Cape plumbago (Plumbago auriculata) -- One of Grumpy's favorite sources for blue flowers!
Q: I live in South Florida and my cape plumbago and ficus hedge has been infested with white fly. There is a lot of dead wood on the underside of the plants and they are thinning out rapidly. I can't afford to replace them - I have over 130 feet of plumgago beds.
Thank you, George DeBarros
A: White flies are among the worst, most intractable of all garden pests. These insects multiply like crazy, spread from plant to plant, and are very hard to get rid of.
There -- feeling better?
Having said that, there is a a strategy you can follow to get them under control. It involves rotating the the use of a several different insecticides, which is necessary because white flies quickly build up resistance to any chemical that is used over and over again.
So do this:
1. Apply Ortho Systemic Insect Killer according to label directions. This product is absorbed through leaves and stems and kills sucking insects for several weeks. You can get this at most garden and home centers For more info about this product, click here:
2. A month later, apply a second systemic insecticide, called Bayer Advanced Tree and Shrub Insect Control. You mix this product with water and then use it to water your plants. It's absorbed by roots. It takes some time to start working, but when it does, usually lasts for an entire growing season. You can get it at most garden and home centers. For more info about it, click here and then on "products".
3. Once you get the white flies under control, monitor the situation by brushing the foliage with your hand from time to time. If any white flies are there, you should see them fly. Another sign of their presence is sticky honeydew and black mold on foliage and stems. If you see either of these signs, spray according to label directions with a third product, Oil Away horticultural oil, an organic pesticide made from refined cottonseed oil. You can order it from Gardens Alive!
After step 3, rotate use of the three products as you see evidence of the white flies. This should control them without leading to development of resistance. Do not spray if no white flies are present, as this is overkill.
For more expert and fascinating advice from Grumpy on how to care for cape plumbago, see "Curtains for Cape Plumbago?" by clicking here: grumpygardener.southernliving.com/grumpy_gardener/2008/05/curtains-for-ca.html