HPBudlong wrote:

I had a beautiful orange tree anout 15 feet tall with incredible oranges -
Valencia - This year it gradually started dying and none of the tree people I
got in could figure out why. Any suggestions? It was watered, did not appear
to have any insect problems, although some of the leaves were a bit crinkly.
Southern Calif, Zone 9.

My dwarf 'Robertson' navel orange seemed to decline, starting in
the summer of 2003 and continuing well into this past summer.
Seemingly healthy leaves would suddenly fall as soon a new growth
started. Branches were dying back. It failed to set any fruit.

I sprayed it with Malathion to combat spider mites (mixing some
liquid soap with the spray as a wetting agent). I fed it
frequently but lightly, using commercial citrus food plus zinc
sulfate (which I no longer see in the nurseries); I also gave it
occasional small amounts of ammonium sulfate. I pruned the longer
branches to ensure the top growth did not exceed the ability of
constrained roots to supply nutrients and water. And I made sure
the soil was constantly moist without ever allowing it to get
soggy.

It is now recovering. I don't know which of my actions is making
it recover. However, it stopped dropping leaves; and I no longer
see die-back. With winter near, I've stopped feeding because I
don't want tender new growth when we get frost. But I'm still
watering frequently.

If the weather is okay this weekend, I plant to move the orange
into a new terracotta pot. Its redwood tub is rotting away. The
tub is cylendrical, with inside diameter and depth both 18 inches.
The pot is 17 inches deep inside and slightly tapered, with the
bottom inside diameter 16 inches and the top 20 inches; that's 5%
less volume than the tub. Yes, I will have to cut away part of the
rootball.

--
David E. Ross
Climate: California Mediterranean
Sunset Zone: 21 -- interior Santa Monica Mountains with some ocean
influence (USDA 10a, very close to Sunset Zone 19)
Gardening pages at http://www.rossde.com/garden/