Question
I've just come home from one night away and found my wisteria half dead. I've had a close look and found lots of the new wisteria scale all over it. I've picked loads off and sprayed with mild soapy water. What should I do now ? I live in the Buckingham area and the plant is about 5 years old but not that big.

Answer
Hi Tracy:
Scale insects can be a real "pain". They make their living by sucking the plant juices from the plant. There are several effective insecticides out there, but timing your spray(s) are very important to catch this critter at its most vulnerable stage of development- the babies or "crawlers". One option is a horticultural oil- this one "smothers" the babies.  It can damage your plant if you use it when it is 80 degrees or hotter. Check with your local garden center for the most appropriate material to use and when.  Another good insecticide that is available in the US is a product by Bayer called BAYER ADVANCED TREE AND SHRUB INSECT CONTROL. It is a liquid that is mixed with water and applied to the soil- roots take it up.  It contains a chemical called Imidachloropid- a common insecticide.

Hope this helps

Steve