Fig with late spring freeze damage on the tips and leaves Q. I have a backyard orchard in Henderson with 14 fruit trees planted similar to what I have learned from the Dave Wilson videos and the UNR orchard. This is my 3rd year and I should be getting a decent amount of fruit. My problem is the figs. Two years in a row two fig trees have died to about 3-4 inches up the trunk. Last year I replaced both trees with new Kadota and Black Mission figs purchased from the nursery in pots. The new trees have apparently done the same thing. The trees are planted on the NE property line, so they get full afternoon sun. We had a very mild winter….I don’t really understand what is going on here. A. I am not sure what is going on either. If you are in a particularly cold part of the valley you could be getting some winter kill. It is not just the minimum temperature that matters. If low temperatures hit out of season (November or early December or mid February) they can’t handle the low temperatures they could normally handle in December and January. The important points in planting figs would be the same as the other fruit trees; add compost to the backfill at planting time, make sure it is planted the same depth as it was in the container, stake it the first year, it does not have to be whitewashed so don’t, keep the rabbits from it as they LIKE figs and will kill them, water them the same as other fruit trees, mulch them with wood mulch but keep the mulch away from the trunk 12 inches the first four seasons until established. Do not water directly next to the trunk but at least 12 inches away. Do not fertilize directly next to the trunk or you can kill them. They can be damaged by very cold winters, more so than apples or pears. I hope this helps.

Q. I would like to grow rhubarb here in Las Vegas. I live in Sun City Summerlin at about 3300ft. elevation. Any and all info would be appreciated such as variety, where to purchase, when to plant, shade or sun, in the ground or in pots, etc. A. We did try rhubarb at our orchard a couple of times with no success.  It could not handle the heat, primarily, which is my guess.  It is commonly believed that rhubarb will not grow in the Las Vegas valley and the purported reason among gardeners is that it needs some winter “chilling”. I am not convinced of this.             But my failure should not stop you because I did not give it a lot of my time and it was not planted in a protected area which it will require to “baby” it for the first couple of years until you learn how to manage it.             Rhubarb is probably not something I would recommend unless you are an experienced gardener and understand how to manipulate and manage your microclimates, soils and irrigation to get the response you need.              Your 3300 foot elevation will help a lot compared to our 2000 foot elevation at The Orchard. It would be very happy at 4500 feet or more. I would plant it in the ground.             Find a bright but cool location in your yard that will protect the plant from late afternoon sun.  Light shade will work just fine. I would usually suggest the north or east sides of a building. Winter cold is not a concern.             Pick a spot where it can be left undisturbed for the next 10 years.  This is a perennial crop, harvesting leaves and stems regularly through the growing season.             Dig the soil about 18 inches deep and amend with about 75% good compost. There is a lot of junk compost out there. In compost, you will usually get what you pay for.             Rhubarb can grow to four feet in height in the right climate. You will probably see it healthy during the spring and fall and really look quite bad during the hot summer months then rebound again in the fall. This is what we see with artichokes and other plants that are not supposed to grow here as well.             Plant the rhubarb rhizome with at least one good “eye” pointing up, three feet apart, about three inches deep. Fertilize with vegetable fertilizers. Mulch with straw to keep the soil cool and moist.             Place a basin around the plant to collect irrigation water and hand water until you see strong growth. Fertilize it in January to get started and lightly once a month when you are harvesting the leaves and petioles. The leaves are poisonous so just use the stalks or petioles.

Q. We have a question about our 5- 6 year old naval orange tree. For the past 2 to 3 years we left the fruit on the tree until the weather man said freezing temperatures were coming. But with just cold nights, the fruit seems to dry out. Can we pick the fruit early and let the oranges ripen in the house? A. Just a note. Navel oranges are real tricky here in southern Nevada. They have to be planted in just the right microclimate or they will freeze. I forwarded this question to my counterpart in Phoenix, Terry Mikel, for a response.             Navel Oranges tend to be a bit persnickety especially when they are young, no matter the cold, heat or whatever.  If you are seeing lots of leaves and small branch damage, then frost will be an issue.             Freezing nights will dry out any citrus fruits. The juice inside freezes and crystals rupture cell walls and the juice simply drains out. The problem with citrus, if the fruits aren’t ripe on the tree, they won’t ripen any more off the tree. Sorry.               There is another possibility and I am hoping that the ‘damage’ is due more to being juvenile and not as much due to freezing damage. If the leaves aren’t hurt by the freeze, then the fruits wouldn’t be either. As the plant gets more mature, there will be more “metabolism” going on and thus better fruits.

Some pomegranates have wonderful color inside like this ‘Wonderful’ pomegranate Q. I planted about 30 pomegranate bushes two years ago. I bought them from a nursery and they told me that I was getting a variety of exotic species. But they had them in the nursery so long the tags were all gone. They are all thriving now and most have a fair amount of fruit this year.  How do I determine when the fruit is ripe? Do they get easy to pick, like they nearly fall off the stem or is that even a factor? Do the seeds need to turn red? They are getting kind of leathery on the outside but most of those have seeds that really aren’t red at all. They are still a little tart but that may be expected. A few are smaller and really red outside and really quite red inside, but those are really bitter. So the real question I am asking is – how do I figure out when they are ripe? A. If we were all growing the same pomegranates it would be a lot easier. But not all pomegranates mature at the same time and they not all look the same when they do. Pomegranates can come in a wide range of colors             Some pomegranates are yellow on the outside, some red, some striped, some dark purple. Also the seeds on the inside are not always red or dark red. Some of the prettier ones are but no a variety like Utah Sweet (which I think you may).             They are a great variety but they do not look nor are they as pretty to look at as the Wonderful variety which is the most widely planted variety in the US. Some, like Utah Sweet, have seeds that are soft and nearly edible and in some cases people do eat them. Others, like Wonderful, have seeds which are hard. Some pomegranates may tend to split when they are ripe             Some have low tannin content and so are not bitter at all while some are quite bitter. Bitterness is an acquired taste and in some cultures is preferred. Think of the bitterness in beer or bitter melon. Some have a delicate balance between bitterness and sweetness that many people relate to the true taste of a pomegranate.             Some ripen by September while some ripen near Halloween.             Frequently the fruit will separate from the tree with a gentle tug and twist when ripe. It is true though that if you know which variety you have you can usually judge by its color and time of year.             Another way is the calyx end or the bottom where the “king’s crown” is. When it flares outward it is a good sign it is close to being ready.             Splitting of the fruit can be another indicator. If birds start to attack the fruit when they split that can be another indicator. Ground squirrels may also attack the fruit.             In any case they are ready when you think they taste good. Start looking at them around mid-September and pick a nice looking one and sample it. If it tastes good, then look for some at the same stage of maturity and harvest. Harvesting ripe off the tree can last a month because they are at different stages of development.             If not yet ripe, wait a couple of weeks and try another one. Keep going until you are satisfied you have the right timing. Mark it in your calendar. Take pictures of the mature fruit, send it to me and let me see if I can help you identify it.

Planting a Bareroot Fruit Tree Materials Needed: ·         Shovel ·         Predug hole three to four feet in diameter ·         Three to four cubic feet of compost per tree ·         Preplant fertilizer (triple super phosphate or high in phosphorus) ·         Wooden or metal stake at least four feet long ·         Hammer ·         Green nursery tape ·         Whitewash or white latex paint diluted equally with water ·         Paint brush ·         One 24 inch X 3’ section of one-inch hexagonal chicken fencing (if rabbits a problem) ·         Wood mulch ·         Bypass type hand pruner Planting hole for fruit trees with amended soil 1.    Dig hole 4 feet in diameter and the depth of the root system. It normally does not have to be dug any deeper than this. 2.    Reserve soil from the hole for mixing with compost called backfill 3.    Remove rocks larger than a golf ball. 4.    Add compost to the backfill and mix thoroughly. 5.    Add preplant fertilizer to the compost soil mix and thoroughly mix. 6.    Place tree in the planting hole and orient the bud union (dogleg) to the north. And make sure the roots will be ½ inch below the finished soil level when finished. 7.    Put three to four inches of amended soil into the bottom of the hole and start adding water. The water should turn the soil into a slurry (consistency of a milk shake) and flow around the roots, removing air pockets. 8.    Continue to add the soil/compost/fertilizer mix to the planting hole as water is added. 9.    When the backfill has been added completely, collapse the edges of the planting hole with your shovel to create an irrigation basin for watering. This basin should be level and have a depth of three to four inches. If a basin does not exist, create one by piling soil around the edge of the planting hole to create a moat. 10. Once the tree has been planted and the water has drained, check to make sure no roots are exposed. Draining may take anywhere from minutes in well drained soils to hours in poorly drained soils. If the roots are exposed, cover the roots with amended soil but be careful to leave a three to four inch deep, level basin (moat) surrounding the tree and encircling the planting hole. Fruit tree watered in but missing the stake to hold the roots from moving 11. Drive a four foot or longer stake with a hammer into the hole directly next to the tree. Make sure the stake is solidly driven into the soil at the bottom of the hole. The stake should be immobile after it is driven into the bottom of the hole. 12. Using green, pliable nursery tape, tie the tree tightly to the stake so that the tree is immobilized. When planting bareroot trees, the tree must be immobilized in its first few months during establishment in its new home. This allows for strong, healthy and fast root development by mid to late summer. The stake should be removed the following spring. 13. If the tree has not been whitewashed, then whitewash the tree using either whitewash compounds or diluted white latex paint (half water/half white latex paint). Paint the trunk, trunk bud union and any major stems coming from the trunk to a distance of two inches from the trunk. 14. Spread the wood mulch throughout the basin to a minimum of three inches. Pull the mulch away from the trunk of the tree six inches to allow for drying of the trunk between irrigations and avoid crown rot. 15. If you live near the desert, golf course or park protect your new investment with rabbit fencing.  Encircle the tee with 24 inch (wide) X 3 ft (long), one inch mesh, chicken wire. Tie the ends of the fencing together so that rabbits cannot get inside and damage the tree. Bury the bottom edge of the fencing two inches into the mulch. 16. If your tree does not have any limbs low to the ground, prune the main stem of the tree at knee height if you want your fruit production as low on the tree as possible. This will force the tree to produce branches and fruit lower to the ground for easier picking later in its life. 17. Irrigate the tree daily for the first three days to continue to remove air pockets. Wet the soil surrounding the hole and settle the plant into its new home.

Olives with mossy growth inside Q. I am a master gardener in Lake Havasu City, AZ. I am attaching photos of an olive tree at LH Baptist church. There are 4 trees and have been planted at least 40 years ago from what anyone can remember and they have “always” been trimmed into little balls. They are being watered for about 10 minutes every day in the summer and about 10 minutes twice a week in the winter. As you can see in the last picture, they do not have wells but have a raised brick planter box. It’s hard to tell but the tree is about 1 1/2 feet deep in this planter. Two of the trees are o.k. There are many basic problems with the care; however, my main question is that 2 trees appear to have some type of mossy growth inside on the branches. It shows up best on the last picture. Can you help identify this and give any advise for care. Olive mossy growth on the inside A. I am going to have to do some guessing on this one. This is not something that comes to mind easily. First of all telling me that they are watered in minutes doesn’t give me any idea of how much water they are getting. If  this is ten minutes on a traditional bubbler irrigation system then this could be between 10 and 20 gallons per day depending on whether these bubblers are one or two gallon per minute bubblers. If this is drip irrigation it could be anywhere from a liter of water to a couple gallons depending on the type of emitter, how many there are and how fast they release water. Let’s just assume I guess that they are not getting enough water. Olives are traditionally grown in Mediterranean climates; hot dry summers and cold wet winters. Olive trees are very drought tolerant but if they are being grown for their fruit then they must have adequate water during times of fruit production. Adequate water for trees is watering them deeply but infrequently. Deeply has to do with the quantity of water applied at the time of irrigation. Deeply means the water should be applied in a large enough quantity to water to a depth of about two feet deep in the soil surrounding the roots. If the water is not a good quality water, such as saline or water containing significant levels of salt, then it must be watered even more deeply to keep salts flushed from the roots. Olive flower racemes Infrequently means how often the water is applied. In your case, the trees are watered too often but MOST LIKELY not enough water is applied at each irrigation. So increase the volume of water applied  AND have the water come on less often. Now the mossy growth. This is where I am taking a bit of a shot in the dark. If these olives were planted 40 years ago they were olives that produced fruit. Fruitless olives were not being marketed then. There is no mention of fruit production. Olive flowers come out on clusters called racemes which also bear the fruit. If there is inadequate water (drought stress) the tree will have a rough time keeping these flowers and racemes alive and probably produce little to no fruit. My guess is that these are dried up flower clusters (racemes) that never were sustained for producing fruit either by a lack of pollination or enough water to keep the raceme alive and so the raceme dried up giving you the “mossy growth” you are referring to. But this is just an educated guess.

            Question. Where can you go and visit Egypt, Sherwood Forest, New York, a tropical island, a Pirate’s island, Monte Carlo, the Italian Riviera, jet skiing on a large lake or snow-skiing on a nearby, 14,000 foot mountain all in a day? Las Vegas now boasts the eighth busiest airport in the United States and the tenth in the world. When you count tourists and convention delegates at 32 million each year, their isn’t any city busier. The closest comparison would be the crowds visiting the Orlando area attractions, the busiest multi-city area in the US. So what’s the problem? It isn’t what you think. Yes, Las Vegas receives less than 4 inches of rain each year. Yes, the summertime temperatures soar above 110 for long periods of time in the summer. Yes, the humidity is usually below 10 percent and the wind speed is usually among the highest in the Southwest. But many places  in the desert Southwest are like that. Corrosion to sidewalk from salts             It is the soil. The soils in Las Vegas are among the worst of any major city in the world. Native desert soils have salt levels 25 times higher than most Extension Services would consider safe. Boron levels, where one ppm can be considered lethal for many plants, can exceed 40 ppm in isolated pockets designated for development. With pH levels often over 8.5, sodium  and caliche change the soils so much that they require picks or jack hammers for planting. Las Vegas soils are frequently very high in gypsum. The gypsum levels are so high that there are two gypsum wall board plants in the area. The sulfates contained in gypsum can be extremely damaging to unprotected steel and concrete. Water has been cheap in Las Vegas in the past. This, combined with the efforts to promote tourism and gaming here, has created an artificial, desert rainforest in the urban areas. The highly soluble gypsum has dissolved in these irrigated desert soils, leaving voids that are filled by collapsing soils that damage walls, foundations, roads and structures. The Colorado River water used for irrigating in Las Vegas contains one ton of salts per acre foot. What does that mean to residents? A normal lawn irrigated in Las Vegas will receive about 600 pounds of salt each year. Salt damage to block walls due to salt in soil and water             Even with its problems, the gardening season in Las Vegas extends through most of the year. The heaviest planting season is in the spring but fall planting is a regular and growing practice with Las Vegas residents. Most major nurseries like the string of Star and Plant World nurseries operate throughout the year with some seasonal sales during the slow months at Christmas. There are essentially no wholesale growers in southern Nevada. In fact, there has never been an attempt at wholesale growing since the population and growth spurt after 1984. Currently, Las Vegas is a retail market in nursery goods with wholesalers from the surrounding states. Major plant sales are through direct sales or plant brokers. The use of color in business complexes, hotels and wholesaling to mass merchandisers like Wal-Mart, Kmart, Target, Home Depot and Builder’s Square and nurseries is big in Las Vegas with the dollars all going out-of-state. Yet publications and syndicated talk shows claim that Nevada is the number one state in which to establish a new business. Las Vegas Valley Water District Desert Landscape Award Winner             Las Vegas is a service-oriented town. The 4 – 6,000 people who moved to the area each month until a few years ago come here with the expectations of a 24 hour town and having a good time. Many want the freedom that service companies provide to avoid the heat and have the time to enjoy a 24 hour town. Rough estimates of the percentage of residents using lawn maintenance companies would put it at about 10 percent. The traditional grass/tree/shrub landscapes are becoming a thing of the past because of increasing water costs and environmental awareness. Because of a heightened awareness in conserving water and sensitivity to the desert environment, there has been a growing trend toward a dry-type of landscaping. Desert-adapted plants and examples of the Sonoran desert landscape “feel” have been becoming more attractive to new residents. This has presented installation and maintenance problems to old time landscapers who “grew up” with the old Las Vegas mentality of “keep it green” and “green side up”.             The megaresort gardeners are faced with a huge problem the moment a landscape architect from outside the area draws up plans for a new hotel.  Under the demands of the owners, the new property must be different than anything else already here and give an appearance that the customer is not in a desert. Seventy-two and 90 inch boxed trees like English oak are brought in from the east coast on flat beds in the middle of summer to a meet a deadline for “Sherwood Forest”. Pine needles are brought in by the boxcar load on a train to simulate a Carolina landscape. Eighty acres of sod are trucked in from out of state on a revolving caravan of flatbeds to meet a deadline for a recreation facility. A few years ago the whole idea would have been preposterous. Now it’s being done. TPC one of the desert southwest courses             Horticulture in Las Vegas is big business. And like the craps tables, it can be in one big throw. Approximately 5 percent of a hotel’s construction and material costs are in landscaping. This doesn’t take a genius to figure out that a billion dollar megaresort owns a good-sized nursery when it’s completed.  A few years ago the gardening done in the hotels were done by a small union crew out of the Engineering department. The whole operation would be overseen by the Director of Operations. Because of the high degree of technology now involved in gardening at

            One of the fears about landscapes designed for desert environments is that the design will actually use more water than was anticipated. In the process of using more water than anticipated and lack of attention to design considerations, the energy consumption of the building or home might increase. Minioasis concept taken from Sunset Magazine many years ago. Hope you guys don’t mind.             Landscape designs are extensions of the home and should provide usable areas that add to our quality of life. Recently a homeowner asked how to know if a landscape designer was a good one or not. A good designer will sit down and ask you what your needs are as a family or a business. A good designer will incorporate as many of these needs as possible into the design.. If the designer doesn’t ask about your needs, get a different designer.             Concentrate most the plants near the home and decrease plant density away from the home or building. Common terms used to describe this are minioasis and hydrozoning designs. This technique allows you to use high water use plants near the foundation where shading of the windows and walls can occur. In Las Vegas, where we have some gypsiferous soils in parts of the valley, this can present a problem if these “foundation plants” are overwatered. The high sulfates contained in some of our soils may damage concrete patios and foundations. Check with a soil survey map or have the soil analyzed for high sulfates. The only solution to this type of problem is to keep foundation plantings on drip emitters and far enough from concrete so that the water/soil solution can’t react with the concrete. Most cement companies use appropriate, resistant cement in their batches.             Shade south and west facing walls. Some research in the past few years has indicated that shading the south and west facing walls, not the roofs, helps to reduce energy consumption of buildings situated in desert landscapes. This can be accomplished with trellised vines, shrubs or well-placed trees. Using large trees in desert landscapes to shade is questionable due to water use             Use trees that are in scale with the building. Large trees use more water than smaller trees. Even if a large tree is a so-called low water use tree, a smaller tree that might not be as water efficient may save water in a mature landscape. Water use rises dramatically with tree canopy volume. It makes no sense at all to plant a 40 foot tree to shade a one story building in our desert environment. Our main problem is to find good, small trees for small residential landscapes. More attention needs to be paid by our nurseries to developing some of our reliable large shrubs as small, specimen trees. Ikebana floral designs use spaces creatively             Use open spaces creatively. You’ll never save water by covering the soil with a plant canopy. The desert doesn’t do it and neither should we. Instead it is the challenge of a good designer to find creative ways to use open space. In Las Vegas of the past, if the designer had bare ground, they covered it with turfgrass. That time is gone and most people now realize that 100 percent turfgrass cover is irresponsible in our desert climate. Use turfgrass as a functional landscape planting, not a groundcover. It may be used to surround trees and shrubs that don’t do well under drip irrigation.             The temptation might be to replace turfgrass with a green, desert groundcover like myoporum. That would be a mistake. Recent research in Las Vegas has demonstrated that myoporum uses over thirty percent more water than high maintenance bermudagrass. Play it safe. Be creative. Open spaces don’t use water.             Consider hardscapes (boulders, covered patios, artwork, bridges, masonry, gazebos, fences, archways, benches) as alternatives to unnecessary plants in the design. Hardscapes don’t use water. Can a piece of hardscape be used to create shade instead of a large tree? Can it act as a focal point? Save plants for important items in a landscape and make them count. Plant use should be questioned if they are acting as a landscape filler.             Incorporate elevation changes in the design to create interest, create areas in the landscape to collect water and protect sensitive plants. Elevation changes provide niches for plants that might not survive normally.             When landscaping or relandscaping, a conscious effort should be made to follow the lead that deserts provide for us. Observe their characteristics and mimic them in the landscape. The house or building is situated in a “minioasis” in the desert landscape where it is protected from the harsh elements. Here it offers a retreat providing recreation, safety and comfort for the desert dweller. Checklist: What Should I Consider in a Design That Will Add to the Quality of Life in a Desert? How can I channel available breezes into living areas What are my solar angles and where is the sun shining from during the summer How can I control prevailing winds that are a nuisance Will there be glare into windows from my design Can I do anything to reduce dust problems inside the home Where do I need focal points and splashes of color How can I create interest with bare ground or “negative space” What kind of microclimates am I creating with my design What kind of spaces am I defining with my design and are they functional Am I creating areas of recreation and areas for leisure activities Am I creating shady spots for play areas, parking, patio, deck Am I shading the windows Am I considering attracting wildlife through the design Am I avoiding allergy plants Am I creating a safe design sensitive to the family’s needs and concerns Am I addressing their privacy concerns Am I stimulating all the human senses, not just sight

Quince fruit tree at The Orchard Q. My family has for many years had access to wild abandoned Quince bushes “trees”. They apparently were part of an old homestead in our native Orinda, east S.F. bay area. We have since moved from there, and see that you list this fruit as a tree that may survive here in the Vegas area with the proper soil. We have not been able to find the fruit available anywhere, it seems to be one of the forgotten. Apparently it is popular in the mediterranian to some degree. Any help finding a source to pick or buy would be greatly appreciated. There are seeds available though, and growing our own is looking like our only option. My mother lives here in Vegas, I am her son and now reside in Humboldt county “Willow Creek”. Quince fruit A. I have brought quince into the valley from Dave Wilson nursery and they are hard to sell. Not many people know about them and even fewer know what to do with them. I see that Bay Laurel nursery, an online nursery, carries quince; all three commonly recommended, orange, pineapple and Smyrna. Any will grow here in las vegas with few problems except iron cholorsis (leaf yellowing with green veins you use chelated iron in the soil in January EDDHA type or 138 Fe) and borer problems so whitewash them. Quince is popular in Mediterranean and some Arabic/Persian cultures where it is used in cooking a lot. Makes some great candies, infuses wonderful aromas into foods and makes great jams, jellies and compotes. Yes, improve the soil at planting time with composted manure and use organic surface mulch as I recommend and it performs well here with high quality fruit. http://www.baylaurelnursery.com/quince.html

Q. I have 4 oleander bushes that were doing great, now 2 of them are drying up the leaves are turning light and they are crunching up, what is going on. The ground seems wet enough, what is happening. I need your help are the dying? Freeze damage and spring recovery oleander A. The information I think I have from you is that you have four oleander bushes that have done well for several years and now some of them are drying up after a previous several year history of doing very well. The number one problem is a lack of water. I usually try to focus on the easiest possible reasons first because they are the most common. I realize your reaction will be to say it is not that but please check to make sure the water source has not been blocked, if this is drip irrigation, or reduced dramatically. I would assume that they are on the same valve so they are getting water at the same time off of the same irrigation valve. Also please realize that if the water was turned off for a long time, and then turned on again, that the soil can be moist but moistened after the damage was done. Not oleander but pittosporum with drought stress There is a lag time between damage to the plant where you will see the damage (leaves are dry and crunchy) and when the damage occurred. This could be a week or more. Visual appearance of drought damage lags behind the actual time the damage occurs. If it was drought damage, they will recover if water is reapplied and it is done before too long of a time (if the water is turned off for months when it is hot the plants will most likely not recover). The type of oleander may also dictate damage like this. For instance the petite oleanders, with the salmon colored flowers, are damaged with light freezes. The standard oleanders (large shrubs whites, reds, purples, etc.) are more cold hardly. However, there are differences in cold hardiness (dieback to or near the ground) between even the standard varieties but many of these die back ranging in temperatures dropping below 20F and down to about 10F. A few diseases but not much. There is one oleander disease that has, to my knowledge, been found in southern Nevada that causes leaves to scorch… appropriately called oleander leaf scorch disease. It has been found in southern California and Arizona. Here is a link to some information on the disease but it usually does not cause the entire plant to die since you can cut it to the ground and it will regrow with uninfected plant parts. http://ag.arizona.edu/plp/plpext/diseases/trees/oleander/oleleaf.htm Other rare disease problems include sooty canker and root rots but this would be highly unlikely from your descriptions AND they typically do not cause total plant death. Because oleander has so few problems in our climate we start getting into some weird and highly unlikely possibilities which center mostly on the soil and what may or may not have been put on the soil close to the plant. So then you have to go back into the history of how the plants were managed. Was there anything applied to the soil near them? Fertilizer applied right next to plants can cause scorching and even plant death. If it persists, replace the plants and the soil in those spots if the irrigation checks out okay.