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David E. Ross · 02-05-2007, 10:38 PM posted to rec.gardens

wrote:
Hello everyone,

I have an old orange tree in northern Florida, about 20 year old I
guess, that has been doing badly since last summer. The problem is
that the tree is experiencing lots of leaf drop. The leaves become
yellow before they drop. I see no obvious signs of pests, such as
discoloration. The tree is trying to put out new shoots, but those
leaves yellow and fall before too long. The extremities of many of
the longer branches are now dead, and I fear that the whole tree is
dying.

The tree is mulched with pine needles, as it has been for years. A
few years ago, the tree was very robust, with lots of growth and a
bumper crop of fruit. I believe a former neighbor applied
fertilizer. The tree still has some fruit, but no blooms this spring.

It has been dry this spring, and I have been watering about 1 - 2
times per week. The tree handled dry spells before without any
problems.

Does anyone have any ideas? I would hate to lose this tree.

Thanks,

It might be a lack of nutrients. Citrus trees are heavy feeders. They
need an acidic mix of nitrogen, iron, and zinc. Use a commercial citrus
food; Bandini has it in sacks as small as 5 lbb. However, most citrus
food does not contain zinc; you might have to special-order a small sack
of zinc sulfate.

Mix about 2 cups of citrus food with 1/4 cup zinc sulfate. (Or mix
about 1-1/2 cup ammonium sulfate, 1/2 cup iron sulfate, and 1/4 cup zinc
sulfate.) With the soil already moist (never feed when the soil is
dry), broadcast this in the root zone, leaving an area 2 ft in radius
from the trunk unfed. Sprinkle to start disolving the fertilizer.

If the tree perks up, repeat this feeding monthly during the growing
season. If frost is ever a risk in your area, stop feeding about one
month before the expected first date of frost; resume feeding in the
spring as soon as new growth starts.

--
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/