Where Do Red Spider Mites Come From?

duartix

I mean, who puts them in my trees? Other insects? There are no birds in my balcony...

Can the eggs be dormant all winter and then bud like mad when the heat comes?

How is it possible to have a few localized infestations last Summer, which I washed away several times and now this Spring they come up in a totally diferent tree?

Can anyone name a few brands of insecticidal soap (preferably comercialized in Europe) that will get me rid of these pests at least for a few months?

I'm afraid to go on vacation for more than a week in the Summer, because last year they almost defoliated one of my most promising bonsai.

Thanks in advance for your help.

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RonMartin(deceased)

Almost anything can bring them in. They are pretty good hitch-hikers. A leaf blown by the wind. A new plant brought in that was infested with them. Even you. They take a ride on your clothes when you are outside walking and then follow you home.
Sneaky little buggers they are.
No hiding from them

Ralph

I think the greater question is why are you having infestations? If you know the why, and correct it, maybe no more infestations.
Mite infestations are generally a sign that the tree(s) are in some kind of stress. While bonsai is stress all by itself, you may want to ask yourself the following: do you have trees that require full sun in partially shaded areas? Is the area not open enough to get good air flow? What about the watering situation? To much, to little?
In my area people will see severe mite infestations on junipers that are not planted in full sun areas. They have a garden area that is shaded by a tree, and the junipers just hate it. The mites love these weakened junipers and eat them up.
Mites are generally a fact of life, they are everywhere, but sometimes, environmental issues are the causes of infestations, and that is what you want to prevent.

__________________
Emerging from winter slumber
Bonsai trees burst buds anew
Spring is upon us!


-Paul S.

RonMartin(deceased)

Well a healthy tree will fight off insects. Or at least have a better chance of it.
But as you said mites are every where. Environmental issues are not generally the cause, just how well the tree can withstand the infestation. Most of the time the environment does favor the bug ;o(

duartix

Here is a picture of the victim. A chinese elm in the bathtub.

I've been keeping it in a partial shaded area (under a green net shadow).
It's in a 14th floor balcony, so ventilation is no problem.
It's 200m from the river, so humidity should be no problem either.

I could be overfertilizing it though.

I've been giving it showers for the last 3 days and misting all my trees at night. This particulary tree may have lost around 20% of it's leaves during the showers.

My concearn now is with the new leaves which as you can see are coming as a very light and pale green. This is not their normal colour.

I'm still keeping it in partial shade.
Show I take any more measures?

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heymikey(deceased)

hey Duartix; Your elm tree's leaves indicate some clorosis (yellowish between darker green veins). This may be due to poor soil drainage, compacted/damaged roots, or soil pH too high (alkaline) which prevents the uptake of iron. It is recommended that you keep the soil from getting too much water during your showering and only water the soil when needed. With Lisbon's high temps only in the 60's F. watering may only be needed every 2-4 days depending on soil structure, sunlight, humidity, etc. Also, I feel that elms can use much more sunlight (specially in spring) and you indicated that it gets mostly shade. Regards, heyMikey!!

Camay123

One of my books talk bout those small spider appearing when the tree is lacking light and ventillation. Maybe yuour partial shade screen is giving proper condition for the mites.

You should still mist them at night. The same boook says that the temperature change from day tro night while having the tree expose to sun, will slow down the mites develloppement.

some of the product suggest in an other book, altough it's a book made in Quebec recoomaned those product :

Safer ; Malathion ; Diazinon ; Keltane

Some of them are generic insecticide product.

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Camay123

Before using any chemical insecticide I prefer to use something ecological like an insecticide soap or a spray in a can.

__________________
Selling Bonsai tree seeds.
Flat rate shipping fee worldwide
Over 50 species in stock
Germination instructions

duartix

Thank you, everyone!

@Heymikey:
You are right! Even though I cover the soil with plastic before showering, the soil has been very wet lately. I'll move the tree to total sun exposure, at least until the Summer comes burning in...

@Camay123:
I'm following the toxicity route:
1 - Water
2 - Insecticidal Soap (perhaps with some home aditives like crushed malaguettas)
3 - Chemicals

I've been talking to a friend of mine who has been studying Landscape Architecture about IPM, because I hoped he could get me some predators, but he tells me there is little use of it here in Portugal.