flechers scale on Taxus

[John Paul Sanborn]

I've got a infestation leves that pass the economic threshold.

I'm bringing someone in to do Metasystox (ick!) soil injections next week for the adults and am soaping the foliage every 4 months starting today.

This is taking place on 3 different cvs throughout the 13 acre campus. Different sight charicteristics as far as hydraulogy and lighting. the pH is consistantly high though.

No place is over irrigated and some heavy infestations have no irrigation. Past waether the past few years had consistant low rainfall for extended periods. This year we are well above annual rainfalls (some rivers are still over a foot above flood stage).

Insecticde use the past few years has been minimal to nill.

DOes anyone gave an idea as to why there would be such high populations on these plants?

 

[Guy Meilleur]

Originally posted by John Paul Sanborn
DOes anyone gave an idea as to why there would be such high populations on these plants?

Pure guesswork from afar:

Lack of natural enemies. Other stressors besides moisture.

The Johnson/Lyon book: "All of the eggs hatch within a short time (now in WI?), making the motile crawlers easy to control with one application..." If you're soaping today you may get em the first time. What good will soaping do 4 months from now? What need is there to call in the toxic artillery until you see if soap crashes the population? Sounds costly in $ and enviro.
The book does not say how long the adults live, but is sounds like the young ones do the damage.

Has previous lack of control been due to timing? Can you see em crawling? page 99 has awesome pictures, really helps to know what to look for.

 

[John Paul Sanborn]

Another source said there is a 3 week hatch window.

The motile stage causes leaf discoloration and sooty mildew, it is the high populations of adults that are sucking the life out of the plants. Right now you can pick out the worst infestations by looking for stunted yellow branches, those will have several scales per twig. Two weeks ago, some were gooey and some had egg masses under them (For those not familiar, the adult dies after laying the eggs to protect them. Most scale are parthenogenic).

Oops, I ment every 4 weeks for the next few months, just to be sure. Since i could not find when the motile stage stops. I need to wate till the end of the year to get the Johnson et al companion set.


This is from U.IL

Applications should be made in mid-June when crawlers are active or when hills of snow hydrangea are in full bloom because the early crawlers are most susceptible to insecticides.

From forestry img-adults

The reason for using the nasty stuff is because we've past the economic threshold and need to kill the adults befor we loose enire plants. I've had to prune out sections already.

Drought stress is the only thing I can think of allowing the infestation levels. There have been no past treatments for anything. My gardener thought some of them were just growing slow due to light and water issues.

 

[Guy Meilleur]

Originally posted by John Paul Sanborn
I need to wate till the end of the year to get the Johnson et al companion set.

Sorry to hear you're without that basic resource. Still, what you're finding for free looks to be consistent with it. And thanks for the "parthenogenic" tip. If they reproduce without sex (poor creatures), then they only live one year, right?

Let us know if you find out the cause; I'm seeing a lot more scale here than I used to (but then I'm looking more too)