This is a time of year when our trees are almost dormant. The more or less constant high heat has caused the process of photosynthesis to slow down. There is an optimal growing temperature for all trees, and each is a little bit different. Pines, Junipers, Cypress and other conifers should be showing a lot of brown/yellow needles or scale growth due to the fact that they are putting a lot of their energy into forming new buds. As the new growth is formed the older growth must be abandoned because it is simply not as efficient as the new growth. Remove the brown needles with your hands or tweezers and your bon- sai will look a lot nicer.
For our deciduous trees the leaves are beginning to tire. They have been working hard since March/April to produce more tree and the molecules that conduct photosynthesis are starting to wear down. During this time it is possible to repot maples, elms, oaks, beech, crab apple, wisteria, and many other deciduous bonsai. As long as the roots are not treated too harshly the trees will still have time to make leaves before the weather gets too dark and cold for them to produce the proteins, carbohydrates and sugars the tree needs to grow. If repotting is needed remove all the leaves and go ahead. In October/November the leaves will begin to change color with most of them falling by December here at the nursery.
The last three weeks of June and the first week of July have been perfect examples of “Global Wierding”. Everything I thought I knew about the weather, and I learned a lot being out in the woods for twenty years and growing bonsai for many more, is all for naught. One day it is 105 with a nighttime low of 92 and the next day (I mean the very next day) it is 80 with a nighttime low of 60. These wild swings of temperature do bad things to our trees. Most frequently with deciduous material the leaf margin will turn brown or yellow, or the leaves will be deformed, or the tree may simply drop all its leaves. If your trees are in the sun a lot of this damage will occur because the pot gets very hot.
For Junipers and Pines it is different. They like the heat and sun but they often suffer when temperatures fluctuate over about 25 degrees from one day to the next. With conifers and junipers damage takes much longer to be manifest. It can often take a couple of months for your pine tree’s needles to turn yellow after it has been burned.
Remember all of our new roots and tender young shoots are growing right next to the inside wall of the pot. If it is a ceramic container the temperatures where the roots are trying to grow can get over 140 degrees. Guess what happens… the roots in that zone die. The tips of your pine needles will start to turn brown and the needles will die back down from the tip. Junipers will start to drop weak limbs. All the foliage will turn yellow or brown and the branch will die.
This is becoming more of a problem in the last 10-15 years than it ever was before. During my visits to Asia, I find that bonsai nursery persons over there are having to be more careful with their trees. Wrapping the pots with burlap, swamp cooler pads, or wet rags will really help. If possible move the trees into full shade or a space with morning sun only. Don’t be afraid to water two or three times a day. If your bonsai are in good soil there will not be a problem. You can spray the leaves with Cloud Cover or Anti Stress 2000. Both of these are a harmless latex coating that will reduce water loss through evapo-transpiration.
If your tree looks ugly and it is good and strong, move it into a shady spot and cut off all the leaves. It will revive in about a months and look good. If it is weak move it into the coolest spot you can find and let it rest. As the leaves die, you should be able to see tiny little buds emerging right at the base of each leaf. On pine there should be new buds right below where the old needles are dying. For Junipers look into the base of the dying branch or on a strong branch nearby and you should see new lime colored growth.
Remember, Mother Nature does not even know we’re here and she can be a wild and crazy girl.
Things have been very busy here at Lotus Bonsai. We took a group of 12 persons to the Eastern Sierra’s east of Bishop and then up to Mammoth Mountain. This trip was at the same time as our last club meeting. We are also working on places to go for Sierra Junipers and will keep you posted on our progress. Going to the high desert and great mountains of the west is always very cool.
In addition Greg, Paul Holtzen and I are the main persons running the 2012 GSBF annual convention in Sacramento at the Double Tree Hotel, October 25-28. Hope a bunch of our club members can attend to join in the festivities, check out the exhibits and look over the Vendors area for the best prices.
Here at Lotus we grow a lot of different Japanese Maples and this time of year they are usually turning gold, orange, red, and pink. This year the leaves are turning brown and falling off the trees. I think it must be the great fluctuations in temperature we had back in February, March, and April. My diary shows that we had temperature differences of up to 40 degrees over 4 days. From hot to cold then back to hot again. No won- der our trees are confused. A couple of exceptions to the leaf deal are the Amur Maples and Sweet Gums which are putting on a pretty good show.
You can use Liquinox 0-10-10 on you trees now to get the roots prepped for winter. Usually 2 tablespoons in a gallon of water applied every 2 weeks until the end of November. Lots of Yellow Jackets this year but not many other bugs. The aphids showed up in mid June but never really got a foothold. There was also quite a bit of powdery mildew this year. You can control powdery mildew by spraying your trees 3x with a dormant oil this winter when they are asleep.
As most of you have discovered this is the time of year we begin finding Aphids on our deciduous trees. There is also the appearance of scale insects. It is my experience that where those two critters show up ants, powdery mildew and sooty mold cannot be far behind.
Here are some suggestions:
1). Aphids are small sap suckers that come in about a dozen different varieties. They are here now because there are a lot of young tender, juicy shoots for them to suck on. As they suck out the sap from our trees they poop a clear sticky fluid called “Honeydew” of all things. Ants love this poo and consume large quanti- ties of it. Ants carry the fungus base for sooty mold on their little shoes. So lots of ants are a problem for us. Also ants will set up shop keeping and homestead your pots which is a big problem. Solution: Watch closely as these little guy’s can take over a tree before you even know about it. They are not easy to see on a casual inspection. They are routinely under the leaves and at the very tip end of the new shoots. Lady bugs and Praying Mantids will consume millions of these little aphids every day. The only problem is that the Lady bugs don’t start moving around until it warms up and it is still too cool for the Praying Mantid egg cases to hatch out. Use Insecticidal Soap or agricultural oil (Neem, Volk, or Stylet oil) for control. Try to spray sparingly be- cause these products will also take out our beneficial buddies. You will need to treat the trees at least 3-5 times to eliminate the bugs. Spray early in the morning or late in the afternoon early evening. Do not ap- ply anything to your trees during the heat of the day. You can also defoliate and then spray the tree with a strong stream of water washing all the aphids off.
2). Scale insects are quite a story. I will not bore you with all the details (go to Google and you will see what I mean), suffice it to say that they are really tough customers. They are like the Mike Tyson of bugs. There are 5 types that show up here every year. They love our fruit trees, Apple, Pear, Cherry, etc. are all like candy to them. They will appear as shiny, hard little bumps on the branches, they usually do not get on the leaf. When you smash them sticky juice comes out, that is your tree they are eating inside that little fort they have constructed. They don’t move once they have set up shop. You need to use oil on them at least 5-7 times. Spray every three days for 2 or 3 weeks. Mashing them works good and is very satisfying. Both of these insects will not usually kill your tree but they make everything a big mess, bring a lot of other problems with them and will weaken the tree. If you see Lady bugs or Praying Mantids do not spray; these guy’s are really efficient Aphid predators. For the scale you will need to spray and smash.
3). Powdery Mildew and Sooty Mold should be treated with any of a dozen fungicides. Oil also can help out quit a bit. Pulling off the leaves works good for powdery mildew. Sooty mold (the bark and branches of your tree will appear to be getting dark grey to black in color) is a tough thing to eradicate once it is on your tree. Fungicide will work but it takes many applications over 2 growing season. I have had some success power washing the trees when they are dormant, be careful not to scrub the bark off. Sooty mold appears on our Elms, Oaks, Zelkova’s, and fruit trees mostly, although it is occasionally found on some others.