Our palm landscaping on our southwest side yard was installed last Friday -- a sago, an xButiagrus and a Sabal minor. Despite watering, I started to notice rusty brown spots on our mule and some discoloration on the sago. Today the coloration was really noticeable on the sago, and similar to the mule's.

Sago before:

Sago today:

Spotting on the mule:

The interesting thing we noticed about the plants in question was that the rusty spots appeared on the side of the leaves facing our house, not on the fence side. At this time of year the sun travels more or less from left to right across the side yard and is positioned high in the sky across from our house. So the side of the affected palms was opposite the sun.

Right now we are convinced the plants are being burnt from the sun's rays being reflected off of our low-e windows. The double paned, low-e windows focus the beam of light into a concentrated area (can be seen by the bright somewhat X pattern of light hitting the pavers or sometimes seen on the house across from ours). This concentrated area is much hotter than the rest of the reflected light and you can easily feel the difference.

Over the last few years I had heard of low-e windows' concentrated heat melting vinyl siding on the houses across from the windows if the distance between houses and the sun's angle accidentally provided the right focal length. Remembering this I did a bit more research tonight and saw that this wide spread problem has affected not only vinyl siding but house paint on wood by bubbling and peeling, grass browning and artificial grass melting, furniture material melting and of course landscaping material being scorched. It's caused all kinds of problems for builders, material suppliers and neighbors who find themselves affected by a neighbor's low-e windows. This is something that I NEVER thought about when planning our landscaping project.

We are now trying to figure out how to save our sago and mule from ugly scorch marks and future damage. We're going to call the window manufacturer and see what they say about remedying this issue. Hopefully this thread will serve as a reminder of landscaping issues you can have from the least expected things. So if your sago, etc. isn't doing well in the sun, check out the sun pattern from yours or your neighbors' windows and look for what has become known as the "Death Ray".

Here are a few links you might find interesting. The first link has a video that shows this "Death Ray" moving across an outdoor sofa and melting the fabric. The second link talks about landscaping around low-e windows. The third link has a video interview with a Vegas hotel guest illustrating that even humans can fall prey to it.

http://www.azfamily.com/news/9pm-extra/Energy-efficient-windows-blamed-for-scorched-furniture-165740456.html

http://www.mdvaden.com/landscape_windows.shtml

http://www.nbcnews.com/id/39403349/ns/travel-news/t/death-ray-vegas-hotel-pool-heats-guests/#.UdPLlRY5vdk

Well this was encouraging...a call to our window manufacturer may get the problem resolved. They have a Full Lifetime Warranty for original homeowners and they told my husband that if the window glass does warp causing a problem, as opposed to normal reflection, they will come out and replace it for free (including labor etc). We need to provide the serial/sales order info (inside window frame) and they will come out to verify the issue and make any replacements as needed. Hopefully our windows are the model that can be removed and replaced from the outside.

In the meantime, we've rigged protective screening in front of our sago area.

Here's a photo I took a while ago while taking pics of our palms and pergola showing this concentrated light/heat pattern on a neighbor's house. We remember standing in the X light pattern on our pavers a little while ago and the area of the X is extremely hot.