Obscure scale

[treevet]

Anyone have any strategy for Obscure scale? They are hard to hit in crawler, hidden under dead scale after they settle or in second nymphal stage due to protective wax secretion. Interesting that this pest is not an issue in forests I read.

I was thinking of injecting immidacloprid but would rather not inject. Even my huge front oak has it (picture). We have had 2 major droughts here that have aide the outbreak IMO.

Don't these things just build up and up and never diminish? They have a few natural predators but not of much effect I do not think.

I feel the injections cause dieback and eventually when the dead tissue coalesces then access and availability of stored carbs are way diminished?

 

[Ed Roland]

Distance 8oz per 100 gal +oil .5 gal on active crawlers early june to early august is my strategy.

As a hard scale I believe it will be resistant to merit.

 

[treevet]

Thanks.

They list it in the Mauget book under Immicide but like I said, I'd rather not inject, esp. my own tree.

 

[John Paul Sanborn]

Metasystox out of a Kioritz gun will knock anything down Icky-poo nasty stuff

 

[D Mc]

Don't forget imidicloprid can be applied as a drench as well (Bayer Advanced Garden Tree& Shrub Insect /control Concentrate).

I would rather see you determine the cultural cause of this infestation and mitigate those circumstances if at all possible.


Dave

 

[treevet]

We have had droughts and last year a major drought and 2 consecutive years of the hottest temperatures in weather record history I see as the impetus Dave.

As for the dormant miscible oil and other sprays, Dan, I sold my 60 and 35 gpm Beans and got out of the spraying bus. Guess I could sub it out but just was looking for success stories of alternatives, esp. systemics.

I think it is difficult to read control other than by squashing the old scale and see if live ones are under them. Also you would see healthier terminal growth I guess.

 

[NYCHA FORESTER]

Phloem feeder or a xylem feeder?

Merit does not "readily" move into the phloem so targeting a phloem feeder with a material the "stays" in the xylem may not be the best choice.

 

[treeseer]

My baldcypress was caked with armored scale one year and poof all gone the next.

Birds? Bees? terpenes?

 

[treevet]

Phloem feeder or a xylem feeder?

Merit does not "readily" move into the phloem so targeting a phloem feeder with a material the "stays" in the xylem may not be the best choice.

That makes sense NF, but why then does a phloem feeder like the larval stage of EAB die when an ash is treated (injected) with Merrit (Immidacloprid)?

It is one of the 2 best treatments/preventatives according to researchers.

 

[treevet]

My baldcypress was caked with armored scale one year and poof all gone the next.

Birds? Bees? terpenes?

Yes likely predators. But I think this scale is particularly insidious in that it cakes up and live crawlers settle under encrusted dead bodies of others gaining protection where they can feed safely away from predators and chemicals and maybe even suffocation from arboricultural oils since they do not have a long residual.

 

[treevet]

There were no crawlers at oil spray time.

I don't spray these days but when I did.....we would stagger the DO spraying year to year based on degree days. Our goal was to cover the range of variability in the ramping up of the scales metabolism. Our goal was to spray as late as possible to catch metabolism high.....but before phytotoxicity to swelling buds and bud break was a problem.

We had great success controlling both obscure and oyster shell scale mostly on landscape planted pin oaks that were 25 to 60 years old.

I too did much spraying back in the day. I was just musing about the 70's and Gypsy Moth in NJ and you didn't go down a street and not see a spray rig shooting 90 feet up into the oaks etc. Trees were sprayed virtually every day from DO on to leaf drop.

I cannot recall seeing one tree co. spraying any trees in the last 2 years around here on one property. You see a rig going down the road from time to time but rarely.

Lawyers have way too much power.

 

[Upidstay]

I would say hit it good and hard with imidichloprid. If you can't spray it yourself, what other option do you have? Personally i would deep root inject it. Mix in a mycorhizal inocculant too. Merit will not wipe out the critters, but it will knock them back to a manageable level. The myco inocculant will help the tree weather the storm, fight it off on its own.

 

[NYCHA FORESTER]

That makes sense NF, but why then does a phloem feeder like the larval stage of EAB die when an ash is treated (injected) with Merrit (Immidacloprid)?

It is one of the 2 best treatments/preventatives according to researchers.

They are not only eating the phloem but also eating the cambium. If you see gallaries in/on the xylem then you know they are getting a "Belly-full" there too. If the Scales probosis makes it all the way into that cambium region then certainly there is a good chance they will get wacked.

 

[Ed Roland]

I would say hit it good and hard with imidichloprid. If you can't spray it yourself, what other option do you have? Personally i would deep root inject it. Mix in a mycorhizal inocculant too. Merit will not wipe out the critters, but it will knock them back to a manageable level. The myco inocculant will help the tree weather the storm, fight it off on its own.

It has been my understanding that armored scales (Family Diaspididae) can not be controlled with merit/imidacloprid. Bio controls include some species of wasp parasitoids, a mite predator, and three species of lady beetles.
Dormant oil and distance may not preserve these critters if they come in contact with the chemical but the residual is not all that long. Seems to be a sensible approach if timed correctly.
Some of the other systemics may be an option.

 

[Urban Forester]

It has been my understanding that armored scales (Family Diaspididae) can not be controlled with merit/imidacloprid...

True, we stopped using merit for "hard" scales 4 years ago, as control was non-existent. As with alot of products lately, scale control is most often listed as "crawler" control. Even oil w/soft scale has drawbacks.

 

[treevet]

Blatant false advertising by Mauget then. Nothing new in this biz tho. All bout the $.

 

[pcarborist]

I've heard Safari works well on hard scale (along with dormant oil before April).

Safari. Safari is a product available from Valent U.S.A. Corporation; it contains the active ingredient dinotefuran. Safari is formulated as a SG with 20-percent active ingredient. The product is labeled for control of aphids, whiteflies, leafminers, mealybugs, scales (both soft and hard), fungus gnats and thrips. Safari can be applied as a foliar spray, drench or through chemigation. The active ingredient is very water soluble, which means it is rapidly taken-up and distributed throughout the plant. Dinotefuran is another neonicotinoid-based insecticide with the same mode of action as imidacloprid (Marathon), acetamiprid (TriStar), thiamethoxam (Flagship) and clothianidin (Celero). The rates for foliar applications are 4-8 oz. per 100 gal., whereas the drench application rates are 12-24 oz. per 100 gal.

 

[elmtree]

I've heard Safari works well on hard scale (along with dormant oil before April).

I had success in 2007 with Safari treating a maple with hard scale. It was a drench method if you would like I can give you the date, air temperature, DBH, and the amount used. I got the idea from Mat at Midwest arborist supplies. But I don't think the label claims to treat scale this way.