Marks on Olive Leaves

nadaud_1981(Zone 4)September 28, 2012

Hi there. I tried posting this to the Tree Forum, but in the end they recommended that I try the Houseplant section instead. I purchased an olive tree (Olea europaea) from a local nursery a few weeks ago, and it is doing magnificently. But I have noticed that one or two of the leaves have these sort of tiny indentations, or pits, about half the size of a pinhead on their undersides. They are very tiny, and barely noticeable; I'm not sure if they would even show up on a photo. The pits themselves are the same color as the undersides of the leaf. When I shine a flashlight through the back of these leaves, I see a lot of tiny black or brown dots, presumably where the indentations are. It should be noted that I just removed a scale insect from one of the branches, but I'm not sure if these are just wounds from that, or a fungal attack. The humidity in here is very low, and I only water when the soil is nearly dry. The tree also receives adequate air circulation, and the lowest temps in my apartment right now are about 70 degrees. I am unable to post any pictures, as I do not own a camera at this time, but any help would be appreciated. Thank you.

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Could you take a leaf to the nursery and ask them? If it wasn't a big box store you may get an intelligent response. Without pics it may be difficult to identify the problem, if it is one.

    Bookmark   September 28, 2012 at 9:16AM
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Nadaud...I checked leaves, front and back on my Olea, but didn't notice what you're describing.

Since your plant had Scale, for the time being I'd shower/hose foliage with soapy water then rinse..spray thoroughly.
Wait a couple days to see if the dots reappear on each leaf. If more dots are present, more than likely your Olea still has scale. Hopefully, it doesn't.

As for indentations/pits, I haven't a clue, unless leaves are deformed where scale sucked those areas. Insects, especially heavy infestations cause leaf deformity. Toni

    Bookmark   September 28, 2012 at 11:26AM
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nadaud_1981(Zone 4)

Thanks for the suggestions. I have been spraying the plant with a pesticide, and the scale that I did remove was already dead, so that is good. I got up this morning and noticed fewer dots than a few days ago, so it could be that it just needs some time to heal; almost every plant I've bought from the nurseries around here had some sort of problem, usually from pests.

    Bookmark   September 29, 2012 at 10:33AM
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Nadaud. I hope you rid those scale.

What type of pesticide do you use? Is it chemical?

Nadaud. I learned this trick from a Citrus seller in Fl, and most grateful to her.

Ever hear of Fish Emulsion? FE is an organic fertilizer, but also kills scale, doesn't harm/burn leaves.

I add 1 capful per 16oz sprayer of water. This ratio is for more than one plant, but can be divided.

FE works like a charm. I'd never, ever use anything else to prevent or kill scale.

I spray plants w/FE twice a year as a preventative. Once in spring, then in autumn before hauling plants indoors.

My Olive tree, purchased 1999, was scale-packed. Since the package arrived at night, I didn't notice insects, so placed between two citrus.

While misting, I saw brown lumps on its leaves. After closer inspection, discovered lumps were SCALE. Two citrus branches nearest the olive were also infested.

I phoned the citrus seller to ask the exact amount of FE and water.

After spraying olive and citrus, within two days, scale were gone, and thank God, never reappeared. I sprayed a second application a week later to make sure those critters would stay away.

Spraying and re-spraying with chemicals is too much. Maybe I'm prejudice since I dislike and don't use chemical insecticides...espeically on edibles.

The only problem is, FE has a fishy odor. Smell lasts a couple days, but the odor is not harmful, like chemicals. There is an odor-less type, but I've never used it, so don't know if it's truly odor-free.

Anyway, just wanted you to know you had another option.

Good luck..keep us posted. Does your tree have olives? If so, do you know what to do before eating them? Toni

    Bookmark   September 29, 2012 at 12:06PM
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nadaud_1981(Zone 4)

I use a pesticide called "Triple Action Plus" Don't know if you have it in your area, but you could always Google it and let me know what you think. The name is because it is a Miticide, Fungicide, and Insecticide. I've noticed that you don't want to even breathe in the fumes, so I bought a $30 respirator from a local hardware store for when I spray.

My tree doesn't have olives yet, and it is only about 10 or 11 inches tall still...but it is growing fast. I know to pickle the olives before eating them, but I'll have to look into that some more when the times comes. I'll probably just give them to my mom; I don't really like the taste of olives :)

    Bookmark   September 29, 2012 at 1:40PM
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rhizo_1 (North AL) zone 7

Your triple action is a combination of neem oil (not harmful to breathe) and pyrethrin. Don't use inside if you have any pets, especially cats.

It's probably overkill for your purposes.

    Bookmark   September 29, 2012 at 2:45PM
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nadaud_1981(Zone 4)

Interesting. The pyrethrin is also dangerous to fish; fortunately, I have no pets.
I read someone on here saying that you should start with the most ecologically safe pest controls, and work your way down if problems continue. This probably isn't the safest stuff around, but it seems to do the job. It also has piperonyl butoxide in it, which works to make the pyrethrin more potent. Airborne piperonyl is toxic to fetuses; i.e., pregnant women shouldn't use this particular pesticide, either. Apparently, the effects are similar to lead exposure.

    Bookmark   September 29, 2012 at 5:22PM
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