Last year my little lemon trees were attacked. A trip to the local nursery with a trimming in a zip lock bag got me a diagnosis and a bottle of spray. I had to spray weekly and seemed to just keep the critters at bay. They went away for the winter but now are back.
Anyone have any recommendations for a solution? What I was using last year was a spray for scale by "Safer" brand for fruit and vegetables. One tree lost quite a few leaves and I'm thinking I need something a bit more effective.
Certainly there are stronger insecticides. Some are systemic (absorbed by the plant) and work well on scale BUT, if you (or others) ever consume the lemons from those trees, you don't want that! The spray you used before may have worked but the trees just got infested again. The reason for the repeated sprayings is that the adult scales are not killed easily. The adults just finish their life cycle and die off as they always do. The spray is to kill the new young ones before they get their protective shell. If you are too late with a spray, some will mature and survive. You might try an oil spray. Oil smothers the scale and can even smother most of the adults. You'll still want to spray a few times. I have experience with killing scale but I live a thousand miles from the nearest outdoor lemon tree. I would think a light oil such as ... wait a minute, I'll run down to the basement and find out for sure ... Yes, my bottle of "SunSpray Ultra-fine" oil IS labeled for killing scale on lemon trees. That might be a really good choice.
over here we us an oil spray called 'white oil' (it's a petrolium bi-product a like product)available not sure could be wrong here but i think you call it dormant oil, but any good nursery will be able help you with the product name. best applied after the heat of the sun has gone for the day, you might need 2 or 3 sprays.
also look for ants they and the scale share a symbiotic relationship, so if you find ants then you need to move them along so you don't get reinfested.
there is a recipe for a homemade version of the oil on my remedies page.
Read the label before you buy. I believe products labeled as dormant oil are for use on trees while they are dormant. It might be used on an apple or plum tree in the early spring just before the leaves start to grow. I doubt that it is labeled for, or safe for, use on trees with leaves. Some formulations might be. Read.
I had to look up a picture of San Pedro cactus to see if it was covered with spines or not. I see there is space between the rows of spines. If you have it in a pot, and it's not too huge, you can do it the easy way. Take some rubbing alcohol on a cotton swab and rub off every scale. Spray, or otherwise wet the plant with alcohol about twice a week to kill the microscopic young ones. Inspect the plant closely every week for a while to watch for new scale. Get them before they have time to reproduce. If you live where you are growing this cactus outside, you'll probably have to spray with something stronger.
il Sun, 13 Feb 2005 10:40:17 -0500, Steve ha scritto:
Do you have any idea how much alcohol one can use on any plant before it turns up it's toes? I get occassional scale on various plants and some can be rubbed off but the bay tree is loaded (mainly on the trunks, not the leaves.
It's in the greenhouse... That's what has me worried! I've used some sevin', but have read that it usually takes an oil based insecticide to effectively kill adult scale? But what are oil based pesticides and how dangerous are they?
I have some doubt about what they mean by oil based insecticide. Some insecticides are wettable powders to be mixed with water. Some in liquid form are also water based. Some liquid insecticides are in an oil base (you still usually mix that liquid with water). More often, these are referred to as petroleum based insecticides. These can be harsh on delicate plants. I wouldn't think cactus would be delicate but I'm not sure. If you burn a few leaves on a plant that can grow new leaves, that's one thing but if you burn your cactus, it's scared for life. They may have simply been referring to products like the "SunSpray Ultra-fine" oil that I mentioned in my first post in this thread.
I'm pretty sure most plants can tolerate undiluted rubbing alcohol (usually, it's isopropyl alcohol) sprayed as often as you want. It evaporates fast and leaves no residue. Alcohol will not kill adult scale. It's mainly to kill the newly hatched babies. On a plant with too many scales to remove by hand, I would use something else. The proper type of oil will smother even the adults without harming the plant and it's quite non toxic.
il Sun, 13 Feb 2005 14:50:12 -0600, Katra ha scritto:
Oil based, because they effectively suffocate the insect. That's why Conqueror Oil is mineral oil, (think baby oil) not a pesticide. But added with Orthene® (aephate) gives better results. [so the manufacturer says] but Orthene thins stone fruits and seems to be added for mealey bug. So any plain mineral oil will be safe up to harvest time. But I guess you don't want to eat the cactus. Just make sure anything you buy tells you what's in it.
Hmmmmm... I wonder if I mixed pennyroyal essential oil with some vegatable based oil to act as a diluent? Scale as adults are sessile, so those breeders I need to kill. :-P I can put the oil spray into a spray oil dispenser used for cooking. AKA an "oil pump"
I'm finally getting pennyroyal established in one of my raised beds. Great ground cover and acts as "green mulch" and is insect repellant.
D'you think this might work?
I have a small investment tied up in the San Pedros as landscaping cacti and have been actively trying to propagate them. This damned scale infestation could be a real blow!
I'm not planning on eating the San Pedro, well, maybe the fruit, but future customers might so I do have to be careful! They are primarily a landscaping cacti and, as I posted earlier, I'm trying to propagate them. I have 20 successful cuttings growing off of 3 large 3 branched ones I paid $75.00 each for. They ain't cheap!
Actually, I've not lost a good cutting yet. They need to be a minimum of
3" thick to survive. 5" to 6" do even better. I plan to re-trim stumps for more buds as I remove the buds ready for callusing and re-planting.
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of my tip cuttings came down with scale and it had spread to the two adjacent pots before I discovered it. :-( I've sprayed liquid sevin all over the others and my cycad and finally cleaned off all three plants by hand. The spines are short so I could do it!
The biodensity in Greenhouse #1 might need to be reduced until I kill all the buggers. I don't know where it came from!!! I did those cuttings about 3 months ago and the appearance of the scale was rather sudden! :-P
Oh yes... One reason I'd rather attempt making my own.
At least the sevin biodegrades, but I used it before I'd read that carbamyl (sp?) is not very effective against sessile scale...
I also do not wish to kill my greenhouse spiders. I have a kite spider living in Greenhouse #2 that has been there for several months. That greenhouse is clean tho'. No mealy bugs or scale.
Here she is:
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is a bitty little thing, but effective at keeping moths and gnats at bay! :-)
Ok, I just did not know if anyone had any experience with pennyroyal. I know it sure works for fleas, and tends to keep slugs and stuff out of the gardens where it is growing!
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