On 4/17/2009 11:44 PM, Ablang wrote:
I was at the nursery and I noticed, especially for the fruit trees,
that they had white paper sleeves around the trunks of the trees...

Does anyone know why they do that, and will that benefit other trees
as well?

Even mature citrus trees can suffer sunburn on their trunks. Sunset says:
"Citrus bank sunburns in hot-sun areas. Thunks should be wrapped (paper
trunk bands are available commercially). When heavy pruning exposes
trunks or limbs, protect bark with whitewash or latex paint diluted by
half with water."

Citrus does not require pruning to produce fruit. Pruning is required
only to remove dead or crossing branches. Thus, a good canopy of
foliage eliminates the need to protect the bark.

My citrus are actually semi-dwarf and not true dwarf. Even semi-dwarf
citrus will not develop the extensive canopy of foliage to protect the
bark. I solved this problem by growing my dwarf citrus in partial shade.
Citrus requires summer heat, which mine get, but not necessarily full
sun. I've heard that citrus is grown commercially in low desert areas
of California in the total shade from date palms (two crops from one
orchard).

--
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 diary at http://www.rossde.com/garden/diary