Q: My Navajo Globe Willow tree leaves are yellow instead of green. Should I be concerned?
A: There could be several reasons why the leaves are yellow. This time of year, when the leaves have just emerged, they may look a little yellow or light green. This is normal. In another month, they should be a darker green color. If your leaves are yellow with green veins, there is an iron deficiency. Apply an EDDHA iron chelate. Yellow leaves can be a sign of too little or too much water. Deep water down to about 2 feet, and let the soil dry out for awhile. Shallow irrigations do not promote good root growth and can compromise the health of the tree. When the weather heats up, do not water more than weekly, and every two weeks is adequate for an established tree. Water more, and also deeply, if the tree is under a few years old. Also, many of us plant our trees over caliche (or sometimes called hardpan, a hardened deposit of calcium carbonate that makes a cement-like layer combined with the soil) where deep irrigations can sit on top of this material and saturate the roots. Then what do we do when the leaves turn yellow and we do not know the roots are sitting in water? We water more, which is what we should not do. Yellow leaves also could be a precursor for frothy flux, which is a froth-like sap oozing from cracks or wounds in the trunk.
Q: I have just moved to the Kingman area. How do I find out what plants do well here?
A: This question was asked at the Container Gardening Workshop on April 14. There are many articles and publications that are available at the University of Arizona Mohave County Cooperative Extension office at 101 E. Beale St.
A couple of examples available at the office and online are "TIPS for Successful Gardening in Mohave County-Kingman and Golden Valley Areas." This article is available at http://extension.arizona.edu/mohave under "Publications" on the main Web page. Another publication is called, "Landscape Plants for the Arizona Desert," available at www.amwua.org for water conserving landscape plants. Also, look around your neighborhood and if you like a plant, ask your neighbor what it is and if it does well for them. When you go to the garden centers and nurseries, look at what temperature the cold hardiness is for the plant. If you are in Kingman, it should say 10 degrees or less. If in Golden Valley, 15 degrees or less and if at a higher elevation, less than 10 degrees.
Q: I walk my dog every morning and frequently see water from grass irrigation running down the street instead of staying in the grass. Why?
A: This water will eventually evaporate, so it is extremely wasteful and costly as it is not going onto the lawn as intended. If you irrigate, please check to see if your system is operating properly. If you need assistance on how much to water and ways to prevent run-off, leave a message for the master gardeners at the University of Arizona Mohave County Cooperative Extension office at (928) 753-3788, and one of the Master Gardeners will call you back (we pick up calls on Tuesdays and Thursdays). Or you can stop by the Mohave County Cooperative Extension office at 101 E. Beale St. on May 12 to ask the Master Gardeners any question between 9 a.m. and 12 p.m. on "Ask the Master Gardener" day.
Q: When should spring flowering shrubs be pruned?
A: We generally think of pruning in the winter and spring to remove dead and diseased wood, to contain size and to improve the overall health of shrubs. However, many early spring flowering shrubs should not be pruned this time of year because their flower buds get set in the fall and blossoms can be lost. Some examples of these are red leaf photinia, lilac, hawthorn and mockorange. Others like butterfly bush, crape myrtle and honeysuckles can be pruned.