As I mentioned on the
homepage, Madrid's climate is very extreme, low temperatures in winter
and very high and dry temperatures during summer. Summer is a very dangerous
season for my trees as the hot sun and the dry air form in fact the perfect
habitat for parasites, specially for aphids. But with the right methods
of defense it is possible to preserve the trees against these plagues.
Bonsais are very sensible plants, you should always try to use gentle remedies to not harm the tree more than necessary (instead of removing the disease). It is very important to use much smaller doses as indicated on the fabricants packages, as these are meant for normal sized plants. Some of the chemical remedies are very effective against specific assailants, but are also very aggresive for the plant, particularly the foliage can be affected if the concentration is too high, causing brown stains or even total dryout.
Avoiding chemical products, these should be always the first remedies to use:
Remove attackers with your fingers: Whenever
possible, use your fingers to remove aphids and other parasites from the
tree. This method is obviously the best to not damage the plant. But not
all plagues are caused by insects (you also have fungus, root poorness aso.), nor all the insects are big enough to be removed physically, so other treatments have to be used.
Water: Get a big
enough container to submerge the whole tree under water. Protect the soil
with a plastic cover or submerge it very carefully to keep the soil in place, keeping it from floating up to the water surface. The tree should remain submerged at
least one day. You can add a drop of soap (any liquid soap ie. to wash dish
will do) to reduce the density of the water surface. This way the aphids
will not float above the water surface, but drown.
You can also use water
as a remedy applying showers to the tree, regulating the water flow depending
on the kind of plague you are trying to temove in order to wash the parasites
off the tree. This is particularly effective in the case of "big"
parasites as there are ie. louses or aphids. Water showers are always
a very good preventive measure against all kind of diseases and parasites,
specially those which prefer hot weather and dry conditions as ie. red spider mite.
If the previous methods did not help, your tree might need a chemical treatment:
is, for me, one of the most effective remedies against all kind of aphids
and other insects or parasites of this kind. Always use in very small
doses, that is two or three drops of the product in one liter of water.
Vaporize all affected parts of the plant, specially the backside of the
leaves. Normally it is not necessary to apply the product repeatedly, if
so, let pass by at least two weeks between applications.
Anti-spider from Compo:
Great product which should be applied with the following proportion: On
1 liter of water just add the eighth part of one of the doses. Be sure
to vaporize in the shadow and to moisten every leaf individually (again, specially
the backside, that's where the spiders concentrate on).