Noticed these black spots on my 'Seiun kaku' about 4 days ago. We've had a very wet spring and early summer, and the media the tree is in is less than ideal. The two small branches have since been pruned out. Is there anything else I can/should do? Thanks, Kyle
It looks like a bacterial infections and bacterial leaf scorch and or root rot. The stress of having soil that is staying too moist and lacking oxygen to the roots is probably the primary cause. Remove the tree from direct sun. The roots can't take up moisture without oxygen. In their current state they can't stand up to full sun, bright shade would be ideal. You need more oxygen to the roots. Since you are still working on a better potting mix, you may need to consider some quick solutions to improve oxygen and reduce the risk of root rot. Options include: -vertical mulch to improve the soil. -make sure drainage holes are open. -consider raising the pot away from a wet surface especially if drain holes are facing the bottom that could be sealed by a wet surface. This could be done by placing the pot on 2"x2" feet or by placing them on top of a bed of pine bark nuggets to increase airflow under the pot keeping it away from stagnant water. -consider drilling additional drainage holes at the bottom on the sides of the pot wall. -consider drilling random 1/4"-1/2" holes in the plastic pot walls to improve oxygen and reduce saturation. -remove tree from pot and grow in cedar planter box in a better planting mix (mix as discussed in other thread once ingredients are sourced).
In addition to the post above, when you re-pot consider the pot width when selecting a new pot. I have found over the years a pot that is narrow and tall does not lend itself well to growing Japanese maples. Instead go with a wider pot for several reasons. A wider pot has greater surface area allowing more: -oxygen to the roots -room for surface feeder roots to grow -evaporation to prevent soil from staying too saturated reducing the risk of root rot. Other more obvious reasons are a narrow pot: -is more likely to blow over -has less area to catch rainfall and as the canopy leaves direct rain to the outer lower branch tips, the rain will drip outside of the pot perimeter missing the roots all together -soil becomes quickly compacted as roots fill the narrow area -root zone is less insulated from extreme Summer heat and Winter freeze. Japanese maples will grow in a tall narrow pot, but the tree will suffer. The tree will not grow as well and will eventually stop growing, will more likely have root related issues due to moisture imbalance and temperature damage, require re-potting more often, require more water maintenance, and may suffer damage from blowing over. Balance is always key because a pot that is very wide and too shallow can invite it's own problems.
Hi Kyle, I do think these are pseudomonas bacterial infections, in as much as anyone can tell anything from a photo. 100% agreement on pot shape with John. I experimented with this at one time. For best drainage I use SBX pots. I have had good success with immediate oxygenation using a hydrogen peroxide solution (care is needed no to make it too strong, which will kill the maple very quickly). Spraying with copper solution is effective in fighting these infections, though as John suggests the infection may be secondary: e.g. too wet roots (so lacking oxygen) may be weakening the plant, so it gets the bacterial infection that it would otherwise fight off. -E
For a quick understanding on how Pythium (root rot) occurs and how it opens the door to other soil born pathogens, check out this short and to the point video: And, this video on rhizoctonia root rot Note that the video is not specific to Japanese maples (not a major cash crop, therefore lacks funding) but all the information applies. These are great for those who grow Japanese maples by seed and want to understand why their seeds fail.
Thank you both, very much. Luckily, the pot is actually rather wide and sits on a large rock. I know for a fact the soil it is in is crappy, however. So I shall plan on vertical mulching as soon as I find the stuff. I went to a large garden center near my university this past week and was shocked to see even they didn't have pine fines or sharp silica or haydite :(. I am just going to order stuff online I believe. I will also move the pot where it doesn't receive rain to let it dry out some. Thanks, Kyle
I suspect that "Del Rio" is in a very sunny, dry state (?: sounds like a US southwest location to me, Az, Utah, South Cal, Tx, New Mexico, ... ). What do you mean by "it sits on a large rock"? A rock will gather the heat, and give it back even during the night, like the bricks of a pizzeria oven. I don't think that putting a pot on a rock in a hot place is a very good option, the plant will be overcooked very quickly. EDIT: looked up "del Rio" on wikipedia, and if it's "Del Rio, Texas", my, it's much too hot for a Japanese maple to sit on a rock... "...The climate is semiarid in moisture and subtropical in temperature." Del Rio, Texas - Wikipedia
Lol, actually I live in East Tennessee. Very near the Great Smoky Mountains. So it's warm and very humid here, not very hot, especially not dry heat. What I mean by "it sits on a rock" is that there's a large quartz rock, I assume placed for decoration by the family who lived here before me, that is about a meter wide and very flat that the pot sits on top of.
I get my haydite from: HAYDITE - DiGeronimo Aggregates LLC I get the bonsai blend for all my container grown maples and bonsai. When I first contacted them 5 years ago they offered shipping and over the phone transactions. I know that many who sell online buy from them and then bag up small quantities for a huge mark up. They are close enough to me that we pick it up. They seem to always be shipping the stuff in (I believe) 20lb bags. Unless something has recently changed, you may want to price shop them instead of buying excessively marked up small quantities online. I hope this helps.
I came across this website this morning and thought it might be worth considering as an online option for soil amendments: Browse All Aggregates If I were in your shoes I would consider their: American Bonsai Ultra Mini Mix American Bonsai Ultra Mix American Bonsai UltraAgg: Organic Pine Bark
Our pine bark comes from: Mulch Manufacturing, Inc. for Landscaping Maybe they have a retailer close to you?
This is a link to the product page of the pine fines and soil conditioner we use: Mulch Manufacturing, Inc. for Landscaping Once on the products page, along the left navigation bar, look under Pine and click on "Pine Mulch" and also "Soil Conditioner".
The 'Seiun kaku' in question is still alive and looking some better, but still not happy due to wet feet. I now have the ingredients to make a good media. Should I wait for the tree to go dormant before I repot? Or would doing it now be better since it would have time to grow some more roots before it gets cold?
You know, you could have simply knocked off the pot some time ago to dry out the root ball? Nevertheless, repotting now is a better idea than waiting until after leaf fall for the reason you stated. 'Repotting' can mean lots of things. If you are going to bare root it (wash and comb away all that 'crappy' soil), it will need to be kept in heavy shade and maybe even in a humidity tent for about 2 weeks. If you are going to leave it mostly intact, just loosening the roots on the surfaces before sitting it in a larger pot; that can be done anytime without a worry. Care afterward will be somewhere in between depending on the degree to which you disturb the total rootage (fine root damage, in other words) between those two extremes.
