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
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
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?
- posted 13 years ago