upper and lower parts of the needles?
Foliar apps of Zenieth 75wsp are labeled at 1 pack (1.6 oz.) per 300 gallons. I would go back and check your mix rate. If you are using it that high that would explain the mite outbreak.
Hort oil will kill mites on contact but has no residual effect. Coverage is essential to good control.
 
#14
Check how many oz. you're using per inch and get back to us. I don't do premix solutions with imidacloprid it's to easy to over dose. .2 oz per inch of dbh is where you want to be.
 
#15
I believe we did 1 packet (1.6oz) in a gallon of water to treat dbh of 24 inches, which equates to 0.067 oz/inch. Perhaps we're way to low and should be treated dbh of 8 inches with the same 1 gallon solution? Label appears to indicate 0.1-0.2 oz/inch range, so 1 packet should treat 8-16 inches DBH?
 
#17
Yes, one pack treats 8" of dbh for most insects.
Flat headed bores like eab and bbb on trees over 15" dbh should get the high rate of .4 Oz per inch.
 
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