A few of my rhododendrons' leaves are showing a loss of color this winter.
They look almost white with green speckling. Anyone know what this is and
what I can do for it?

Thanks.

Karen
portland, or

Sounds as if they would benefit from a height nitrogen feed

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

Does this mean applying a nitrogen solution to the leaves?

karen

"David Hill" wrote in message
...
Sounds as if they would benefit from a height nitrogen feed

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

In article , "Anonny Moose"
wrote:

A few of my rhododendrons' leaves are showing a loss of color this winter.
They look almost white with green speckling. Anyone know what this is and
what I can do for it?

Thanks.

Karen
portland, or

When SPOTS appear on leaves in winter, it can be any number of problems
causing ill health to the root system -- such as borers or fungus -- &
winter spottiness is just the first sign of worse to come. But if the
whole leaf is just fading to yellow between the leaf-veins, the shrub is
chlorotic, which is repairable. This happens to all plants that prefer
acidic soil that end up in poor or alkaline soil. Some people induce the
problem if they add fireplace ashes to gardens, believing this is
beneficial when it can be very harmful to rhodies, roses, blueberries,
apple & cherry trees, by alkalinizing soil. If you've gone the "ashes are
good" route then you've injured the soil for rhodies. If that is the
case, rain & waterings will eventually wash out the alkalinity, unless
your local soils are naturally alkaline, then it's going to be a recurring
harrassment to ammend soils to acidic conditions unnatural for your area.

Over fertilizing or the wrong fertilizer can also cause chlorotic
conditions by interferring with rhodies' capacity to take in iron. Heavy
feeding of phosphorus intefers with iron uptake even if the iron quantity
in the soil is sufficient. Run-off from newly laid concrete or cement, OR
unstable deteriorating old cement, can alkalinize the immediate area
(stable well-cured cement is NOT a problem though). If you lime a nearby
lawn, this can leech into areas of woody shrubs, damaging the soil for
many perennials & shrubs & fruit trees -- what's good for lawns is not
always good for much else, so take care not to lime lawns too near
gardened areas.

The usual "fix" is sulfer or iron sulfate. This assumes the soil does have
iron in it but that alkalinity or other factor hinders uptake of iron. A
mere tablespoon of sulfer in the soil around the base of each shrub will
help it take in the iron it needs. If there's something continuously
keeping the area to the alkaline side of the pH scale, it will need a tiny
bit of sulfer EVERY spring. But this is a compensating method, not a real
restoration if the soil has been alkalinized. A great amount of peat
worked into the soil & heavy topcoatings of leafmold & composted manure
will help acidify the soil itself & increase plant health. Be VERY careful
with fertilizers that shoudl be low in nitrogen & low in phosphorus; until
alkalinity can be reduced, no amount of even a properly balanced
rhody/azalea fertilizer will help, because the problem is that the shrub
cannot take in iron when soil is limey.

Very rarely excessively acidic soil is the culprit, as even acid-loving
plants such as rhodies want only moderate acidity. In such a case a little
lime actually helps rather than increases the problem. So you need to know
your specific pH conditions before knowing which action to take, as lime
will increase the problem if the soil is alkaline, & help the problem if
the soil is super-acidic.

Though naturally alkaline soil or soil damaged by excesses of phosphorus
or lime or ashes are commonest culptrits, sometimes the soil is fine &
some other thing causes chlorosis, but the other causes would usually mean
the shrub did not do well for a few years before began to show stress, but
always struggled in the given location. Compacted, poorly draining,
clayey, over wet soil destroys a rhody's capacity to take in iron, as does
being planted too deep (their roots must remain "in the shallow." These
conditions usually cause root stress & disease or attract insect damage
the first sign of which will be either winter spottiness OR chlorosis. A
greater amount of peat or other organic material in the ENTIRE garden,
well-loosened for better aeration.

If soil is literally iron deficient or magnesium depleted, this can be
narrowly resotred. A feeding of liquid chelated iron according to product
directions will be the proper fix or iron deficiency. For magnesium
depletion, a high-magnesium low-nitrogen evergreen fertilizer, or just
epsom salts (magnesium sulfate) will fix that. Some recommend a
combination chelated iron with magnesium sulfate together as kind of
broad-spectrum approach. But tinkering with soil chemistry repeatedly will
in the long run do more harm than good & the original cause of the problem
should not be permitted to continue, so that organically rich slightly
acidic soils remain in prime condition by means of healthful annual
topcoatings of leafmold or manure compost. Without knowing the soil
conditions beforehand, & without knowing why the soil went wonky if it was
previously just fine, any action you take could turn out to be wrong.
You'll know fast if the action you take was helpful, as it takes only
about two weeks to begin turning back to green.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/

In article , "Anonny Moose"
wrote:

Does this mean applying a nitrogen solution to the leaves?

karen

Nitrogen is not likely to help since rhodies are low-nitrogen users to
begin with. Spottiness (in winter) is evidence of root stress or illness;
paleness of leaves between veins (at any time of year) is evidence of the
plant's inability to take in iron.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/

Does this mean applying a nitrogen solution to the leaves?

karen

"David Hill" wrote in message
...
Sounds as if they would benefit from a height nitrogen feed

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

In article , "Anonny Moose"
wrote:

A few of my rhododendrons' leaves are showing a loss of color this winter.
They look almost white with green speckling. Anyone know what this is and
what I can do for it?

Thanks.

Karen
portland, or

When SPOTS appear on leaves in winter, it can be any number of problems
causing ill health to the root system -- such as borers or fungus -- &
winter spottiness is just the first sign of worse to come. But if the
whole leaf is just fading to yellow between the leaf-veins, the shrub is
chlorotic, which is repairable. This happens to all plants that prefer
acidic soil that end up in poor or alkaline soil. Some people induce the
problem if they add fireplace ashes to gardens, believing this is
beneficial when it can be very harmful to rhodies, roses, blueberries,
apple & cherry trees, by alkalinizing soil. If you've gone the "ashes are
good" route then you've injured the soil for rhodies. If that is the
case, rain & waterings will eventually wash out the alkalinity, unless
your local soils are naturally alkaline, then it's going to be a recurring
harrassment to ammend soils to acidic conditions unnatural for your area.

Over fertilizing or the wrong fertilizer can also cause chlorotic
conditions by interferring with rhodies' capacity to take in iron. Heavy
feeding of phosphorus intefers with iron uptake even if the iron quantity
in the soil is sufficient. Run-off from newly laid concrete or cement, OR
unstable deteriorating old cement, can alkalinize the immediate area
(stable well-cured cement is NOT a problem though). If you lime a nearby
lawn, this can leech into areas of woody shrubs, damaging the soil for
many perennials & shrubs & fruit trees -- what's good for lawns is not
always good for much else, so take care not to lime lawns too near
gardened areas.

The usual "fix" is sulfer or iron sulfate. This assumes the soil does have
iron in it but that alkalinity or other factor hinders uptake of iron. A
mere tablespoon of sulfer in the soil around the base of each shrub will
help it take in the iron it needs. If there's something continuously
keeping the area to the alkaline side of the pH scale, it will need a tiny
bit of sulfer EVERY spring. But this is a compensating method, not a real
restoration if the soil has been alkalinized. A great amount of peat
worked into the soil & heavy topcoatings of leafmold & composted manure
will help acidify the soil itself & increase plant health. Be VERY careful
with fertilizers that shoudl be low in nitrogen & low in phosphorus; until
alkalinity can be reduced, no amount of even a properly balanced
rhody/azalea fertilizer will help, because the problem is that the shrub
cannot take in iron when soil is limey.

Very rarely excessively acidic soil is the culprit, as even acid-loving
plants such as rhodies want only moderate acidity. In such a case a little
lime actually helps rather than increases the problem. So you need to know
your specific pH conditions before knowing which action to take, as lime
will increase the problem if the soil is alkaline, & help the problem if
the soil is super-acidic.

Though naturally alkaline soil or soil damaged by excesses of phosphorus
or lime or ashes are commonest culptrits, sometimes the soil is fine &
some other thing causes chlorosis, but the other causes would usually mean
the shrub did not do well for a few years before began to show stress, but
always struggled in the given location. Compacted, poorly draining,
clayey, over wet soil destroys a rhody's capacity to take in iron, as does
being planted too deep (their roots must remain "in the shallow." These
conditions usually cause root stress & disease or attract insect damage
the first sign of which will be either winter spottiness OR chlorosis. A
greater amount of peat or other organic material in the ENTIRE garden,
well-loosened for better aeration.

If soil is literally iron deficient or magnesium depleted, this can be
narrowly resotred. A feeding of liquid chelated iron according to product
directions will be the proper fix or iron deficiency. For magnesium
depletion, a high-magnesium low-nitrogen evergreen fertilizer, or just
epsom salts (magnesium sulfate) will fix that. Some recommend a
combination chelated iron with magnesium sulfate together as kind of
broad-spectrum approach. But tinkering with soil chemistry repeatedly will
in the long run do more harm than good & the original cause of the problem
should not be permitted to continue, so that organically rich slightly
acidic soils remain in prime condition by means of healthful annual
topcoatings of leafmold or manure compost. Without knowing the soil
conditions beforehand, & without knowing why the soil went wonky if it was
previously just fine, any action you take could turn out to be wrong.
You'll know fast if the action you take was helpful, as it takes only
about two weeks to begin turning back to green.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/

In article , "Anonny Moose"
wrote:

Does this mean applying a nitrogen solution to the leaves?

karen

Nitrogen is not likely to help since rhodies are low-nitrogen users to
begin with. Spottiness (in winter) is evidence of root stress or illness;
paleness of leaves between veins (at any time of year) is evidence of the
plant's inability to take in iron.

-paghat the ratgirl

--
"Of what are you afraid, my child?" inquired the kindly teacher.
"Oh, sir! The flowers, they are wild," replied the timid creature.
-from Peter Newell's "Wild Flowers"
See the Garden of Paghat the Ratgirl: http://www.paghat.com/

Whilst I cant fault phagat's instruction for Rhodo growing.....I find that
some of mine show yellowing of the leaves every couple of years and I am on
a soil with a ph of around 5.
I use a handful or two (Depending on the size if the bush) of Nitro
chalk...which is a very high nitrogen fertilizer.........
If you do try this route then on no account let it get onto the leaves, it
will burn them fast.
Apply to the ground around the bush. You could water it on to the soil. but
I would do nothing now till the spring.
I find I have to do the same with my camellias and Azaleas....

If you can test the soil to find out the ph it will help decide on how to
treat them.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

Whilst I cant fault phagat's instruction for Rhodo growing.....I find that
some of mine show yellowing of the leaves every couple of years and I am on
a soil with a ph of around 5.
I use a handful or two (Depending on the size if the bush) of Nitro
chalk...which is a very high nitrogen fertilizer.........
If you do try this route then on no account let it get onto the leaves, it
will burn them fast.
Apply to the ground around the bush. You could water it on to the soil. but
I would do nothing now till the spring.
I find I have to do the same with my camellias and Azaleas....

If you can test the soil to find out the ph it will help decide on how to
treat them.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk

Check the undersides of the leaves for evidence of Lacebug poop... will look
like black pepper.

Dave

"Anonny Moose" wrote in message
...
A few of my rhododendrons' leaves are showing a loss of color this winter.
They look almost white with green speckling. Anyone know what this is and
what I can do for it?

Thanks.

Karen
portland, or

"David J Bockman" wrote in message
...
Check the undersides of the leaves for evidence of Lacebug poop... will
look
like black pepper.

I agree with David that what you describe sounds like the results of a
lacebug infestation, but winter is an unusual time of year for this to show
itself. Lacebugs are typically present during the growing season, but winter
stress from excessive cold (like you experienced several weeks ago) may have
amplified what was overlooked earlier in the season. Eggs overwinter on the
underside of the leaf close to the midribs. Hosing off or applying an
insectidicidal soap is your best control method. Will need to repply when
they hatch in May and again in late June or early July. Rhododendrons grown
in much sun seem to be more prone to damage from lacebugs than those grown
in a cooler, shadier position.

pam - gardengal



"Anonny Moose" wrote in message
...
A few of my rhododendrons' leaves are showing a loss of color this
winter.
They look almost white with green speckling. Anyone know what this is
and
what I can do for it?

Thanks.

Karen
portland, or

Kind gardeners,

I just pulled a couple of leaves for a better look and have to admit my
initial description was a bit off. The topside of the leaves has
yellow-white very fine speckling or mottling, and there is also dark
mottling on top and bottom that looks like physiological leaf spot. There is
no notching (root weevil) but close inspection reveals a couple of tiny
light-colored insects on the underside (maybe one or two on each leaf), too
small to make out details using a 10X loupe. The pictures of rhodie lace bug
damage look quite a bit like what I'm trying to describe, along with the
physiological leaf spot. It doesn't look to me like powdery mildew or gray
blight, whitefly, rust or virus; definitely not chlorosis.

There has been no lime or wood ash added to the soil. I mulch with leaves
and compost and added one or two applications of a rhodie food over the
season. A soil test taken early last year returned a pH of 6.2. The sample
was very low in sulfur, very high in iron and phosphorus, high in organic
matter, potassium and zinc. The Comments mention low levels of sulfur may
cause yellowing and lack of vigor but that sulfates may have leached below
the sampling depth. Boron level was 0.4 and Comments suggest aiming for
levels above 0.5 ppm to avoid deficiency.

What would be the best way to add sulfur and boron? One of the posts
suggested treatment for lace bug, so I'll copy that and give it a try. Hope
I haven't lost them yet! Any other thoughts would be appreciated.

Thanks all.

Karen
Portland, OR

Kind gardeners,

I just pulled a couple of leaves for a better look and have to admit my
initial description was a bit off. The topside of the leaves has
yellow-white very fine speckling or mottling, and there is also dark
mottling on top and bottom that looks like physiological leaf spot. There is
no notching (root weevil) but close inspection reveals a couple of tiny
light-colored insects on the underside (maybe one or two on each leaf), too
small to make out details using a 10X loupe. The pictures of rhodie lace bug
damage look quite a bit like what I'm trying to describe, along with the
physiological leaf spot. It doesn't look to me like powdery mildew or gray
blight, whitefly, rust or virus; definitely not chlorosis.

There has been no lime or wood ash added to the soil. I mulch with leaves
and compost and added one or two applications of a rhodie food over the
season. A soil test taken early last year returned a pH of 6.2. The sample
was very low in sulfur, very high in iron and phosphorus, high in organic
matter, potassium and zinc. The Comments mention low levels of sulfur may
cause yellowing and lack of vigor but that sulfates may have leached below
the sampling depth. Boron level was 0.4 and Comments suggest aiming for
levels above 0.5 ppm to avoid deficiency.

What would be the best way to add sulfur and boron? One of the posts
suggested treatment for lace bug, so I'll copy that and give it a try. Hope
I haven't lost them yet! Any other thoughts would be appreciated.

Thanks all.

Karen
Portland, OR

Kind gardeners,

I just pulled a couple of leaves for a better look and have to admit my
initial description was a bit off. The topside of the leaves has
yellow-white very fine speckling or mottling, and there is also dark
mottling on top and bottom that looks like physiological leaf spot. There is
no notching (root weevil) but close inspection reveals a couple of tiny
light-colored insects on the underside (maybe one or two on each leaf), too
small to make out details using a 10X loupe. The pictures of rhodie lace bug
damage look quite a bit like what I'm trying to describe, along with the
physiological leaf spot. It doesn't look to me like powdery mildew or gray
blight, whitefly, rust or virus; definitely not chlorosis.

There has been no lime or wood ash added to the soil. I mulch with leaves
and compost and added one or two applications of a rhodie food over the
season. A soil test taken early last year returned a pH of 6.2. The sample
was very low in sulfur, very high in iron and phosphorus, high in organic
matter, potassium and zinc. The Comments mention low levels of sulfur may
cause yellowing and lack of vigor but that sulfates may have leached below
the sampling depth. Boron level was 0.4 and Comments suggest aiming for
levels above 0.5 ppm to avoid deficiency.

What would be the best way to add sulfur and boron? One of the posts
suggested treatment for lace bug, so I'll copy that and give it a try. Hope
I haven't lost them yet! Any other thoughts would be appreciated.

Thanks all.

Karen
Portland, OR