Xtremehorticulture

Xtremehorticulture of the Desert

Vitex Water Management Affects Blooms and Growth

14 Comments / drought, lack of water, no flowers, thin canopy, too much water, vitex /

Q. I have a Chaste tree that has been growing in my backyard for about seven years.  The branches have always been full of leaves and I would get an abundance of beautiful purple blooms. Last spring, I noticed there were not as many leaves and I would only get purple flowers here and there. This spring again the leaves are sparse and the branches are mostly bare. Should I be doing something extra to bring back the lushness of my Chaste tree? A. Vitex, or chaste tree, is relatively pest free. It originates from the Mediterranean region where the summers are usually hot and dry and the winters cool to cold and wet. Vitex in winter             The only real problems the plant has are if the roots remain too wet or the plant doesn’t get enough water. So my reaction to your question was concern about your irrigation practices; either watering it too often or not giving it enough water when you do irrigate.             Both could cause similar problems. If the roots stay too wet, root rots develop and you might see a thinning of the canopy and branches dying back. Watering too often results in poor growth or worse. If overwatering continues, you would probably see dieback in the tree and eventual death from root rots.             If the plant does not receive enough water, the plant canopy will begin to thin out and along with that a reduction in blooms.  If you feel like this tree does not get much water then try flooding the area around the tree once a week in conjunction with your irrigations. If the problem is not enough water, you should see a reaction to additional applied water in 3 to 4 weeks. Vitex in bloom             It also will do best with irrigations similar to other most of your landscape or fruit trees. This means regular deep irrigations.             Avoid daily irrigations. Water about twice a week during the hot summer months. In the spring and fall months, water deeply and thoroughly once in a week. As temperatures cool towards winter, you would probably irrigate deeply every 10 to 14 days.

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Redwood and Cedar Mulches Last Longer in Landscapes

Leave a Comment / cedar, mulch toxicity, redwood, stunt plants /

Q. Would you please tell me what type of mulch is not recommended to put in flower beds? I thought I remembered it being redwood mulch but I can’t find anything on that. Could it have been cedar?  My landscape guy says the shredded cedar is not a problem for vegetation. A. Actually either one will work just fine. Redwood and cedar mulches don’t decompose as quickly as pine and they are usually prettier.             Both cedar and redwood have phenols that help the wood resist decay by fungi and bacteria. There doesn’t seem to be a problem for bedding plants.             My preference is a variety of mixed woods but we do break down fairly quickly (two to three years) and must be replaced.             Many homeowners like the look of redwood and cedar mulches. They don’t break down as fast and so they last longer in the landscape. They may be more expensive initially but they don’t need to be replaced as often as pine mulches.

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Sappy Pine Trees Might Need Pruning Paint

1 Comment / bleeding, how to control sap from cut pine limbs, removing sap, sticky /

Q. I trim my 80 foot pine tree every 7 to 8 years. Each time I have buckets and buckets of sap coming from cut limbs. It just re-landscaped underneath this tree but I need to prune it again. I’m worried about all the sap that is going to fall on everything I just put down. Is there a way I might prevent the sap from dripping like using pruning paint? A. Most of what you hear is not to use pruning paints anymore to cover wounds on trees. They are considered primarily cosmetic and do not assist the tree in healing. That is true.             There are claims and some research to support the idea that pruning paints may actually cause some harm to a tree. But even so, they will not kill a tree or severely weaken it.             Pruning paints or similar compounds are still used in the propagation of trees such as grafting and topworking. The primary objection to using pruning paints is similar to why we no longer recommend using Band-Aids to cover a healing flesh wound.             In this particular case I would go ahead and try it since the benefit to you may get from using it may outweigh any negatives to the tree.

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Why Are The Leaves of My Locust Tree Turning Yellow?

Leave a Comment / black locust, borers leaf drop, Idaho locust, Robe locust, sunburn, yellowing leaves /

Q. Do you have idea why some many of the leaves on this Locust tree are turning yellow? A. The most frequent problem with locust trees, Idaho or black locust, is borers in the trunks. This will cause exactly what you’re talking about, yellowing of leaves and leaf drop, followed by branch dieback.             Borers entered the trees usually where it is sunburned and that is on the west and south facing sides of the trunk or limbs. Horizontal limbs may be damaged on the upper surfaces as well.             Check the bark on the trunk or limbs see if it is loose. It may easily pull away from the trunk particularly on the South and West sides. Large limbs may be damaged by sunburn. Sunburn on the trunk of a locust tree             Remove bark away from damage to areas and clean the damage down to fresh wood. You don’t need to paint it but if the customer wants it painted, paint it. Use a liquid insecticide soil drench to help protect the tree and give it a chance to recover.

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Independence Nectarine Fruit Damaged

1 Comment / nectarine fruit scarred, scarred fruit, thrips /

Q. I have a Independence Nectarine tree which I have been nurturing for two years now. This is the first year I have had fruit!  Of the nectarines I kept I am seeing something on them that looks like dried droplets of sap. It is not sticky to the touch but I have 2 nectarines that do not have it.  Are you able to determine if I have some sort of blight with the fruit? Will I just need to take this plant out? A. This type of sap, with all the scarring you see on the fruit as well, is caused by small puncture wounds to the skin of the fruit. When the skin is punctured on immature fruit, the sap oozes out of the hole and dries. Sometimes this dried sap looks like little squigglies coming from the skin.             The holes in the skin are caused by insects called thrips. These insects feed on the sap by pushing their long skinny mouth part, called a stylet, through the skin and rupturing it.             In wetter climates these punctures wounds can cause the fruit to rot due to infections. Here in our hot, dry climate the rotting doesn’t occur as often.             To keep your nectarine fruit tree from blemishes and scarring, you must apply protective sprays to the fruit early in the season. The most effective organic spray contains Spinosad. You don’t want to spray Spinosad or any chemical over and over again or you can end up with some problems.             You want to use two or three different sprays in rotation with Spinosad. Other organic sprays you could use in rotation with Spinosad include Neem oil, pyrethrum and insecticidal soap.             Remember that organic sprays do not last very long and may not cure a really bad problem that is underway. These chemicals are more effective when they are used to protect fruits when you see small numbers of pests.

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Warty Growths on Limbs Tree Solved

1 Comment / carob, disease, disorder, warts on limbs /

Recently some pictures were sent to me of some warty growths found on the limbs off crepe myrtle. But the tree did not look like crepe myrtle. And I did not recognize the warty growths. Read on to find out what was going on….. Q.I suspect this condition is related to a previous question about similar bumps on quince trees. I noticed these on my neighbor’s crape myrtle. You can see that the bumps cover not only the large, old trunk but are also all along the smaller branches. And these bumps are HARD! When you pick at them with a fingernail, they don’t budge. Crape myrtle is not usually susceptible to scale. But I don’t know what else it could be. A. This isn’t the same as the brown bumps on quince trees. Those were hard scale insects. These bumps are part of the wood itself. Crepe myrtle has some very characteristic leaves and flowers. This isn’t crepe myrtle. I have to admit that I was stumped. I sent some pictures to Andrea Meckley, the plant person, and she thought it looked like carob tree with a really big problem. Mature carob tree in Las Vegas with warty growth on limbs So I began doing some digging on carob. Carob grows well in the Las Vegas climate. We lost I think all of them in the Valley when we had a 50 year low temperature during the winter of 1989 to 1990. Temperatures in the North West part of the Valley dropped to about 2°F and even killed bermudagrass. We lost quite a few African sumac as well as the carob trees, many of our palm trees were damaged at hotels and around town. We lost a beautiful pine tree called Roxburghii pine. Remaining pines in the warmer parts of the city lost branches down to the trunk, but the trunk survived and to re-sprouted new growth. Those pines are still there across from Desert Springs Hospital on Maryland Parkway. If anyone is interested I will post some of those pictures of the survival of that pine. African sumac was replanted in town. Even though carob tree is a very good choice for our climate, it never regained any popularity. primarily because it is slow growing most likely. But it is relatively pest free just about everywhere in the world and a very interesting plant. Carob tree is a complicated tree sexually. Carob trees can exist as separate male and female trees or male and female flowers on the same tree. The scent from the male flowers is said to resemble the smell of semen so some might consider that offensive. It is grown commercially for the pods and seed which is ground and used as a substitute for cocoa. Unlike cocoa, carob does not contain the stimulant theobromine. There are different varieties of carob used for commercial production. As carob gets more mature it develops these warty growths near where the flowers are produced. This is normal. More on carob tree later. Thanks to Mindy for all the pictures!

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Japanese Blueberry Top Dieback Part II

Leave a Comment / japanese blueberry top dieback /

Q. The trunk/branches of the bad trees appear like they’re peeling. The limbs are very brittle so I don’t think they’ll recover. Could I, for example, simply cut the top 12” of the trunk and save the rest of the tree? Japanese blueberry with dead top I’m trying to understand why these specifically would get sunburned and not the others. Are you suggesting that if the top of the tree didn’t have enough leaves to provide shade to the trunk from the sun, this would occur? If that’s the case, even if I were to cut the dry part of the trunk off, I don’t know how I would keep it from occurring again…aside from attaching an umbrella to the tree!:-) I also attached a better photo of the trees directly adjacent to them (6 total trees, 4 are thriving/2 appear to be dying). These were all planted at the same time and it’s interesting that the two on the end (which are having problems) never grew as tall as the other 3. Dead top of the Japanese blueberry A. Yes, it appears to be sunburn. Just cut it off but this is exactly what can happen to a tree in a death spiral. It gets sunburn perhaps because the tree trunk was not shaded by enough canopy.  The sunburn causes the top to dieback which opens I more to sunburn. Borers come in and causes the tree to dieback more, sometimes killing it. You have no choice but to remove the dead part. Sometimes painting the exposed area of the tree with diluted white latex paint can help. It helps to lower the surface temperature of the limbs and reduces sunburn.  Sometimes just attaching some burlap loosely over the area and tying it in to it does not blow off can help until there is new growth that covers the area. Burlap added for some temporary shade Plants like Japanese blueberry, Podocarpus and others (often in the rose family or Prunus genus) gets sunburn due to very thin and tender bark. Hope that helps.

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Japanese Blueberry Tops are Dying Part I.

Leave a Comment / borers, dieback, disease, Las Vegas /

Q. I’m having a problem with my Japanese blueberries. Some are fine and the two on the end appear to be drying out but only towards the top? Do you have any idea what’s causing this? The soil is not dry and they all get the same amount of irrigation. Japanese blueberries tops dying back A. I would guess that something caused a problem on the trunk or large limbs at the bottom where it has turned brown. I am guessing it might be borers or some other critter that mechanically damaged the trunk/limbs. It is possible it could be sunburn as well particularly if they were open enough to allow direct sunlight on those branches/trunk for extended periods of time. I think we can rule out diseases in our climate except for the possibility of sunburn (non pathological disease). Look at the area of trunk/large limbs just in the foot above the healthy areas and let me know if you see peeling bark, discoloration or other types of abnormalities. If it is borers (the most likely), there is nothing you can do to raise it from the dead but you can protect it with a soil drench once a year using Feri-Lome’s soil drench. It contains an insecticide that should give you about one year of control from what I am hearing.

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Get Ready for the Leaffooted Plant Bug Invasion

2 Comments / almonds, flat legs, leaf legs, pistachios, pomegranate, red bugs, ugly bugs, weird legs /

Q. What is the best attack for these pesty, scarey looking creatures.  We had them last year.  Haven’t seen them yet this season.  Is there something to keep them away? A. This first part I am explaining will be a bit late for you now but prevention should start during the winter months when they can be seen in the landscape as overwintering adults ready to lay eggs in the spring. I have seen adults on bottlebrush in home landscapes in southern Nevada and I am sure they are probably overwintering on a number of evergreen plants in winter months. Since these insects can fly  as adults they will move from plant to plant for sources of food.  This means that they will come into your yard from neighbors as well all during the growing season. So just because you control them once during the season you will have them again as long as there is food in your yard for them to eat. What do we know about leaffooted plant bug? They like to feed on pomegranates, almonds, pistachios, tomatoes, peppers, cucumbers, squash, corn, peach, nectarine and I am sure some others. They are closely related to stinkbugs and squash bugs, feed and reproduce like them and can be confused with them because they look kind of similar. They overwinter from year to year in the landscapes. It takes about 50 or 60 days to produce adults from eggs laid in the spring. They feed with a long hypodermic needle-like mouth that is inserted into soft plant tissue like leaves and fruit. Their feeding early when fruit is developing can cause threads of sap to stick out of the fruit. Their feeding causes misshapen fruit or causes fruits or nuts to drop off of the tree. Their feeding can also cause diseases to enter the fruit. How to Control Them They are difficult to control because they hide unless they are swarming and reproducing near the fruit. Take Down pyrethrin based garden spray Hard or conventional pesticides such as Sevin or synthetic pyrethrins are the most effective for rapid kill. These can be found as ingredients in some common vegetable or fruit sprays in nurseries or garden centers. These same ingredients are used commercially where leaffooted plant bug is active. These types of chemicals leave behind a residual on plants that offer some protection for a number of days after they are applied. They also present some safety concerns for homeowners when used without caution in home landscapes so make sure you read the label thoroughly if you choose to go this route. Organic control is more difficult because these chemicals are short-lived and don’t leave behind much of a residual. You will not control this pest without more work on your part when using organic methods. That is the tradeoff when using organic methods. With conventional pesticides like Sevin a few passes during fruit set and development will give you some good control. Organic methods may require more inspection of the tree and fruit on your part and spraying more frequently. Soap sprays like Safers insecticidal soap will give good control if the spray lands on the insects. It leaves no residual once sprayed. Oils like Neem have been reported to give good control. Other oils include horticultural oils and canola oil. Organic sprays like Bt will not work on this insect. Spinosad has not been reported to work on this insect either. Another possibility is pyrethrin sprays which may give you good knockdown when sprayed on them directly.   A common mistake is to think that just because they organic sprays they will not hurt anything except the enemy insect. This is not true. Organic sprays will kill many different insects, good and bad. So directing the sprays at the enemy insects is important. It is also important to spray very early in the morning or near sundown. Spray when there is no wind and cover both the upper and lower sides of the leaves. Do not use one spray over and over. Use several sprays in rotation with each other so you do not end up with an explosion in the population of insects not controlled or building up insect immunity to the spray.

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