I have a problem y almost all my Bonsais, black tips on the leaves, new leaves and already grown ones.
All of them are in volcanic soil (the only inorganic soil available in Chile). I think it could be a problem related to toom much watering, here is later winter and became warmer. I was watering twice a day, as soon as the first soil layer is dry, but two inch below was still wet. Therefore, I guess I was watering wrong for almost 3 weeks.
I am using the following systemic fungicide. I appreciate any advice about that.
The problem is over watering. I would water about every 3 or 4 days in early spring. Later in spring you can see that the bottom soil will dry out faster…then you can water every 2 days or less. In summer is the best time to water everyday and it pretty safe to do so as everything is so dry and hot.
I agree that it is probably too much water. Top dressing helps keep the moisture in the soil column more uniform and promotes root growth near the soil surface. Shredded sphagnum moss + local green moss is traditional. However, I imagine that a variety of organic materials like that could work.
@wilson_chiesa why do you think you need a fungicide? I would skip it and see if the leaves come out without the black tips once you reduce the watering. I tend to use a minimal amount of insecticide and fungicide and only when I identify an actual problem.
I always feel that the less fungicides in the environment, the better. If they are really necessary, fine, but usually the problem lies in the cultivation - too much/not enough water, sun, humidity, etc. I had quite a problem with my JBPs getting white fluffy stuff on the needles, but then moved them to a more arid part of the yard, away from other shrubs and they are much better. (Sorry, a bit OT there).
+1 to topdressing! Add some shredded sphagnum moss (or the local equivalent), and water only when that layer is fully dry (but peek under to make sure the soil is dry under the moss, too).
