QUESTION: With the recent freezing weather we have experienced, will my ash, oleander, and other plants recover from the damage they received?
ANSWER: Yes they will recover. New leaves grow from secondary buds. During the summer they will look normal. Plants that took hard freezes like oleander will regrow from crowns and/or roots. Freeze incidents will occur from time to time causing plants that are prone to freeze damage being frozen back. Saguaros in Cochise County are a good example. The constrictions that you observe on the trunk and arms of the saguaros were usually caused by freezing temperatures. Prune back all of the dead stems and branches on the affected plants. If new growth is coming from a branch, prune back the dead tissue up to the new growth. Many times the new growth will take over and replace the damaged stem or branch.
QUESTION: How can I tell if my apples, pear, peach, cherry, and apricot flowers suffered freeze damage from this most recent freeze?
ANSWER: Most of the fruit mentioned will freeze if in full bloom from 23 to 28?F. To examine a flower or fruit remove one from the tree. Make a horizontal cut with a knife through the base of the flower just beneath where the flower petals are attached. If small fruits have already formed cut horizontally through them also. If in the center of flower or fruitlet seed tissue, found in the center, is brown then the flower or fruitlet is dead. If the seed tissue is green then the flower or fruitlet is alive. If the seed(s) die then the hormonal stimulus that the seed(s) produce which signals fruit growth will not occur, therefore no fruit will be produced. Go around each tree and cut 10 or 20 flowers or fruitlets to determine the percent of survival. If only 5 to 10% of peach flowers survived you will have a crop. If only 10 to 20% of apple or pears survived you will have a full crop. If more survived you will probably have to thin the fruit in a few weeks to produce large fruit. If thinning is not done either by man or Mother Nature's freezes small, inferior fruit will be produced.
QUESTION: The cottonwood in our back yard has several limbs that are dying in the center of the tree. It is growing in a fescue lawn. What is causing this to happen?
ANSWER: Cottonwood trees are native to rivers, streams, and washes in Arizona. They require a lot of water. You need to water the lawn and then deep soak for the cottonwood tree. If you water shade trees with only the 1 to 2 inches of week per water required by the lawn you will not supply the 3 to 6 inches of water per week that large trees will need. This is because lawn roots are primarily in the first foot of soil. The majority of tree and shrub roots will be in the top two to three feet of soil. During the hot summer weather trees will extract large amounts of water from the soil each day. Shallow watered tree roots will tend to be closer to the surface of the ground. However, the genetics of the tree has a lot to do with the depth of rooting. I have known of several cases where the tree roots were growing up to the soil surface and the owners cut the roots out so they would not have to run over them with the lawn mower. By doing this you sever the roots that uptake nutrients and water to specific limbs of the tree causing them to die.