For those regular readers of RGO you may remember that I have been battling the nasties over the year. The mealies have been gone now for over a year and my phals really improved. I can't say it's because they aren't being dragged down by mealies or whether its the change in fertilizer to the MSU formulation from Ray. In either case I have the best looking an branching spikes I've every had in my collection. Thanks Ray and Enstar II!
The Enstar took out the hard brown scale that was around a few of the plants. I don't think it was much of an infestation but I did have problems with it on a couple of the Oncidiums and Encyclia. I haven't seen hard scale in over a year now. I don't miss popping those hard shells like bubble wrap.
The real war was with the soft scale. I tried all the contact stuff from the bottle, malathion, orthene, Enstar II, and other stinky stuff. It would knock them down but they would just pop up somewhere else. It was like a game of wack-a-mole in the arcade.
Last summer I bought the Bayer Advanced Tree & Shrub Insect Control Concentrate. At first I didn't do my arithmetic correctly and was applying it at a reduced rate and didn't see any affect. After returning to the calculator I realized my mistake and I applied it at a rate of 1 oz per gallon through the dos-a-matic injection system. I did this for three consecutive weeks of watering in August.
Since this is a systemic and must be sucked up by the roots of the plant I thought three weeks of application would insure that the plants carried the insecticide throughout the entire plant. According to the label when used on trees and shrubs it is effective for an entire year. In October I thought I saw another outbreak of scale and applied another application but have decided that I only saw eggs hatching.
The eggs of the scale seem to last many months. Five months after application I do not find any live adult scale. On the older growths and deep in the sheaths I do find crawlers. When I find them I clean them up immediately.
My hypothesis is that the eggs were unaffected by the drenching with the Bayer solution. Those eggs hatch where they were hidden on the older growths. The crawlers start out looking for a place to start sucking and get the residual of the poison still pulsing through the plant. They seem to swarm form a mound about 1/2 of an inch across. I haven't found any scale on new growths just on aging older canes and pseudobulbs.
In my previous attempts I was able to kill the live scale but a couple of months later the eggs would hatch and soon infest the collection. With the systemic in the plant over a longer period these eggs hatch but have nothing to eat and soon die. The older growths did not suck up the systemic insecticide as well as the new growths. The new growth has a higher concentration of insecticide so if the crawler was blown into one of the new growths it is quickly poisoned.
Any thoughts about this from the more experienced grower who have won the battle of the scale?
Good Growing, Gene