Despite my best
efforts they died a prolonged death with the lower branches dieing off and
the die off moving up to the top.
I could never figure out why, but my best guess is an internal fungal
disease. If you get no better suggestions, use a systemic fungicide on the
tree and repeat it at suggested intervals.
OK, see, that's not how *I* make decisions on when to use a systemic fungicide. First I consult "Fungi on plants and plant products in the United States" by Farr, Bills, Chamuris and Rossman, one of the most useful books ever published (if you're a plant
pathologist). Under Sageretia, only 3 fungi are listed, none of them pathogens. This isn't surprising, since Sageretia is such an uncommon plant of little economic importance: not many people would be *looking* for diseases. So I did a Google search, an
d found an APHIS document on the risks involved in importing Sagaretia from China: "Importation of Chinese Penjing into the United States With Particular Reference to Sageretia thea, 2003."
Look how this document describes bonsai:
"The art of artificially dwarfing plants is a time-consuming and highly labor-intensive activity. The resulting plants range from approximately four inches to 60 inches in height, and the value may range from $10 to $10,000 per plant. The median price of a
n artificially dwarfed plant is close to $100 and varies with the age of the plant regardless of size. Plants imported from Asia (Japan, the People’s Republic of China and the Republic of Korea) represent approximately 80 percent of the value of the enti
re artificially dwarfed plant market in the United States ...The volume of artificially dwarfed and other dwarf plants imported into the United States increased in recent years from fewer than 600 plants in 1993 to over 54,000 plants in 1998."
The document then goes on to list all the fungi ever recorded on Sagaretia world-wide. Of these, most are foliar pathogens. A few are listed as occurring on stems: Ascochyta, Diatrypella, Phoma, Phomopsis, Leptosphaeria. Of these, it isn't clear which, i
f any, are already present in the US. The only one that would alarm me if I isolated it would be the Ascochyta; the others are probably stress-pathogens that wouldn't attack a healthy tree (although without specific epithets one can't be sure). None of th
ese pathogens attack "wood", so symptoms would be readily visible on dead twigs and identification could be easily done by Cooperative Extension. And what would they recommend? They would recommend cutting off the dead areas.
So I would not spray the plant with a systemic fungicide.
Nina, taking 20 minutes to state the obvious, but now knowing a lot more about the pests of Sageretia.
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