As I said Mike, in the other post, the orange branch of my combination tree is dying back on the main branches. Awful! My trees never had die back like this before. All the other trees and plants are doing great except this one. I don't have supplemental light on them and the sunroom is on the southwest corner, glass on three sides. They get only the light coming from the outside, on sunny days it gets toasty and nice there. All the containers are elevated on benches to the level of the windowsill. The only thing was different with this one, is that the tree was stressed by the wind, toppled over couple of times in the summer. I don't know if that played any role in the decline of the tree, but I am still hopefull.

Merry Christmas Mike and other citrus forum friends!!!

My seed grown Meiwa and Fukushu kumquats seem to be immune to WLD. It may be that the roots will provide enough water for the leaves at lower than 55F that the other citrus roots don,t. all my other trees suffer from WLD. I was unable to find any research on cold weather citrus roots abiotics anywhere

Steve

Mike, I suspect you will not find the answer you are looking for because you need to know the ambient temperature, root temperature, amount of light and the duration of each of these parameters.

Leaf drop may also be due to improper watering, so if someone says they have the proper "ratio" of light/temperature but still got leaf drop, it could be due to things like improper watering.

Vladimir, I am not looking for any answer since I already have mine. I think it's a great idea to make people aware of 'WLD', winter leaf drop, and how they cope, what they do to prevent this issue and if what they are doing is working for them. This issue can literally kill a tree or many of these fine folks in love with their inside grown trees. Something has to be done to help these folks out and not talking about it helps no one. I think it is something one can take control over putting the ideas of others to work for their own benefit, don't you agree?

'WLD' is caused my many different variables, but a good foundation in the experiences of others and their set ups, and what they do is a good start. It does happen in the darkest days of winter when our trees are at their lowest light levels, which leads me to suspect light first then temps play a crucial role and makes them very vulnerable.

Steve, good points you brought up.

Heath, I see you have yours right up against the window. Do you mind if I ask how often you water and what mix you use? Thanks for the pics!

Sunshine, that is a head scratcher! weird. What temps are you keeping your trees at? It seems that even though they may be kept on the warmer side of things, they do get plenty of sunlight? How many hors of sunlight do they get?

There are some apps available for iPhone and Android that will use the camera on your smartphone as a light-meter of sorts. I think it would be really interesting and personally extremely helpful for people that are experiencing WLD (myself and others) and people whose trees thrive (Jinny, Susanne, Myermike_1micha, Vladimir, Silica, Laura, and others) to share the temperature and amount of light their trees are getting.

The way you would use the app would be to point the camera up at the strongest light source from a representative area of the tree and see what kind of a reading you can get.

If anyone thinks this would be a good experiment to run as a group, let me know and I will kick it off and share the app I'm using.

Thanks to Mike for a great thread!

Hi Mike, I am using 511; and water every week or two. I shouldn’t let them get so dry by two weeks, but sometimes I am distracted or busy.

Its really not all that technical. If your tree is experiencing WLD because the leaves are receiving too much light, while the soil is too cool, just place a towel in between the tree and source of light and the WLD quickly stops. Or you can simply raise the soil temperature to 70-F or higher too match the light level and the WLD quickly stops.

Silica That is what I do I insulate the soil on top to prevent evaporation cooling in a room of 70F. It is not perfect because leaves drop for other reasons.

The medium of every container tree I have is covered with a fabric cover manufactured by Root Maker Corporation. They are called Root Caps. You can see them on the below link.

https://rootmaker.com/retail/28

Steve, how do you cover/insulate the soil? I see the RM root caps are fairly low cost, so I will consider those, too. I am also in my first year using 511 mix, so comments on how that affects things, is welcome.

Your root caps is much more sophisticated than my grape size wads of old newspaper pieces I use for my taller trees and the base of my reflector buckets for the shorter trees. It probably work better than mine if others want to do the same for their trees.

the 5-1-1 mix hold so much air that you don't have to worry about oxygen loss to the root so it is safe to cover the soil with a sort of vapor barrier insulation cover. I get lots of corrugated cardboard that I could cut to size and place over the soil.

The top light bucket touches the plant bucket so there is no evaporative loss from the surface soil. The bucket to the right rests on the edges of 7 plastic 1 quart seedling meiwa kumquat trees . The water drips down from the light bucket into the cups and the trees were planted close to the edge of their cups so the trees would grow up the bucket's side wall on past the light bulb without touching and getting burned. Not much evaporation from these seedlings.

Great thread. I’m happy to contribute tomorrow...tired out tonight. I have some WLD, but nothing major. Some trees lose more than others...go figure. I also have them at various locations with varying light and temp levels and can chime in on that also. Night guys!

The reason I suggested the light meter readings was that I suspect I may have the opposite problem of most WLD folks - not enough light and roots too warm. My plants are probably 65-70 most of the time and I water lightly with warm water, so I'd be shocked if the problem is too much light and cool roots. My leaf drop also started 2-3 weeks ago, as we approached the winter solstice. But since my plants are already under what I consider to be a fairly serious grow-light setup, I think it would be interesting to compare how much light my plants are getting with some of the more successful growers.

PacNor, why do you water lightly? Trees don't eat they drink. In what medium type are your trees growing.

There are many reasons why citrus drop their leaves. Environmental factors such as high temperatures, wind, low soil moisture, low relative humidity, nutrient deficiencies and high soil salinity can cause premature leaf drop. Other causes are disease, pest problems and scion rootstock incompatibility.

Silica is correct. There are many causes of leaf drop which, as I said above, will make it impossible to find an answer to Mike's question:

What' light' 'temp' ratio is provided to your trees to avoid 'WLD'?

because it is not just the "light' 'temp' ratio" but many other factors that are responsible for avoiding leaf drop.

Silica, I described my watering as light for two reasons - firstly, I do water somewhat less heavily in winter, as my trees are much less active and I can go 14+ days without having to water. Second, because typically on the citrus forum if you mention a problem someone will jump in and tell you that your soil mix is wrong and that you water too much :) The tree dropping leaves is in a porous, quick-draining mix of 50% bark-based potting soil and 50% growstone media. I water heavily in this mix in the summer and the tree does well.

I don't think I or anyone else is over simplifying all indoor citrus problems down to a simple light to temperature ratio, and I'm not sure it's fair to categorize Mike's post or my comments as such. It's likewise completely unhelpful when folks whose trees are struggling get told "well, it could be anything". If we don't eliminate potential causes or figure out what makes some members so successful, we don't learn or grow.

I mentioned above that I consider not enough light to be the most likely cause of my own trees' leaf drop, especially since it began in earnest near the shortest day of the year, and I wanted to confirm that by comparing with others. If I am giving my trees more light than others are, then I know it's not insufficient light and I can play with temperatures. There is absolutely value to collecting an aggregating data from as many members as possible to identify trends. Even if what we learn from collecting data is that light and temperature are not correlated, there's value to that as it will cast doubt on the whole WLD theory.

PacNor, your post is interesting. No one said growing container citrus is simple. However, there certain growth factors that seem to cause more problems more often then others. Please tell me what is growstone, I'm not familiar with that term. .

Hi Silica, growstones are a pumice or perlite alternative made from recycled glass. They're very light but don't float to the top like perlite and they come in larger / coarser particle sizes than the perlite I can source locally.

growstone.com/the-data/faq/  <-- This is their website so it's obviously 50% marketing, but lots of good information to be had also.

Pac, I know EXACTLY what you are saying and that is why I started this thread..

This is a fact according to my trees and my experience..I have been growing citrus trees since I was 12 years old and it use to be my watering techniques that would cause leaf loss and kill them by the end of winter until I too start using good porous mixes..Then it was not enough watering because it took me time to get use to the mixes I was using. Then it was BUGS, in particular spider mites...

Once I got all possible factors under control this I never thought of and learned is also another major cause of leaf loss and death of my trees,that how much light is provided or how much less can have a huge devastating consequence if not provided in in as close as a balanced way that we can.

LIGHT and TEMPS have caused the biggest problems for me in the past after I got everything else under control. I would still loose a ton of leaves, branches and twigs and I had everything else right. Why?

Well after spending years here and talking to many garden masters, it was them that pointed men in the right direction about how to avoid leaf drop from a lack of sunlight and how temps play a key role in the darkest days of winter.

I was told to keep my trees at LOWER temps to avoid massive leaf loss and even death if I could not provide at least 12 or more hours of direct sunlight and or artificial lights... I decided to give it a shot and stick them all on my cold porch during the winter which prevented WLD in one season! I even tested this by placing one of my huge Orange Trees into a much warmer room 70 or warmer in a south facing window , actually the same room all my trees are in now, and what do you know? That tree lost half the leaves and branches in less than two weeks of putting that tree into warmer conditions...So I stuck it back out on that cold porch, and it stopped that day!

Then the only trees that drop leaves on my like that are the only ones I stick in the window, south facing in a very warm room. 80's by day, 70's by night. Not only do they drop leaves like crazy, they get mites from a weakened state. Once I opened my windows in there and cool the room down dramatically, the leaf loss stopped..

The room in which I keep my trees in now have not had one problem with leaf drop or branch loss until a few days ago when I accidentally left the door open and warm air flooded that room. I loss an entire mass of leaves on one tree, a huge drop of leaves on my Orange Tree and branched on a Lemon Meyer. So once again I closed that door and temps dropped down into the low 50's and the leaf loss has stopped.

So yes, Temperature and the Ration of light provided to our trees is just as important as anything else, and yes I found my answer. It is hoped that many here will find this answer after trying everything else..

Your problem is not unique and in fact very common, so you are right...If you show me how to try that app, I will for you and anyone else who thinks they can benefit from this..

Pac, I can bet you this..If some here did not have the nice greenhouses they are using which provides lots of light, or did;t use the expensive lighting, they too would consider lowering their temps to prevent 'WLD'...

I cal also make a bet that if I allowed the temps to rise over 70 in my tree room at this time of the year with the sun at its lowest angle, even with what lights I can provide I would loose ALL my trees to WLD at mites after that of what's left..

Pac it really is common sense...You don't have to even be a professional gardener to know that if any plant is left in a sunny window and not rotated often, one side will suffer while the other thrives in warm conditions.

PAC. Here is the leaf drop from my favorite tree with one day of very warm temps in there.
Once the temps were allowed to fall under 65 in fact into the low 50s all leaf loss stopped. I kept the canopy intact thank God !

Might I add that my local nursery keeps all their hundreds of citrus trees in their cold room to avoid leaf loss and pests....Temps in the lower 60's.

I might also add that I have NO Leaf loss or 'WLD' on any on my citrus trees kept in my very b right greenhouse with temps always above 60 at night and 70;s by day! Avery different story there..))

The absolute main cause of WLD is growing citrus trees where they don't really belong like pots and indoors.

Steve, do the trees you grow in buckets under those lights get massive leaf loss? Twig die back? Branch die back?

Do the ones you grow in your colder glass addition structure get massive leaf loss and or twig/branch die back?

Thanks

Mike

The trees outside do not loose leaves. The trees inside do not loose leaves except to spider mites and aphids. My grafted trees seem to loose leaves over many weeks. My new Fukushu on C35 is the only tree I have that lost most of its leaves in a day. I was very irritated at the leaf loss. I have never had twig die back on any citrus tree except the -3F meiwa kumquat.

Steve

Steve, I see by your set up and the warm temps that you keep them at, you are doing a great job! Look at all the light you provide in such an intense way! It's no wonder yours grow so well in warmer temps under such bright lights!

Then your trees outside get much needed direct light as such like a greenhouse and in which you have done a fantastic job there too. Bravo

Hi guys! Mike, my sunroom is about 69 F at day time and can go couple degrees lower at night, if it's sunny day outside, it can get warmer and plants get about 5 hours of direct sunlight. Unfortunately this month we got too many days of dark, gloomy days in a row, the plants definitely don't like it. Very cold outside now and snow drifts on my balcony

Here is the dying branches of the tree I mentioned:

Here is the lemon branch of it:

Mini rose :) (rescued)