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Monday, September 12, 2011

Yellowing in Palms Can Be Lots of Different Things

This is California fan palm with cold damage from
temperatures in the low 20's or high teens F
Q. We have a fan palm where the palms are turning yellow and I'm assuming dying. One or two would be acceptable but we are have 5 and 6 that are going bad.

A. Let's cover some ideas about why your palms could have yellow fronds. These are the main reasons: older fronds are dying from natural causes and should be removed; fronds were damaged during winter freezes; too much water applied too often or too little water; palms planted too deeply; palms planted in heavy soil that doesn't drain well; palms planted with pure sand around the rootball; fertilizer problems such as iron, manganese or zinc.

Not totally sure on this one but it was probably
light cold damage on this date palm during the
 winter in low 20's
Palms should be planted with the soil taken from the hole plus 50% compost and a starter fertilizer high in phosphorus added. Palms should NOT be planted with their root ball surrounded by pure sand in the planting hole which is commonly done in Las Vegas. The idea of doing that is absolutely crazy.

Palms are high water users even though they tolerate high temperatures and our desert climate. Different types of palms require different amounts of water. The larger the palm, the more water it will require. Some of the highest water users will be date palm with their huge canopy spread. The amount of water will vary but most fan palms would be happy receiving about 20 gallons every time they are irrigated.

This is Queen palm, not a good palm for the hot desert
and probably lack of soil preparation or watering too often
or both
One of the common problems is irrigating palm trees with small amounts of water, like ten or fifteen minutes of drip irrigation, daily or even twice a day. Watering like this can fill the soil with water and suffocate the roots causing them to rot, diseased or both. So if you are irrigating your palms daily, don't do that anymore!

During the heat of the summer they can be irrigated two or three times a week, using 20 gallons each time you irrigate but the soil must freely drain the water away from the tree. In the wintertime you might be dropping your irrigation to 20 gallons every 10 days or perhaps even as long as two weeks.

Sometimes the soil lacks certain types of minerals that palm trees need. Deficiencies like iron and manganese usually appears as a discoloration in the fronds at the center the canopy, the most recent growth. This can range from light green to nearly yellow. If these inner fronds are yellowing then we can usually narrow this to watering too often, poor drainage or a lack of minor elements such as iron.

Center fronds, youngest, demonstrating yellow growth
which could be due to watering issues, soil issues
or possibly disease

Next February when you make your annual application of fertilizer use a complete fertilizer such as a Miracle Gro, Rapid Gro, or Peters. You can also use fertilizer stakes. Make sure it is well balanced and try to select a fertilizer with the three numbers the same or close to the same value like a 16-16-16 or 10-10-10. Add an iron chelate that contains the EDDHA chelate in the ingredients. Let's see if that works along with irrigating with a large volume of water but doing it less often.

Cold damage on palms usually results in the older fronds turning a bronze color first and then browning later as they die. General rule of thumb is if more than half of the frond has turned brown, remove it. The new fronds at the center of the palm should be healthy and green when they emerge in mid-spring.

If your soil is heavy and holds water a long time then plant on a mound 2 to 3 feet high and 6 to 8 feet across so the water drains away from the roots.

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