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Monday, September 12, 2011

Italian Cypress Browning Not a Good Sign

Q. Help! My Italian cypress are drying out and dying mostly from the top down and they have their own bubblers for water.

Italian cypress with foliage browning
A. Major reasons for Italian cypress dieback: Too much water. Water deeply once 3 - 4 weeks in winter and no more than about once a week in summer. Too little water. Sometimes people put these trees on just a few minutes of water from their drip irrigation system. Water should be applied so that it wets the soil down 24 inches to an area at least four feet in diameter around the tree. Depending on how quickly enough water from your drip system is applied this might take up to several hours of applied water.

Spider mites. Starts in hot weather because that’s what they like. Usually a problem on trees that were underwatered. Spider mites like dirty foliage. Wash trees with a high pressure hose nozzle after dust storms or a couple of times a year just to keep them clean. Periodic soap and water sprays are not a bad idea either.

Webbing in italian cypress may or may
not be due to the bad guys

Borers. Several people have reported borers in Italian cypress but this has never been a common occurrence in the past. I could not find it reported anywhere else either. Usually a soil-applied insecticide for borer control applied around the roots would be recommended if this were the case. Get your irrigation under control and that should solve most of the problems.

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.

Moorpark Apricot a Good One for Las Vegas

Apricots on short shoots called spurs
Q. We have a beautiful 5-year old Moorpark apricot tree. It has grown well and looks quite healthy. However, it seems to put out a sparse array of blossoms in spring and has a very light crop of fruit every year. The fruit is delicious. I read that the chill factor for this cultivar may be higher than our climate provides. Can I increase the chill factor by watering the branches in winter on cool days to lower the tree's temperature and thus increase the chill factor? If successful I could get a larger crop?

A. Moorpark is a wonderful apricot variety and is used extensively in the canning and fresh fruit industry in California. It is best if it receives about 600 chill hours during the winter. This means that the temperature should drop below 45F for at least 600 hours for the best fruit set.

Apricot branch in the winter
with spurs clearly visible
However, don't worry about the chill factor in this case. We have Moorpark and it has good fruit set here even after 18 years at our chill hours. The problem is more likely the fruiting spurs or lack of them. These will be the short branches along the major branches.

If these were pruned off, damaged or never developed then the crop will be light due to a lack of flowers. This year was a bad year for apricots. We had good weather and then it turned very cold in March. That freeze reduced our orchard apricot production from about two tons down to about 200 pounds.

We have had no problem with Moorpark and irregular production and it has been a wonderful producer in most years. Perhaps the location of your tree in a particular microclimate of your landscape or how it has been pruned may have more to do with it than the variety itself. But a lack of chilling is not the problem.