Xtremehorticulture

Xtremehorticulture of the Desert

Arizona Rosewood Dying

Leave a Comment / desert native tree, disease, insect /

 Q. I live in Oracle, Arizona, and my 15-year-old Arizona rosewood has some dying branches in it. Not the Arizona Rosewood mentioned in the question but it is used in Las Vegas landscapes. A. Dying branches usually indicate a water transport problem, mechanical damage, diseases, chemicals or borers. Arizona rosewood is a 12- to 20-foot-tall xeric tree native to the Sonoran deserts. It is considered a lower water use alternative to oleanders. Arizona rosewood is so new to the landscape industry (less than 30 years old) that not much is known about it. This may require some detective work on your part. It should start to flower and produce small fruit between 6 to 8 years of age so your tree should have started flowering nearly ten years ago.             It is in the rose family so check for damage from borers and fireblight. Other disease possibilities that may include single branch dieback include verticillium wilt.             Even though this is a xeric plant and can handle less frequent applications of water, make sure water is applied deeply and occasionally during the summer particularly during dry periods. Water applications should be about four times each year, particularly during the hot summer months, and to a depth of about 18 inches. The water should be applied to at least half the area under the trees canopy.             There is some discussion about its potential sensitivity to landscape weed killers. Make sure nothing was used close to this plant.

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Pruning Lantana

Leave a Comment / summer pruning /

Q. My lantana is about to eat my house! They are 15 to over 20 feet wide each. My neighbors’ lantana are only about 4 feet across. Mine are much too large for the space given to them. Should I cut them back now? Not the lantana written about but to give you a look if you don’t know it. A. You can cut them back now to about an inch. It will leave the area bare and twiggy. There is time for them to grow and fill out again. If you have the time, selectively cut back the bigger diameter stems and leave the smaller ones closer to center. This will leave the newer flowers but reduce its size.             If it does not freeze it will grow from its terminal or side buds and get big. Next year cut it all back to an inch of the soil in early January regardless of whether it freezes or not. This will contain its size. Your neighbors’ plants were probably cut back during the winter.

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Borer Prevention

Leave a Comment / borers, fruit trees, prevention /

 Q. I have lots of borers in my trees. What can I do to prevent it from happening? When borers are a problem it starts about mid summer. Often it begins in parts of the tree frequented by our intense sunlight like the upper sides of limbs that are not shaded. A. First, prevent sunburn to all trees, particularly young fruit trees. Sun damage is a problem immediately after planting in our desert climate. Damage from the sun can lead to borer problems later down the road. If I were buying a fruit tree, I would buy a small tree and let it grow as a bush. This way the lower limbs will shade the trunk. Let the Tree Grow Bushy As soon as it starts to produce fruit, that next winter, I would remove the lower limbs only so the fruit does not touch the ground. Leave as many of the lower limbs as possible to shade the trunk. In fact, let it grow into a shrub. The biggest mistake homeowners make with fruit trees is to buy large fruit trees with limbs high off of the ground. If lower limbs are present, they are removed to make a tree. Buy smaller trees and let them grow to the next size. Shade the Trunk It may be the right thing to do in other climates but not the desert. Desert fruit trees need tender trunk protection from the sun to about five or six years old. If you have a fruit tree and it is “limbed up”, then protect the trunk with diluted latex paint, tree wrap or protective collar that shades it. A sign for a borer problem is limb death in the middle of summer; brown dried leaves clinging to one or more branches on the south or west side of the tree starting when it is hot. Use a borer soil drench with an approved pesticide for borers. You are not permitted to eat the fruit until 12 months have passed. This particular pesticide is best applied after flowering. Use a Pesticide as the Last Resort There are pesticides that can be used that will kill borers still in the tree. Be careful. Treat trees after they finish flowering to protect honeybees. Don’t eat fruit from that tree for one season of production after you apply a pesticide. 

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Joshua Tree Survival After Transplanting

Leave a Comment / joshua tree, landscape, yucca brevifolia /

 Q. We have a few Joshua trees on our property. We planted three more that were relocated from Arizona and had the proper permits. They didn’t do well so we dug them up and saw root rot. Does it make sense to cut away any damaged rot? Or perhaps you have a better suggestion all together. Joshua trees taken from the desert should be small or established in the container before planting. A. My experience with native Joshua tree survival after transplanting is that the larger the tree, the poorer the survival. The biggest reasons for lack of success were watering too often and poor soil-water drainage. Smaller plants in the desert are capable of surviving relocation better than larger well-established ones. Survival “tricks” were used sometimes when relocating plants such as orientation and soil additives. Some “tricks” made “sense” such as removal of a portion of the plants top to compensate for root loss and improve transplant success. Outside of orientation and soil additives, how are size reduction “tricks” done to Yuccas? Super Thrive is a well known additive that makes claims for improving transplant success. Some people swear by it, others swear at it. The Smaller the Plant the More Success Native plants have a very wide and established root system. Big native plants look beautiful but are exceedingly difficult to move from the wild primarily because of their established root system. The same is true of established landscape plants; smaller ones are easier to relocate than larger ones. Larger native plants like this Joshua tree has had limited success reestablishing in a landscape unless it is well rooted in the nursery. The best luck planting is with plant Joshua trees less than three feet tall that were established first. The best survival was with those under three feet in height. Dip the roots and lower stem in a Bordeaux paste and let it dry before planting. This gives cacti some protection from watering too often. Amend the soil at the time of planting and stake them if needed. Water at first planting and then every three weeks until they have rooted. 

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Pruning Navel Orange Tree

Leave a Comment / citrus, Satsuma /

 Q. Do you have any recommendations for pruning our poorly maintained ‘Navel’ orange tree?  The main trunk has grown to about 34” from the ground and leafed and branched out.  Last season a “sucker” shoot sprouted from the side of the truck and wasn’t pruned out.  Now it exceeds 8’ but seems extremely happy.  Get rid of that sucker from the rootstock! A. That sucker is part of the rootstock and not part of the tree. You don’t want it to stay. It should be removed when you first saw it. See how the leaves growing on it are different looking from the Mother plant? Not only that, the growth from it was so rapid the crotch makes a narrow letter “V”. It will not support the weight of itself, plus its fruit, as the tree gets bigger. Narrow crotches can support much weight. They make the letter “V” and good crotches make the letter “U”. This type of branch will split from the tree. Not only that, this unwanted growth “robs” the rest of the tree from “food” that it makes as it gets larger and denser. What wasted growth! Remove this sucker now and don’t leave a stub attached to the trunk when you do. It should have been removed when it was first seen. Remember, if growth is a size that hand pruners can remove, then do it anytime! Early Freezing Weather Makes Fruit Drop Early             The most likely reason your fruit has fallen from the tree was because of early winter and spring freezes. The flowers froze, unpollinated, the fruit then died and fell off. This result can change from year to year depending on early spring freezing temperatures. Citrus in General Not a Good Choice for Freezing Climates             Keep in mind this is a ‘Navel’ orange and not the best choice for our Las Vegas climate. A better choice would be a ‘Satsuma’ orange (tangerine) because of our cold winters. The tree can still lose fruit due to early spring freezing temperatures but at least you won’t lose the whole tree! However, placement in the right microclimate for either orange type, ‘Navel’ or ‘Satsuma’, may make a difference. For ‘Navel’ orange place it in the warmer microclimate of your landscape such as a south or west side. It needs protection from winter cold to survive. The more cold tolerant ‘Satsuma’ would be placed in a colder microclimate, such as the north or east side, of the landscape. This placement delays the flowering of this tree as long as possible. Your choice with which you want to keep but my vote is for changing to a Satsuma.

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Prune Larger Shade Trees to Save Water and Be a Good Neighbor

Leave a Comment / African sumac, fruit trees, how to prune, pruning large limb, removing large limbs /

 Q. I have a 20-year-old African sumac nearly 30 feet tall which provides great shade in my backyard. It needs another pruning when it cools off. I did a major cutback last fall at the request of my neighbor because of leaf drop. Any suggestions on how best to do so and keep the shade and cooler temperatures it provides? Drop crotching an African Sumac that is too tall will save water. A. Two things you need to know if you are doing this yourself; drop crotching and how to do a 1-2-3 pruning cut. Stand away from the tree so that you can see all of it. Identify the limbs giving you the problems. Trace the limbs back to a lower crotch. A crotch is where at least two limbs come together. This is where the pruning cuts and lowering will be done. In a 1-2-3 cut the first cut is made 12 inches from the tree trunk and upward to prevent a large limb from pulling the bark from the trunk Make a 1-2-3 Pruning Cut During cooler weather remove the limbs that are offensive. Use a 1-2-3 cut to avoid stripping the bark from the tree. A 1-2-3 cut is done first by making an undercut six inches from a limb to about 1/3 of its diameter. The second cut is made outside of the first cut. Attached bark may strip down to the undercut, or first cut, so the falling limb will not tear the remaining limb and tree trunk. This is why the undercut is made first. A third cut is used to finally remove the remaining stub. It is a finished cut. The third cut is the smallest cut made that removes most of the stub remaining so the cut heals faster. If you have never done it, for safety reasons and a better-looking tree, hire a certified Arborist to make these pruning cuts so that it will make the tree smaller and keep it beautiful. Part of your payment is for decisions that result in a prettier tree than you could have done.

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Fall Vegetable Planting Use Your Phone App

Leave a Comment / cool season vegetables, fall planting, Hot summer, predicting when to plant /

 Q. Because of the continuing heat through September, when would we plant vegetables for our home gardens. What veggies would you recommend for the first planting? Ideal vegetable seed germination temperatures oriented for spring planting when soils are colder. In the fall soil is warmer and gets colder. For fall gardens work backwards with this chart. A. The Fall planting season is always uncertain. Weather phone apps help our guesstimates for about two weeks.  What is seen on vegetable planting lists are averages of the planting dates for that season. For each season you should look at the 10 or 14 day forecast from your phone app. Fall Means Cool Season Vegetables In the Fall the focus is on planting “cool season (winter) vegetables”. Its kind of a misnomer because there is no such things as “cool season” and “warm season vegetables”. That is a human invention to categorize the vegetables we eat. Plants grow best along a continuum from 45 to 90F. Some plants grow better during cooler weather and others during warmer weather. Humans divided vegetables into these two groups. This weather phone app is typical for Pahrump, Nevada. https://pvtimes.com/wp-content/uploads/2017/12/web1_1007-weather_7153434.jpg Use Your Phone App Use your phone app to pinpoint when to plant by looking at the following ten days of weather. Let’s use sweet corn as an example. Soil warmth isn’t a problem in the Fall like it can be in the Spring. Sometimes during the Spring, the soil must be warmed first to get growth from some of the warm season veggies, like tomatoes, peppers, eggplant and watermelon.  In cooler soils they just sit there, wonderful-looking, with no growth. Work Backwards We are now transitioning to the “cool season vegetables”, so a warm soil is a blessing for them. Again, not like the spring with its cooler soils. Start with the so-called “warm season vegetables” first. Because we are planting in the Fall, start at the middle of the chart I attached and work backwards for planting times. Remember some cool season vegetables have a long production cycle (like sweet corn as an example). On crops with a long production cycle, plant early in the late summer and use varieties that have a shorter production time (like those varieties that are harvested in 60 to 75 days)! Save Germination Time Due to Warmer Soil Because you are planting in the fall when soil temperatures are warmer you can normally subtract five days from the production time on the packet (e.g., instead of 70 days for production, use 65 days) if you get it in early enough and wind is not a problem. Using 70-day sweet corn as an example, guess at the harvest date (say Nov 15). Plant in 65 days less than that (approximately Sept 10). It’s still a gamble that far out but can be worth it!

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Differences Between Xeric and Mesic Plants

Leave a Comment / landscapes, mesic, shrubs, trees, xeric /

             Many homeowners don’t know the names of plants in their yards or landscapes. Most can look at a plant and know if it is a tree, shrub, or flower but not its name much less how often it should be watered and with how much. This pyracantha was known as a “plant with berries” to a homeowner trying to calculate its landscape water use. Pyracantha does have berries but it is considered “mesic” in its need for water. Xeric plants vs Mesic plants Lower water use trees, shrubs and flowers are watered less often. They should get the same amount of water when they are irrigated but don’t need it as often. That’s how xeric, or lower water use, plants operate.             One way to find out if an unnamed plant is xeric is to water it less often during the cooler months. In the long run xeric plants are watered less often. That’s how they, and you, save water in landscapes. If it starts looking bad to your eyes or dies, then it is most likely not xeric. Big Trees are Seldom Xeric             Another method is their size. Big trees are seldom xeric. Xeric plants are not big. They tend to be smaller. The bigger xeric trees and shrubs grow where water collects; arroyos, waterways, and desert springs. This young shoestring acacia is a 40 foot tall mesic tree from Australia that grows along waterways. This shoestring acacia was “topped” (not done that well I might add) probably because it was getting too tall for that spot. Shortening its height will reduce its water use but not how often it needs water. Big trees use more water than smaller trees. This is true even if you buy one that is small and it grows big when it gets older. Just like kids. You don’t know if your child will become tall or not until they get closer to that size. Oh wow…which side of the family did HE/SHE come from? How to Reduce Water Applied to Your Landscape             During these cooler fall months, start watering less often and see what plants start looking not so good. Try adding more drip emitters to those plants looking not as good as you are watering less often. This gives these plants more water but still less often.

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Remove All Roots of Palms During Removal?

Leave a Comment / coir, date palm, soil mix, sucker /

Q. We have decided to have our Mexican fan palms removed. Do we need to have all the roots removed or just cut the palms down to the ground, especially the one next to the pool? Suckers from palms such as date palm are oftentimes removed when they get larger.  Success rate depends on taking a small amount from the “mother” palm as well as the sucker. A. If your palm trees do not sucker from the base (date palm, Mediterranean fan palm do produce suckers from the base) then as soon as the top is cut off, the palm will die. Both Mexican and California fan palms have one central bud at the top which is the only place where new growth can occur. Once cut and they die, they will slowly decay if left behind. Suckers from date palms are usually removed when bigger. Palm “Wood” Rots Very Slowly             The problem you will have when you leave any kind of stump is the palm trees very slow decay rate. Palm debris decay or rot very slowly. Coir is taken from coconut palms and is used in soil mixes to build soil structure because it resists decay. It is slow to decay and is the main reason I discourage its use in compost piles or use in woodchip mulch. It makes a great semi-permanent component in soil mixes. In both cases you want fertilizer or compost added to circumvent its slow decay. When plants decay, they add to the organic content of the soil and help make it darker. Coir is an ingredient we use in our soil mixes at our farm in the Philippines. Why? Because it is available and cheap. Remove as much of your palm trunk as possible. The palm roots won’t regrow, but any debris left behind from the trunk will decay very slowly. If you decide to use it in your new soil mix (it is a great addition to soils to improve soil structure), chop it as small as possible and make sure that fertilizer or compost is added to the soil to compensate for the slow breakdown of palm debris. By the way, water from pools is not all that desirable by any plants if they are getting enough water from irrigation.

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Elephant Ears Not an Easy Choice for the Desert

Leave a Comment / alocasia, colocasia, desert, elephant ears, taro /

 Q. What went wrong after I planted Elephant Ears (Colocasia spp.) in my back yard planter? I planted Elephant Ears last summer and at first it appeared to flourish. Very soon thereafter it began to wilt and appeared burnt. Then of course it died. The planter is covered in river rock. The irrigation to it, I believe, was sufficient for the plants. The planter also holds one lemon tree and two very tall queen palms, and they were fine.  I was wondering if the river rock created too much heat? Taro (Colocasia esculenta), called gabi in Filipino, as it appeared at our farm in Batangas, Philippines, is a close relative to Elephant ears (Colocasia spp.) Elephant ears is an ornamental type grown for its big “ears” or leaves. A. The river rock had nothing to do with it. Colocasia or elephant ears has a lot of things going against it in this climate; it is tender to any kind of winter cold, it is an understory plant so it does not like direct sunlight, desert soil doesn’t have enough “organics” in it so it must be amended, and the soil should stay moist because it likes wet areas.        This particular elephant ears is a close relative to taro and yam. Another plant closely related to it is Alocasia spp., which also has big leaves and is sometimes called elephant ears as well. All elephant ears require a lot of babysitting in our desert climate because they are really tropical plants. Just Because its Tropical Doesn’t Mean it Cant Grow Here The best spot for it is in partial or filtered shade, planted in soil high in “organics” and kept moist. Move it into a garage when winter freezing temperatures threaten it, similar to banana and plantain. Elephant ears is grown for its roots and leaves, not flowers so it can grow in lower light levels than fruit trees like lemon. Sounds like a lot of work to me. It did well in the spring and would do well in the fall because of cooler weather, but struggles during our hot, dry, windy summers, and freezing winters. Lemons have a better chance. ‘Meyers’ lemon tolerates some freezing winter cold temperatures better than other lemons. Queen palms don’t like our dry winds. They get ‘ratty’ looking. If you want to try it, grow it only on the north side of a home in bright sunlight under shade cloth. Amend the soil with compost. Keep the area moist as it will not like dry soil at all. You must address all these problems; cold winter temperatures, amend the planting soil, provide a location where it can get as much protection from the sun as possible without a lack of it, keep the soil moist and windless as much as possible. It is not like a citrus or queen palms where you have fewer things that are a challenge for it here. The more a plant is grown out of its native environment, the more time, emergy and expense is need to keep it healthy.

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