Question
We live in central NorthCarolina.  Have five buford hollies about 6'-8' high with a large scale infestation.  Started a weekly treatment with Bayer Complete Insect control, interspersed with Volck Oil #growing season ratio# plus Malathion.  Have pruned the lower branches with worst infestation and there is already new growth.  
Now is just past Labor Day and would like to know:
 a. Is treatment adequate?
 b. How long do I keep treating the bushes?
 c. How much can I prune and when should I stop to prevent winter kill on new growth?

Thanks for your help.

George
Greensboro, NC


Answer
Hi George,
Thanx for your question.  Holly scale are hard to control.  The best time to treat for them is when they are in the nymph or crawler stage in the summer time.  Here is a link from the University of Delaware that should be helpful.

http://ag.udel.edu/EXTENSION/horticulture/pdf/ent/ent-28.pdf

If the infestation is bad enough, you may want to do some drastic pruning if the current treatments aren't working.  Now that it is drawing towards autumn, the nymphs have probably already matured and settled into the adult-sucking stage and have grown their shells or coats.  More information about scales is shown in the reference below.

http://edis.ifas.ufl.edu/IN649

You pruned the worst off alread and you say there is new growth.  New plant growth or new scales?  If just new growth don't sweat it right now.  I wouldn't chemically treat anymore this year though.  Next summer start treating whether you see new evidence or not.  I hope this helps.
Tom