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Discussion in 'Problems, Pests, & Diseases' started by justagirlart, Jul 12, 2019.
What can be used to kill scale on Phrags?
The best product will be a systemic, since the adults are quite well protected from topical treatments by their shells, while they suck the juices out of the plant.
My preference is acephate.
FYI - Acephate is highly toxic to bees.
If you only have a few plants, repeated scrubbing with a soft brush and soapy water may do the job. If you have a substantial collection, acephate is better. Careful where you spray it (and it stinks, too).
orthene, which is a drench, is very effective on
scale. However, it is destructive to insects in
general. Unless you have a contained area like
a greenhouse, don't use it. Yeah, it stinks.
If its a few plants, use 91% alcohol on a paper towel. If its many you need a spray.
We use a solution of Dr. Bronner's peppermint soap, Neem Oil, alcohol, water, and for the kicker Merit 75.
BTW, we have about 200 Phrags and know a little about growing them.
Thank you. I am jealous. All I have is a starter kit of 20. Love them. They are my favorite orchid.
Does a horticultural grade of oil work on scale, too? A local grower mentioned this recently, but did not say if it would work on paphs / phrags.
yes, but as it is a suffocant, it is necessary to get appropriate coverage
sometimes the crawlers are down in the leaves and not easy to get
I would caution you to try out whatever you use on only one or two plants to see if there is any adverse reaction to the plant. On one occasion I used Safer Soap to get rid of aphids on an Epidendrumm and the whole plant just wilted and died - it was a softer-leaved Epi. Also the temperature should be not be too warm if you use oil spray. Softer-leaved plants seem to be more sensitive.
I used to be a big proponent of oils, but have backed off because the "bang" is minimal and the "buck" is quickly consumed by the damage they can do to the plants.
Consider Azamax - it is a concentrated form of azadirachtin, the active ingredient in neem oil, without the oil. It is a contact and systemic insecticide and miticide and, unlike most, does affect eggs and juveniles in addition to adults.
I don't know anything about Azamax, but I love the name of the stuff. I think I'm going to try to find it locally.
I have been battling white scale for a number of years now, but not mostly on Phrag. It has been difficult to deal with. My latest attempt is an insect growth regulator called Enstar. It has a good reputation, but it also is quite expensive (may see if any other members of my local orchid society need any, as it also comes in quantities that should last a lifetime). I was a little amused to see that insect growth regulators are also used in anti-flea medications and home treatments (don't ask).
Hydroponics shops often carry it, but Amazon might be the easiest source...
Boisduval scale can be VERY difficult to eradicate.
I had an outbreak once, and the only way I was able to get rid of it once and for all was to make a blend of acephate, imidicloprid and kinoprene (Enstar), and soak the entire greenhouse - plants, media, structure - three times at one-week intervals.
Well, Ray, that was very ambitious of you! I just finished by 3rd weekly general spray, although I did not drench the pots or the greenhouse, and only used Enstar with acephate. Actually, I have seen no bugs since the first spraying (and that includes mealies). I'll now wait a month, and inspect every plant individually. IF anything comes back, I'll probably drench the plant at that point. There are, of course, a couple of the systemics that come in the form of surface mini-pellets, including imidicloprid, which they would also get. I remain concerned about the root-dwelling mealies.
Since I've just been fighting dog fleas, it's interesting that both the topicals put on the dog as well as the professional house treatments include insect growth regulators--some the same ones we use on plants.
With an IGR or not, I'd not stop now and wait a month.
Neither product is 100% effective, so there will always be survivors that either were missed by the treatment or managed to be less- or unaffected, so waiting gives them the opportunity to reproduce. That is exactly how resistant strains are developed.
Tristar was recommended to me and I’ve done 2 sprays, 7 days apart spraying foliage and pots/mix thoroughly. Was planning one more spray at same interval. Are you saying more than 3 sprays is needed? Also, since I’m only spraying 5 plants, can I keep the mixed spray from week to week or do I need to remix each time? I’m keeping the leftover cool and dark.
No, the general recommendation is to do three treatments at the recommended intervals, then if the infestation resurfaces, do three more using a pesticide with a different mode-of-action (MOA).
Generally speaking, the recommendation is to NOT store diluted pesticides, but I believe that is primarily a safety measure. Folks rarely label their application devices, so it's possible to end up with a container of an unknown substance. A week or two is probably fine, but I'd put a piece of duct tape on the sprayer and use a marker to ID it, the dilution, and the date, and you should be good to go.
BTW, scale on Phrags is not common. ??? Wipe them all off and then treat with chemicals, soaps and oils.
Southernbelle, was Tristar effective? Ray, I only stopped a month after 3 weekly sprayings of a combination of acephate and Enstar. I'm in that period now. Next month I will inspect each plant. I'd rather not do more general spraying, if it's not needed. If I find infestation at that point, Ray, what would you recommend next. Enstar and something else? I'm also inclined at that point to isolate any plants with infestation and only treat those, or throw some or all away. I'm aware of the possibility that they will achieve resistance, if they haven't already.
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