How would a chestnut tree fare in Las Vegas’ desert climate?
Q: Are there any chestnut trees that can grow well in our hot climate and produce edible chestnuts? We would like to plant one in our backyard but wanted to make sure they can take the weather. What kind of upkeep would it require?
A: Good question, but no suitable chestnut trees are currently available. The top two countries producing chestnuts are China and Korea. The United States is starting to produce them, but mostly in the Eastern states because of water restrictions. Most of the chestnut’s native range is cooler and wetter than our hot desert. The most delicious chestnuts are from larger trees. Only female trees produce nuts.
The American chestnut (over 100 feet tall, 13 feet in diameter) nearly went extinct (possibly fewer than 100 left) during the late 19th century because of a fungal blight called ink spot or chestnut blight. This tree is not suitable for our desert for many reasons, including its thirst for water because of its uncontrollable height.
Q: My neighbor wants to convert her front yard from lawn to a desert landscape. She has two 32-year-old pines and an olive tree that she wants to save and is concerned about the conversion. Do you have any advice?
A: When the conversion is done, make sure enough water is applied — and deep and wide enough — and that the conversion is done during fall or winter. If shrubs are used under the tree’s canopy, be sure that enough shrubs are used. The water used to irrigate the shrubs is enough to share with the pine trees.
Both how much water to apply and when to water again are important factors. How do you know if it is enough water? One method is to watch the new plants. Another is to guesstimate.
Guesstimation requires two tools: one is a long piece of thin steel, and the other is a moisture meter. To judge if you are watering deep enough, a thin piece of rebar or a very long screwdriver will work. It will easily push into wet soil if there are no rocks. Find at least three spots near drip emitters and push it into the wet soil the day of an irrigation. Average the three. If the wet soil is not deep enough, increase the minutes.
To determine how often to apply water, I would use an inexpensive moisture meter you can buy at most hardware stores. Again near a drip emitter, push the tip of the moisture meter in the soil slowly so that the tip is about 6 inches deep. After an irrigation, the needle should register “wet.” On a zero-to-10 scale, the meter should register halfway or drier before another irrigation is needed.
Mature pine trees may have problems with the newly applied water restrictions, but not your olive tree. Olive trees will adapt to the irrigation. It’s mostly because of the pine trees’ mature size. Pine trees get much bigger in lawns (45 to 60 feet) than olive trees (25 to 35 feet).
Q: A few plants in my yard have wrinkled leaves on new growth. These include a dwarf Red Rio grapefruit, Wonderful pomegranate and a Thompson grape. All were planted in June. I have not fertilized the pomegranate or citrus at all, and they receive regular water on my timed irrigation. Leaves from growth a month or two ago look normal. What could be causing this and how can I prevent it?
A: Your plants look healthy. We can eliminate any disease problems. The cupping of leaves of several types of plants can be a sign of weed killer damage. That can be an important clue. Several weed killers contain products that can cause leaves to begin cupping when they are young and still growing.
Water and fertilize them and give them a flush of growth when you water. Don’t water them more often; just give them more water when you irrigate.
Make sure you are extremely careful with any weed killers you might be using in the vicinity of the plants. Weed killers can drift with the wind or volatilize when it’s hot. This drift will land on the plant leaves and cause cupping on lots of different varieties.
Never spray weed killers on days when there is even a slight breeze or when it is hot or the ground is hot.
Leaf distortion like that can also be a sign of water stress, trying to set new leaves when the soil is too dry. Make sure the plants have adequate water during times of growth.
Crinkled leaves in your citrus can be fairly common. This can be the first sign that the tree is not getting enough water. Increase the amount your tree is getting, and monitor the frequency of water closely. I would probably water twice a week, deeply, in summer. Perhaps three times if it gets really hot and windy.
Your Thompson grape looks healthy. Some of the leaves are beginning to scorch a tiny amount around the edges, but this is fairly common in our climate. The cupping of its leaves is not that common, though. Grapes are sensitive to some weed killers and will get cupped leaves if the slightest amount of weedkiller lands on them. There is really no disease or insect that could cause this cupping on grape. However, it is only on a few leaves, and I would not worry about it. The damage has passed. Water and fertilize it.
Lastly, your Wonderful pomegranate: This kind of distortion can occur at cooler times of the year when aphids are present on the leaves. Whiteflies are a problem on pomegranates and could also cause leaf distortion along with some stickiness on the leaves. Unlike aphids, which disappear when it gets hot, whiteflies love the heat and persist through the hottest times of summer. Look for them on the bottoms of the leaves.
Usually soap and water sprays every few days help control whiteflies but never really get rid of them. Control is an ongoing process of spraying with soap and water sprays, Neem and other sprays recommended for pomegranate and fruit trees. This might also be a sign of a lack of water when it was setting leaves, but based on the amount of new growth, I kind of doubt it.
Bob Morris is a horticulture expert and professor emeritus of UNLV. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.