The other possibility might be a virus. Roses can get a mosaic virus that
causes the leaves to change color. Often it doesn't kill the plant, but will
weaken it over time.

"Leaf Symptoms

Leaf symptoms of RM are highly variable, often making diagnosis difficult.
Some rose cultivars show strong symptoms, while others may be nearly
symptomless. Most cultivars will be symptomless for at least part of the
year. The most severe symptoms usually are seen during cool weather, in the
spring, and are much less severe during the summer months. Some leaves may
show "vein-banding", in which the veins are bright orange or yellow, on a
green background. Other leaves may show a bright yellow or white "oak leaf"
or "mosaic" pattern . A very faint "watermark" chlorosis is common on the
leaves of some cultivars . These symptoms often fade as the leaf ages and
may disappear completely. The chlorotic patterns associated with RM usually
do not closely resemble any mineral nutrient deficiency or herbicide
toxicity pattern and are reasonably reliable for diagnosing RM. The absence
of any obvious symptoms is normal, and is no guarantee of freedom from RM;
some infected cultivars seldom show symptoms, but their performance may be
impaired."
http://members.aol.com/mmmavocad3/Mosaic.html


"Sed5555" wrote in message
...
We've 10 different types of roses in out backyard...one of them has many
of
its leaves turning yelloe to white.

It could be iron chlorosis, which is common in roses. It results from the
plant's inability to absorb iron (more prevelant in alkaline soil). This
particular rose may be more susceptible than your other roses. Chelated
iron
can be applied as a foliar spray for quick results or added to the soil
for a
longer lasting effective.
sed5555