Floridian OB advice needed for scale

[orchids44]

I have a problem from time to time with scale...and now is one of them
What product do you find most effective to kill scale? Do you rotate with other products?
Thanks

[silken]

For me the only that gets rid of them completely is Merit which has the active ingredient imidacloprid. I believe in the U.S. there is a Bayer product for roses that has it as well. It is a systemic so it gets into the plant and kills scale and other insects for an ongoing period. The trouble with non systemics is you can rub off and kill existing ones but then eggs hatch and the scale can hide in very hard to see places. I clean off any visible ones, then spray with Malathion to get any I missed and let it run into cracks and crevices of the plant. That gets the situation under control immediately and then I treat with the Merit. It will take a while to enter the plant's system so you may have go after newly hatched ones for several weeks. I have been told some or all Dendrobiums do not like it but I have treated Cattleyas, Oncids and Phals with no problem to the plant.

[tucker85]

I think every orchid collection in Florida has some scale. The advice that Silken gave you is a good aggressive type of treatment. If there's only a little bit of scale, I use a toothbrush and some insecticide soap to remove it. You don't need to remove the scale from the pot, dislodging it from the plant will kill it. Insecticide soap is not a poison. It's a soap high in potassium that destroys the insects protective waxy coating. I spray the pseudobulbs with the soap and then brush with the toothbrush until all the scale is off. While you're at it, remove all the papery sarongs that cover the outside of the pseudobulbs. Scale often hides under them. Check the plant in a week, and treat it again if there's any sign of new scale. This process has been very effective for me.

[james mickelso]

Excellent advice Tucker. The dried sheaths are where they hide and keep coming back. Take those off and it becomes easier. Soap smothers the little buggers as well as the eggs if you don't wash it off when watering.