Xtremehorticulture

Fertilizing in the Fall?

Q. Is it too early to fertilize now my oleanders, lantana, rosemary, and chase tree? This could be temperature, nitrogen or iron. Try different fertilizers. If you find the right fertilizer it will become darker and greener. That’s how you know its a fertilizer problem. A. You can fertilize now (October) and skip the spring application. Woody plants put nitrogen fertilizer (whatever is “left over”) into “storage” until spring. The only plants you want to skip are the so-called “winter tender” plants which you don’t list (except the tops of lantana which are damaged at 32F). Those are the plants which are sensitive to winter cold damage and include most of our citrus and freeze tender plants like bougainvillea. You don’t want to stimulate new growth that could be damaged by freezing temperatures. This might include the more tender dwarf salmon colored flowered oleanders (5 foot and tender at 20F) but not the traditionally big ones like the reds and white flowered types (18 foot) which are cold hardy to about 10F.             Skip fall soil applications of iron fertilizers and wait to correct yellowing due to iron in early spring. Plants will respond to soil applied iron fertilizers best in the early spring. Fall applications of iron fertilizers are best when sprayed on the leaves. Use liquid detergent like dishwashing soap or (best) use a spray surfactant such as a wetting agent when you spray. Also it is best to use distilled water so the pH is not alkaline or acid. Better for iron uptake by the plant through its leaves. Makes more iron available.

Fertilizing in the Fall? Read More »

Cure Yellowing Eucalyptus Tree

Q. I have a 20 plus year old eucalyptus tree. The leaves are very yellow. What is the cause of this? Its not a simple answer when it comes to yellowing eucalyptus. Could be anything. Judging from the plants around it and recent water restrictions I am wondering if it is water related. A. Yellowing leaves can mean many things. It could be a nutritional problem, watering issues, or damage from insects or disease. I need more information as well as leaf and tree pictures. Make sure it gets an iron application to the soil in the spring. To be on the safe side, apply an iron chelate such as EDDHA. This is the iron chelate called iron EDDHA. Because of its chemistry it performs well in all soil pH if applied in the spring.             Check for a watering issue or a leak that floods the soil in that area. Eucalyptus is “mesic” in their water use so an application frequency for large trees should be used. When water is applied it should be deep and wide or large shrubs that receive water should be located under its canopy. Once a tree is chosen its increasing water use as it gets bigger has also been chosen.

Cure Yellowing Eucalyptus Tree Read More »

Apricot Poor Leaf Color Could be Fertilizer or…..

 Q. I have an apricot tree and the leaves are a lighter green during the past couple of months. Are the leaves lacking nutrients? Apricot leaves should be dark green when it is growing and in the summer. This color is a problem or late in the fall or winter just before leaf drop. Correct yellowing apricot leaves with an iron chelate applied in the spring or compost applied to the soil surface or both. A. Perhaps. Look at this year’s growth in several places as well as its leaf color. New growth should average about 18 inches for productive trees. Leaf color should be dark green. If leaf color is a light green and new growth is well under 18 inches, then consider applying a fertilizer or rich compost. Not all new growth of apricot is red. Some stays green. This is excessive new growth on a mature apricot and should be cut back. Prune it back with a hand pruner anytime you see it. You don’t have to wait until winter or leaf drop. Look at Growth and Leaf Color  Fruit tree fertilizer is applied in the early spring, usually once a year. Unless the soil is very, very, sandy, once a year application of a fruit tree fertilizer is usually often enough. Use the rate on the fertilizer bag as the maximum rate to apply. If applying twice a year, divide the rate on the bag in half. Apricots when young should get an average growth of 18 inches in a year. When it is mature maybe 8 to 12 inches of new growth each year. Apricot leaves showing inter veinal necrosis…or leaf yellowing. Defintely needs some iron chelate applied in early spring. But what about the leaf cupping? Weed killers can cause the leaves to cup. So can excessive heat in the summer. Soil Improvement Soil improvement may be needed also. Use rich compost instead of a fertilizer. Never apply a fertilizer or rich compost closer than 12 to 18 inches from the trunk. Both fertilizers and rich compost can damage plants if applied too close. To be on the safe side, water the soil immediately after the application of a fertilizer. Water “dilutes” fertilizer and rich compost. Never apply compost or fertilizer near the trunk or main stem of a plant. When applying a rich compost, rake rock or bark mulch away three feet from the trunk in all directions. Apply a thin layer (1/4 inch) of rich compost, water it in and rerake the surface mulch back into place. Do this once every year. If it is a nutrient issue from a lack of fertilizer, you will see a change in the leaf color in about two weeks. This color change will last months. Apricot tree near a lawn but the roots can choose where to grow. Growth might not be enough. Check fruit production last year, fertilizer applications and soil improvement. Inspect Irrigation Light green leaves can also be from either drought or watering daily. First correct daily irrigations during the summer. That’s a big no-no except for lawns, flower beds and areas for growing vegetables. Big trees and shrubs can’t handle that. When watering, apply water deeply to tall plants. If it calls for more continuous watering, increase the size of the irrigated area under the tree. Apply water to at least half the area under a plant. If the leaf color is light green, it may be a sign the tree is watered too often. Give the roots at least one day between irrigations during the summer otherwise the roots may “drown”. This gives the soil a chance to drain water and the roots to “breathe.”

Apricot Poor Leaf Color Could be Fertilizer or….. Read More »

What is Causing Citrus Leaves to Yellow?

Q. What is causing the leaves on my lemon tree to turn yellow?  This has been happening gradually all year. Readers lemon leaves A. Leaf yellowing of citrus is caused by any of these problems or in combination: high light intensity, micronutrient deficiency such as iron, irrigation and drainage problems and salinity. If the yellowing occurred during the winter and it was more of a bronze appearance then I would say it was due to winter cold. Looking at the picture you sent, some of the leaves have leaf tip burn. That could be caused by salinity or a lack of water. It is possible it could also be too much water or poor drainage but I don’t think this is the case unless you are watering it several times a week. Without more information I am guessing it is a combination of high light intensity, micronutrient deficiency and possibly salts. If the leaves were more “bronzy” looking I might also conclude it could be high light intensity if it is in a location with lots of reflected light. Yellowing of citrus leaves due to high light intensity Flush salts from the soil. Apply a large volume of water to the irrigated area under the tree to flush salts that might be causing a problem. Do this two or three times over a period of a few days then revert back to normal irrigations. Water no more than every ten days right now. Make sure the volume of water is sufficient to wet the soil 18 inches deep. When new growth resumes, resort to irrigating more often but this time of the year irrigating 10 days apart should be adequate. Unkinown nutrient deficiency of citrus but probably manganese or iron. Since iron deficiency is common in the Las Vegas Valley the KISS principle tells us to treat for iron If there is rock surrounding the tree, pull it a distance of 3 feet away from the trunk. If wood mulch surrounds the tree, you do not need to pull it back. Make sure wood mulch does not contact the trunk of young trees. Keep wood mulch 6 inches away from the trunk. Next, apply iron chelate containing EDDHA beneath the tree in January near a source of water. Cover the iron chelate with wood mulch to keep it out of the sun or make sure it is placed beneath the soil surface. Magnesium deficiency of citrus Next February or after fruit set apply a normal amount of fertilizer. Organic fertilizers are best. You should see a change in the color of the new leaves next spring during growth.

What is Causing Citrus Leaves to Yellow? Read More »

Bamboo Can Be Cut Back to Repair Winter Damage

Q. I have bamboo that was damaged last winter as you can see from my pictures. New growth is emerging from them but they are still yellow and brown. Should I fertilize them or give them iron? A. If the plant is still brown from winter damage and the growth is yellow, the only way to really make them look good again is to cut them down and let them regrow from the base. This kind of damage is never going to recover from unsightliness without some regrowth.             I assume this is a running bamboo like golden bamboo. They should come back if they are cut back to the ground but this is not the ideal time to do it. Prune cautiously this time of year.              It would be okay to cut back the largest ones now but leave younger ones until you saw some good solid growth again from the base. Once you see healthy growth, go ahead and cut more back. Otherwise wait until next spring which would be ideal.             Fertilizer and iron will be helpful as it is growing back.

Bamboo Can Be Cut Back to Repair Winter Damage Read More »

Bring Back Queen Palm from the Dead

Q. During the excessive hot spell in July our irrigation failed while we were out of town. As a result, one of our queen palms lost all its branches. In spite of subsequent life support, it does not appear to be coming back. Is that too much to hope for? Is there anything we can do to help it recover or should we just mourn its passing? Queen palms dead during first winter planted (1989/90) at local casino. Admittedly temperatures hit a 50 year low. A. Queen palms can handle heat but they struggle with extreme cold (25F) and hot, dry winds. In short, among the approximately ten palms we can grow here, they are not among the “chosen ones”. However, if these plants are water stressed or planted under poor soil conditions then they will not tolerate heat very well either.  Queen palm fronds from central bud yellowing during new growth             The only places here where I have seen decent, older queen palms has been in areas protected from wind, the soil prepared adequately with amendments and the use of organic surface mulches.  Queen palm with yellowing foliage after planting in rock mulch. Probably iron chlorosis and poor soil enrichment at planting.             Once they are stressed and water is withheld, they will suffer greatly. They need adequate soil preparation at the time of planting, good drainage, protection from winds and low temperatures, an annual fertilization program and organic surface mulches.

Bring Back Queen Palm from the Dead Read More »

Yellowing in Palms Can Be Lots of Different Things

This is California fan palm with cold damage from temperatures in the low 20’s or high teens F Q. We have a fan palm where the palms are turning yellow and I’m assuming dying. One or two would be acceptable but we are have 5 and 6 that are going bad. A. Let’s cover some ideas about why your palms could have yellow fronds. These are the main reasons: older fronds are dying from natural causes and should be removed; fronds were damaged during winter freezes; too much water applied too often or too little water; palms planted too deeply; palms planted in heavy soil that doesn’t drain well; palms planted with pure sand around the rootball; fertilizer problems such as iron, manganese or zinc. Not totally sure on this one but it was probably light cold damage on this date palm during the  winter in low 20’s Palms should be planted with the soil taken from the hole plus 50% compost and a starter fertilizer high in phosphorus added. Palms should NOT be planted with their root ball surrounded by pure sand in the planting hole which is commonly done in Las Vegas. The idea of doing that is absolutely crazy. Palms are high water users even though they tolerate high temperatures and our desert climate. Different types of palms require different amounts of water. The larger the palm, the more water it will require. Some of the highest water users will be date palm with their huge canopy spread. The amount of water will vary but most fan palms would be happy receiving about 20 gallons every time they are irrigated. This is Queen palm, not a good palm for the hot desert and probably lack of soil preparation or watering too often or both One of the common problems is irrigating palm trees with small amounts of water, like ten or fifteen minutes of drip irrigation, daily or even twice a day. Watering like this can fill the soil with water and suffocate the roots causing them to rot, diseased or both. So if you are irrigating your palms daily, don’t do that anymore! During the heat of the summer they can be irrigated two or three times a week, using 20 gallons each time you irrigate but the soil must freely drain the water away from the tree. In the wintertime you might be dropping your irrigation to 20 gallons every 10 days or perhaps even as long as two weeks. Sometimes the soil lacks certain types of minerals that palm trees need. Deficiencies like iron and manganese usually appears as a discoloration in the fronds at the center the canopy, the most recent growth. This can range from light green to nearly yellow. If these inner fronds are yellowing then we can usually narrow this to watering too often, poor drainage or a lack of minor elements such as iron. Center fronds, youngest, demonstrating yellow growth which could be due to watering issues, soil issues or possibly disease Next February when you make your annual application of fertilizer use a complete fertilizer such as a Miracle Gro, Rapid Gro, or Peters. You can also use fertilizer stakes. Make sure it is well balanced and try to select a fertilizer with the three numbers the same or close to the same value like a 16-16-16 or 10-10-10. Add an iron chelate that contains the EDDHA chelate in the ingredients. Let’s see if that works along with irrigating with a large volume of water but doing it less often. Cold damage on palms usually results in the older fronds turning a bronze color first and then browning later as they die. General rule of thumb is if more than half of the frond has turned brown, remove it. The new fronds at the center of the palm should be healthy and green when they emerge in mid-spring. If your soil is heavy and holds water a long time then plant on a mound 2 to 3 feet high and 6 to 8 feet across so the water drains away from the roots.

Yellowing in Palms Can Be Lots of Different Things Read More »