Xtremehorticulture

Xtremehorticulture of the Desert

Dormant Sprays or Dormant Oil?

Leave a Comment / Copper fungicides, dormant oil, dormant spray, spraying fruit trees in the spring /

Q. I have a peach tree that has been in the ground one year. I was supposed to spray it with dormant oil spray before leafing out. Is copper fungicide okay for spraying in the spring? Want to avoid bad pesticides because of birds, good bugs, etc.  A. There is a confusion out there concerning dormant sprays and dormant oil. Dormant sprays can be a number of different types of sprays. The name “Dormant Spray” is a trade name and tells me nothing about its contents. Dormant oils or horticultural oils help prevent insect pests in the coming growing season If I have the trade name (Dormant Spray) and the manufacturer then I can look it up and I will know exactly what it contains. There is no hard and fast rule that you can apply when you are talking about dormant sprays. However, dormant sprays are usually a traditional pesticide or combination of traditional pesticides that are sprayed during the winter or early spring. Sometimes they contain a fungicide that has copper in it and sometimes they contain an insecticide as well. They are not typically organic. Dormant oils, on the other hand, are very specific. They vary a little bit among manufacturers but not like dormant sprays. There is no reason for spraying a copper fungicide contained in the dormant spray if there are no problems to solve. However, dormant oils are very important to apply as a preventive measure for controlling some of the insects common on fruit trees. There is no reason for spraying copper fungicide now unless you have a good reason for it. Be sure you have a SPECIFIC reason for doing this before you do it. On a one year old peach tree I doubt it unless you have disease pressure from Coryneum blight/shothole fungus.  If we have extended periods of wet weather or rain you might consider it after the rain has finished. But otherwise I would not do it.

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Small Area Will Fit Trellised Fruit Trees

1 Comment / espalier, fruit trees, small spaces, Trellis /

Q. I have a very small back yard and a 20′ x 18″ planter against the back wall of our property that is now empty. We were thinking of espalier fruit trees in the space. My wife wants a Myers lemon and I like a peach or nectarine, pear, or even an apple. A. You can fit about three fruit trees on a trellis 20 feet long. They don’t have to be dwarf except for the apple. The easiest trees to trellis are those which produce fruit on spurs; most apples, pear, apricot, plum and pluot. Citrus will work if the location is in a warm microclimate during the winter and protected from the wind. Apple trellis to close to a century fence but not on the fence Nectarine can be difficult because it frequently requires a lot of spraying for Western flower thrips to prevent the scarring this insect causes to the fruit. Peach can be more difficult because it does not produce fruit in spurs. Purchase these trees at any local nursery or garden center but reference my list for the best varieties. You will find it on my blog or email me and I will send you a copy. Buy a small tree if you are going to trellis. The wires for trellising should not be against the wall but away from it at least a few inches so you can prune behind it. Trellis wires start at a height of about 18 inches from the ground and vertically spaced 18 inches apart. Everything growing towards the wall is pruned off. In the first year cut the top of the tree about 2 inches above the bottom wire. The growth closest to the cut is directed to the next wire above it. Two side branches are tied tightly to the bottom wire. Next year repeat this process at the second wire, then the third wire and finally the last wire. Once the tree occupies the entire trellis any branches growing above the top wire are removed. Branches growing away from the wall are cut back to three or 4 inches.

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Cut Oleanders down Now

Leave a Comment / How to prune oleander /

Q. You had an article awhile back about trimming oleander down before spring. I have five in my backyard and have never done that. I am afraid to trim them down. Let me know because I am ready to fertilize. A. If oleanders are getting old and unsightly you have two choices if you want to improve their locks. You can cut them down to the ground leaving stubs about 3 to 4 inches above the soil and they will sucker and regrow from these stubs. This eliminates flowers early in the season but it will start flowering probably around July when it gets old enough. You can cut them back now. They grow back very quickly when it’s warm and they have plenty of water. The second option cuts back a few of the oldest and largest stems in the same way but leaves the smaller ones unpruned or only cut back with some of the foliage remaining. The advantage of the second way is that you don’t leave and open space and the remaining smaller stems will flower much earlier. Pruning them with a hedge shears in the spring and summer removes the future flowers and you’re faced with a green plant until it regrows and flowers. Fertilize them and water them after they are pruned. This is important if you want them to grow back quickly. Here are some places on my blog to check out  http://xtremehorticulture.blogspot.com/2012/07/proper-way-to-prune-and-hedge-oleanders.html   http://xtremehorticulture.blogspot.com/2014/08/best-time-for-pruning-oleander.html http://xtremehorticulture.blogspot.com/2015/12/when-and-how-to-prune-lantana-and.html

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Pine Tree Dripping Sap from Holes

Leave a Comment / borers, sapsucker, woodpecker /

Q. I have a one-acre lot in east Las Vegas with large pine trees. One of the trees recently started dripping lots and lots of sap. Upon inspection, we found some horizontal lines of holes in the bark.  Other areas the sap is just dripping from the natural seams of the bark.  I looked online and it suggests a bird rather than a borer if the holes are in lines. Are there woodpeckers in Las Vegas? A. Yes, we have the yellow-bellied sapsucker here which is in the family of woodpeckers. They cause the kind of damage you are seeing and drill holes in horizontal lines which can drip sap. It looks a little bit like someone took a drill and drilled holes in the tree close together and in a straight line. There is not much you can do except to try to exclude these birds from the trunk which is difficult. The good news is that these trees can live many years with this type of damage from this bird if the tree is healthy and growing. Big pine trees use a lot of water so make sure yours is receiving enough water in the spring and summer months so that it will grow enough and recover from the damage. If damaged trees do not grow enough to recover from the bird damage then it can be a problem for the tree.  Try looking here on my blog http://xtremehorticulture.blogspot.com/2011/08/someones-drilling-holes-in-my-trees.html http://xtremehorticulture.blogspot.com/2014/04/holes-in-trees-due-to-woodpecker.html http://xtremehorticulture.blogspot.com/2015/01/what-caused-holes-in-my-tree.html http://xtremehorticulture.blogspot.com/2015/01/time-of-year-for-holes-to-appear-in.html

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Lemon Tree Leaves Eaten up

Leave a Comment / citrus leaves eaten, Lemon tree leaves /

Q. I have a lemon tree with the leaves eaten up by something. I have been spraying with soap and water weekly but I’ve not seen any improvement. Any ideas? A. I looked at the picture of the leaves you sent. Damage caused by critters is frequently characteristic to the feeder. The leaves are chewed from the tips and entire portions of the leaf are gone. Commonly we see root damage but this does not look like root weevil damage. Root weevil damage leaves a characteristic “notching” along the edge of the leaf. Rabbits can damage citrus but they usually eat the small twigs or branches and entire leaves. This damage usually extends only as high as they can reach. For cottontails it is about a foot. For jackrabbits it can be 2 ½ feet or more. Rabbits also damage the trunks if the trees are fairly young. It does not look like rabbit damage but I will not rule out rabbits. Look at where the damage is located on the tree and see if it extends to a certain height only which might point at rabbits. This damage resembles grasshopper damage to the leaves but I would not expect damage from grasshoppers this time of year because they are not active now. Perhaps this damage happened awhile back and you are just now seeing it. Soap and water sprays will not leave behind a toxic residue that kill pests. Soap and water sprays will only kill insects that you spray. Traditional pesticides like Sevin insecticide will leave behind a toxic residue. Try spraying with Sevin if the lemon tree is not in flower. The damage resembles the chewing from insects such as grasshoppers and Sevin insecticide should do the trick. Citrus leaves eaten diagnosis from University of California

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Don’t Confuse Leaf Drop with Ash Decline

Leave a Comment / ash decline, ash tree branches dying, ash tree dying /

Q. I have an ash tree which appears to be dying. I am considering taking it out but would like to have someone look at it before I do. A. The usual problem here with ash trees has been a disease called ash decline or ash dieback. I have posted questions I received regarding this problem on ash trees along with pictures of what it looks like and what to do if you have it. Ash decline             Send some pictures to me of the tree showing the problem when you see the problem. I need close-ups of the leaves as well as a picture of the entire tree. Look at the pictures I have posted here or on my blog to confirm it. This disease is quite easy to identify from pictures.             If you are certain the tree has this disease it should be removed. There is no cure for it. This email was confirmed as ash decline and the tree removed.

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Greenhouse Space Heaters Need Air Mixing

Leave a Comment / growing from seed, How to grow transplants under lights, lights to use when growing transplants, tomato transplants from seed /

Q. I have a small greenhouse I would like to heat at night to prevent the freezing of some seedlings. I am guessing I will only need heat for the month of February. I was thinking of a small space heater. A. It is much easier and more effective to provide bottom heat to warm seedlings than a space heater that only warms the air. Provide bottom heat by using waterproof heating mats beneath the seedling containers or trays. They are available locally from nurseries and garden centers.             Many vegetables that grow during the summer months require warm soils for good germination. Seeds like tomatoes and peppers will fail or germinate very slowly if the soil is not warm. Years ago we would place seedling trays on top of the television or refrigerator where it is warm enough to complete or speed germination. As soon as they germinated, they would be placed in some light or directly under very bright lights. Drape plastic or a light blanket over the seedlings and heating mat at night and remove it during the day. Seedlings require 6 to 8 hours of full sunlight, or the same intensity from electrical lights, as soon as they germinate. Sunlight intensities or durations shorter than this will produce spindly transplants that will grow and transplant poorly. You don’t need expensive grow lights for growing transplants. Fluorescent lights or LEDs are fine but they must be placed within an inch of the leaves to produce enough intensity to support good plant growth. Be very careful when using incandescent bulbs, or lightbulbs, for growing seedlings. They produce a lot of heat and damage plants at distances close enough to produce enough light intensity. I leave electrical lights on about 16 hours each day when growing transplants.

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Plum Sap Not Always Disease or Insects

1 Comment / Borers in plum, disease in plum, Plum sap /

Q. My plum tree has sap coming from it in bubbles. Does it have some sort of disease? A. Sap coming from a tree is a response by the tree to some sort of damage. Damage that causes sap to ooze in bubbles from the trunk or limbs can be caused by the environment, disease or insects. Plums are normally very sappy. When plums are pruned during the growing season they respond to fresh wounds by releasing a large amount of sap. Trees that produce sap in response to damage or an attack is their method of protecting themselves. Sap losing from cut limb on plum When insects that burrow into the tree and attack it, such as borers, the release of sap can engulf these burrowing insects and suffocate them. If the burrowing insect is still active, chewing and feeding away when sap is released, these bubbles of sap will be dark in color but cloudy. The sap is cloudy because it is full of sawdust or wood chips from the feeding by these chewing insects. If the tree successfully engulfs and kills this destructive critter, the sap continues to be dark but free of sawdust or wood chips and therefore clear. Sap also helps flush disease organisms from wounds. The presence of sap from plums and apricots does not always mean there are disease or insect problems. Sometimes environmental damage to the tree can cause sappiness. Environmental damage can occur from intense sunlight, heat and water stress. Take a sharp knife and remove the bubbles of sap all the way to the surface layer of the tree. Remove the surface layer of the tree so that you can see what’s going on just under the bark. Look at the exposed area under the bark and inspect it for insect damage. You may find the insect itself. Regardless, it is a good idea to remove the sap bubble and inspect the exposed limb or trunk just under the bubble. If an insect or its damage is present, clean out the damaged area so that everything looks healthy and the tree can heal on its own. There is no reason to apply anything to this wound afterwards if the knife was sanitized first. Use alcohol to sanitize the knife, heat from a lighter or household sanitizer such as Pine-Sol. Be careful with bleach, (even though it is a good sanitizer) because it rusts tools and destroys clothing.

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No Fear of Disease after Spraying Liquid Fertilizers

1 Comment / bacterial leaf spot, leaf disease, Micronutrient sprays /

Q. Can foliar spraying micronutrients like iron on fruit trees cause bacterial leaf spot to form or spread? I have had problems with bacterial leaf spot on my nectarine trees but last year the leaves weren’t affected as much. I don’t want the pathogen to spread again. A. Where do you live? Who made this diagnosis? I have not heard of bacterial leaf spot forming in the dry desert. In more humid climates it can be more common. The leaf spots on leaves should be surrounded by a yellow halo if it is bacterial leaf spot. Some iron sprays can cause staining on developing fruit and can resemble disease. This is iron staining quince fruit. Use iron chelate sprays if fruit is present. Bacterial infections usually require wet or humid environments and warm to hot temperatures or insects to spread the disease. And these wet/humid environments must be present over a long enough period of time usually many consecutive hours. It would be possible if the plants are crowded together so that the leaves cannot dry or there is an air movement to help dry them. Overhead irrigation such as sprinklers could also contribute to a problem. However, applying foliar micronutrients early in the morning so the leaves have a chance of drying before nightfall there should not be a problem. And spray early in the season. Some diseases like shot hole fungus are prevented with properly timed fungicide applications containing copper. Copper fungicides can also be used to help prevent some bacterial infections like bacterial Leaf spot. The pathogen or bacteria are already present on stems and move to the foliage early in the spring. The leaves just need the right environment (temperature and humidity or degree of wetness) to cause infection. It also helps if the canopy is not dense so there is air movement to help dry the leaves. In your pruning you should create enough space between branches to allow for some sunlight to penetrate inside the canopy and reduce shading. You probably have been told that there are not many pest control products for bacterial diseases but a fairly common fungicide like Bordeaux can give you some good protection if applied when temperatures get warm. Some of the disease potential can be removed through pruning in the winter.

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