Q: I have a Calamondin citrus tree in my yard and I have no idea what to do with the fruit since it is too sour to eat.
A: Calamondin, Citrus mitis, is an acid citrus fruit originating in China and introduced to the U.S. in the early 1900s. It can be eaten but the fruit is quite tart. So, what can you do with the fruit? The whole fruit has been commonly used in cooking with chicken, seafood and fish. The juice has been used as flavoring in beverages, baked goods, sauces, marmalade, and soups. Calamondin is generally used as an ornamental citrus with some landscapers selecting it to replace typical hedges. It is incredibly cold-hardy, able to survive in temperatures as low as 20ºF beating out other cold-hardy citrus such as kumquat and satsuma tangerine, The fruit is small, generally only about 1 – 1.5 inches in diameter. It should be used within a week of harvesting as the fruit does not store well. Calamondins make a very good patio tree and can be easily grown in a large container. It is best to place citrus is a very sunny area although it can produce fruit well with some late afternoon shade. Irrigating too much or too little can be a problem for fruit production but generally it is better to err on the side of less rather than more water. Fertilize using a slow-release citrus fertilizer in March, June and September. You can use 6-6-6 or 8-8-8 fertilizer for fruit trees once every six weeks starting in March through September. Pruning is only required to keep the tree the size you desire.
Q: What is this white powdery stuff on the trunk of my citrus tree?
A: This pest is called citrus snow scale and believe it or not - it is an insect. Citrus snow scale attaches to the trunk and sometimes when populations are extremely high, it can be found on leaves and other parts of the citrus tree. The insect feeds on the plant juices diminishing the nutrients available to the tree. The insect reproduces in large numbers to cover the trunk tissue where it resembles “snow.” Armored scales are distinguishable from soft scales by the removable cover or ‘armor’. As crawlers, the females of snow scale insert their long mouthparts into suitable hosts and never move again. The immature males become immobile once they begin feeding and remain immobile until they emerge as winged adults. In severe infestations, the bark of the trunk or limb can split, making the tree vulnerable to fungal disease. Citrus snow scale has a tendency to pile up on top of one another making chemical application difficult to reach the bottom layer. Consider brushing the stems and branches with a soft toothbrush or larger soft brush first to remove some of the layers of the scale. Then apply insecticidal soap or all season horticulture oil. More than one application will be required.
Q: My citrus tree is dying and I think I have citrus greening.
A: I have had this question 4-5 times within the last few weeks. First, we do several confirmed cases of Huanglongbing (HLB) here in Nassau County Florida. The correct name for "citrus greening" is Huanglongbing (HLB). Secondly, there is no cure or chemical spray to prevent the disease at this point. In addition, some of the nutrient deficiencies and root decays can mimic several of the symptoms of the disease. Just because your fruit is not totally orange or yellow, does not necessarily mean you have HLB. We should be diligent about controlling the insect which we believe transmits the bacterium. I have found it on the citrus at my Yulee office even in January although it is most active in the spring and summer. I would suggest using insecticidal soap or horticulture oil for controlling the insect and the chemical must come in direct contact with the insect to kill it. Neither one of the chemicals listed above have any real residual effect so it is a waste of time, money and chemical to spray the tree if the insect is not present. This means you must see the insect and use the chemical directly on the insect for it to work properly. Do not use heavy broad spectrum insecticides when the other two work beautifully. Severe cold temperatures in the winter and harsh, hot temperatures in the summer can weaken the bacterium internally once it is inside the tree. We are hoping this may slow the spread of the disease and provide a few more years of productivity but there are no guarantees. More importantly, how can we predict or be sure either of these environmental conditions will occur? The best diagnosis for HLB is the asymmetrical, blotchy yellowing of leaves. Think about folding the leaf in half, right down the middle (lengthwise). If both sides of the leave look somewhat the same, then your tree does not have HLB. Look over the University of Florida document which will provide the best and most accurate information on identification. This disease has devastated most of the citrus industry throughout the world. We will just have to ride this out and hope for the best as backyard growers – it is definitely a deadly disease on citrus. The fruit will also be medicinal tasting or taste gasoline-like. This will not improve over time and therefore you should consider cutting the tree down. Of course, the decision is totally up to you. http://www.crec.ifas.ufl.edu/extension
Q: When do I fertilize and prune citrus?
A: Pruning of citrus can be done in late February and early March. Remember to selectively prune the citrus tree - no shearing. Find a growth bud, which is where a new leaf or limb will grow and cut just above it. Make the angle of the cut down toward the center of the tree and the bud should be facing toward the outside of the tree. The overall look of the citrus tree should be somewhat vase-shaped to allow for good air circulation throughout the tree canopy. Do not be afraid to keep the tree short to assist you with picking fruit. Fertilization should begin in March and occur about once every 6 weeks through September. Allow the tree to produce and mature the fruit from October through February and refrain from applying fertilizer during those months. You may use a general garden fertilizer such as 6-6-6 or 8-8-8, a “citrus” fertilizer or a slow release type of fertilizer – the most important thing to do is read the label to determine how much fertilizer should be applied. If you select a slow release fertilizer then it would not be necessary to apply every 6 weeks. Avoid overhead irrigation as this helps the spread of disease – water citrus at the root only. Remember when selecting citrus to choose only those trees grafted on trifoliate or Swingle root stock as they are the most cold-hardy for our area.
Q: I think I have powdery mildew on the trunk of my citrus. What should I do?
A: More than likely what you have is known as citrus snow scale, Unaspis citri, which commonly attacks the trunk of citrus. These tiny white specks are actually insects, which is very surprising as they have no legs. Early symptoms of infestation besides the snowy appearance of the woody tree portions are declining tree vigor and reduced fruit production. Continued infestations result in partial defoliation, dying limbs and branches, large cracks in the bark, and the eventual death of the tree. It would not hurt to gently remove some of the scale with a soft bristle tooth brush before applying horticulture oil. I stress the word gentle as the bark of citrus is very thin and easily damaged, so please be careful. Citrus snow scale insects are extremely tiny and they are easily transferred from one citrus plant to another. It may take more than one application of horticulture oil,
Q: What is wrong with my citrus tree? I see little white flies whenever I get near the fruit or leaves. I turned some of the leaves over and saw these orange specks. Is this an insect or a disease?
A: Actually the orange spots you see are neither an insect nor a disease. The spots are beneficial fungi which attack the young stationary stage (pupae) of a common citrus pest called the white fly. The white fly is an important pest of many fruits and vegetables as well as ornamental plants. In large commercial plantings of citrus, citrus whitefly and cloudywinged whitefly are largely controlled in rainy weather by whitefly fungi. Some important species are the red fungus (Aschersonia aleyrodis Webber) and the brown fungus (Aegerita webberi Fawcett). A yellow fungus, Aschersonia goldiana, does not attack the citrus whitefly, but is very effective against the cloudywinged whitefly. The presence of the yellow fungus guarantees that cloudywinged whitefly is present. These fungi are generally present in all citrus groves in Florida and increase in numbers when the proper environmental conditions prevail. These fungi are commonly referred to as "friendly fungi," and the two major species are often referred to as red Aschersonia and yellow Aschersonia. This is another example of leaving things alone and letting nature take its normal course of action. We would not recommend any chemical application as the fungi are probably managing the white fly population quite well. This information was taken from a publication titled, “Your Dooryard Citrus Guide: Common Pests, Diseases and Disorders of Citrus” by James J. Ferguson from the UF/IFAS http://edis.ifas.ufl.edu/pdffiles/HS/HS12200.pdf
Q: What could be eating the leaves on my citrus tree? The fruit are not being touched. Should I be worried?
A: There could be several creatures eating the leaves of your citrus trees. It is possible a katydid or a grasshopper are snacking on the leaves. The katydid, although very large in size, looks so much like a leaf you could easily miss them. I captured both a male and female chomping away on one of my trees. They are now resting comfortably in my insect collection box side by side. Growth regulators work well on these creatures or you can use the tried and true method of hand picking and squashing. However, finding the katydids did not end the mystery of the missing leaves on my citrus. I kept looking for the culprit. The formal word for this process of hunting for insects or disease is called “scouting.” As I am scouting I come upon another strange looking caterpillar. I do not kill this strange looking caterpillar immediately because I realize he will become a beautiful butterfly in the near future. The few leaves he eats will not reduce the number of oranges my tree produces nor will it destroy the tree. Therefore, I do nothing. I am rewarded immediately for my kindness by spotting a new arrival spreading its wings along the pine straw. It is a giant swallowtail butterfly, Papilio cresphontes Cramer. It is very vulnerable during this time as it cannot fly well enough to escape any predators. Like all newly emerged butterflies, the wings must wait until the blood has completely filled all the veins. This process takes a few minutes but I have a wonderful opportunity to take its photograph. The butterfly is frightened by my camera and flutters a short distance but it cannot really escape. You can see one corner of the wing is curled as the blood has not completely reached this area forcing the butterfly to sit still and wait. If you see gray and white (ugly) caterpillars feeding on your citrus, remember what they ultimately will become – these beautiful pollinating butterflies. So, for the typical home grown citrus grower, these caterpillars are a nuisance but not a real worry. However, it is a different story for the commercial grower who has millions of dollars invested in citrus fruit production. The commercial grower is facing several devastating diseases and therefore cannot risk having his crop diminished even by such a charming insect as a butterfly larvae.
Q: When do I prune my citrus?
A: In general, homegrown citrus trees do not need formal pruning. If, however, you wish to rejuvenate the tree then light pruning should occur just before a major growth flush. Broken, cracked or diseased branches can be removed anytime. This photo shows the proper pruning cut to make on large citrus tree branches.The following is the complete University of Florida/IFAS publication on pruning citrus: http://edis.ifas.ufl.edu/HS121
Q: My citrus fruit is splitting. Why?
A: Citrus fruit splitting could be a combination of several factors. If the tree is allowed to produce too many fruit then the quality of those fruit is often poorer than if fewer fruit were allowed to develop and mature. Heavy fruit loads often produce thin skinned fruit which can readily split under specific weather conditions. Combine the heavy fruit loads with inconsistent watering and/or heavy rains and the skin of citrus can crack and break. Low potassium levels in the soil have also resulted in citrus fruit splitting. Once the fruit splits, nothing can be done to repair it. However, if the fruit is mature and fully ripened, it is safe to eat. The best prevention of fruit splitting is to fertilize and water properly and reduce the number of fruit allowed to mature. It is much better to have 30 sweet, tasty oranges than 100 of reduced quality. This is a wonderful example of “less is more.”
Q: Citrus problems such as leaf drop, fruit drop, non-blooming or fruit split. What can be done?
A: I have received dozens of questions regarding citrus tree problems so I decided to answer them all together. Citrus do not like "wet feet," meaning they prefer to be irrigated on a regular basis but do not like to have their roots sitting in water. Citrus trees have a tendency to develop root rots and little can be done to correct this problem once it develops. To assist with keeping oxygen at the roots remove mulch from around the root area and never allow it to touch the trunk of any tree or shrub. Toot rots will cause yellowing leaves, fruit or leaf drop and/or twig dieback. Other diseases can cause yellowing leaves, fruit or leaf drop and/or twig dieback. Other diseases can cause these same symptoms, but irrigating more than twice a week may be too much. Fruit splitting often indicates the fruit received too mulch water too quickly and the rind splits as a result of the sudden uptake. Keep lawn grass as far away from your citrus and any tree as possible. When the tree is young the grass will usurp most of the soil nutrients. It takes a tremendous amount of energy to produce juicy, tasty fruit, therefore removing some fruit from the tree before it matures will allow the tree to produce fewer but better fruit. It is best to do it when the fruit is small, no larger than a grape.
Fertilize citrus every six weeks when the tree is young (under 7 years) with a good quality citrus fertilizer. Avoid using fertilizer tree spikes as this only provides nutrients in the immediate area where it is placed in the ground. If you already have tree spikes, break them up and spread them under the tree canopy. Avoid fertilizing from October through February; otherwise fertilize adult trees often but in small increments. It is not uncommon for citrus to experience and occasional fruit or leaf drop.
Q: How do I protect my citrus from the freezing temperatures?
A: This information was taken from “Gardening in a Minute” which is produced by the University of Florida. The web site is attached at the end of this answer. Protecting citrus from cold temperatures is important for current and especially future crops Citrus can grow in most parts of the state, but most types require protection when cold weather rolls in. Cold protection is achieved by trapping ground heat. While covering the entire tree is best, if your tree is too large, wrap the trunk with several layers of cloth. It is particularly important to protect the area where the scion was grafted onto the root stock. Either way, make sure the covering reaches all the way to the ground and is secured. Remember to remove it when the temperature returns to above freezing. Newly pruned trees are much more susceptible to cold damage, so postpone pruning until spring. In North Florida, choose cold-hardy citrus varieties or keep the plants in containers so they can be moved to a protected area. With a little care, your tree can come through cold weather. We will be conducting a citrus pruning class on January 20th at 1pm at the home of a Master Gardener in the Callahan area. This free class will give you some good pointers on best management pruning techniques to better equip you for pruning citrus trees in the spring. If you are interested in attending please contact the Extension office at 548-1116 (Yulee), 530-6353 (Callahan) or firstname.lastname@example.org. http://gardeningsolutions.ifas.ufl.edu/
Q: At what temperatures do I need to worry about my cold-hardy citrus?
A: A hard freeze is considered 28 degrees for 4 hours or more. To be completely safe, protect young trees (under 5 years) whenever temperatures drop below 32 degrees. Be sure you take extra precaution by covering the area where the rootstock and scion were joined. Water the plant 48 hours prior to the freeze. If you tree is healthy and has been watered and fertilized properly, it should be able to survive here.
Q: I have a caterpillar that is eating my citrus trees. At first I thought it was a bird dropping then I saw several of them. What is it?
A: You have discovered the larvae or caterpillar of the Giant Swallowtail butterfly, which is also called the orange dog caterpillar. This caterpillar often feeds on citrus plants as well as Wild lime and Hop trees but it seldom causes any major damage. I allow them to chew my lime tree leaves because, so far, they have not totally defoliated it. However, I have been fighting with grasshoppers who love to chew on the foliage too and I can tell you I don’t mind crushing them. But since I recognize the swallowtail butterfly larvae is a good pollinator I would have a hard time destroying this caterpillar. In addition, I have planted a cluster of wildflowers and lantana which the adult swallowtail butterflies use as nectar plants to encourage these butterflies to visit my lawn.
Q: What is wrong with my citrus leaves and new stem growth?
A: I have received nearly a dozen calls on this same problem and although I have addressed it in this column before, it appears to be worth repeating. First, we don’t recommend you bring citrus problems to the extension office because of the ease in spreading citrus canker. However, all the samples brought into the office were in sealed freezer bags and I could easily diagnose the problem through the bag. The leaf problem is caused by a small leafmining moth, Phyllocnistis citrella Stainton, or the citrus leafminer (CLM). Citrus leafminer (CLM) was found in late May 1993 in several citrus nurseries in south Florida. Since that time, CLM has been found everywhere in Florida where citrus is grown, and has spread to other Gulf Coast areas. Adults of the CLM are minute moths (4 mm wingspread) with white and silvery iridescent scales on the forewings, with several black and tan markings, plus a black spot on each wingtip. Adults generally are so small in fact, that people barely notice them. They are active mostly during the day but have been known to continue their normal activities in the early evening hours. Adults live for only a few days but in Florida generations are produced about every three weeks. They are not easily controlled using chemicals as they burrow between leaf and stem tissue and are therefore protected. Infected leaves and small stems should be pruned, bagged and destroyed to help manage the insect populations. A predatory wasp, encyrtid parasitoid, Ageniaspis citricola, was introduced from Australia to Florida in 1994-95, and seems to have the key element in suppressing this leafminer to an acceptable level.
Q: How do I know if my citrus fruit is ripe?
A: Your question is timely for this time of year. It is difficult to give you specific time to know when your fruit is ripe because that differs per species and even per area. For instance, grapefruit ripens between November and March whereas many oranges ripen between October and January. Citrus fruit will not ripen after it is picked like apples or pears because citrus has no carbohydrate reserve so don’t pick it too early. The best way to know when your citrus is ready to eat is to try one fruit at a time until you can taste that it is mature. When you see the fruit wrinkle that is your indication it has been left too long on the tree. Please check out the University of Florida publication titled: Growing Citrus in the Dooryard at http://edis.ifas.ufl.edu/XC005.It will have specific information regarding caring for citrus in Florida plus you will see a table giving you times to expect your fruit to mature.
Q: I have a citrus tree and the leaves are curling, dropping off, and they look pale. What is wrong with my tree?
A: I am glad you brought a clipping of the tree to me. After examining it closely, I could see the culprit was a citrus mite. The citrus red mite or purple mite, Panonychus citri (McGregor), was first recognized as a pest of Florida citrus in 1885. From the late 1930s to about 1960, it reportedly was one of the most serious economic pests in Florida citrus. Today, growers find this mite to be a sporadic pest. Citrus red mite populations are usually greatest on lemon and grapefruit, followed by orange and then tangerine. Infestations may develop any time of the year, but generally occur between November and June. Peak infestations usually occur in May or June following the major plant growth cycle of new spring flush or when prolonged dry conditions occur. Some citrus varieties such as lemon, lime and grapefruit have several minor flushes of new growth throughout the spring, summer and fall in Florida. This allows spider mites to increase depending upon favorable weather conditions. Citrus red mite prefers green developing fruit to the more mature yellow fruit. The influence of undetermined numbers of citrus red mites and weather can result in heavy leaf drop, twig die-back and even death of large limbs. Usually there is no direct effect on fruit quality although fruit drop due to heavy infestations can occur. Reducing or eliminating pesticides such as copper, copper plus oil, sulfur and lime sulfur can prevent citrus red and Texas citrus mites from flaring and becoming serious pests.
Q: What is wrong with my grapefruit? Can I eat it?
A: I believe you have a disease called Greasy spot or Greasy spot rind blotch (GSRP). Greasy spot is caused by a fungus and commonly found on grapefruit, Hamlin oranges, and tangelos. Greasy spot rind blotch (GSRB) is particularly problematic for fresh fruit grapefruit and this occurs on the rind of the grapefruit as the spots join to form larger areas called blotches. The spores from the fungi produce in the decaying leaf material from the tree. The spores are taken up by the wind and attach to the underside of the grapefruit leaves forming black spots with yellow halos. When the weather conditions are perfect (moist and warm) the spores multiply causing damage to the leaves and ultimately the fruit rind. The highest levels of spore production usually occur during the months of April through June causing infection to occur from June through September. Best management practices for controlling the disease is to be sure to clean up leaf litter from under the tree and apply horticulture oil and/or copper once in mid-May to June with the second application in late July. Although the rinds of the fruit look poor, the fruit is still edible.
Q: The peeling of my grapefruit on my citrus tree is brown and it feels like sand paper. They are ripe and mature but what is wrong with them?
A: The disease is probably melanose, which is a common coastal fungal disease that primarily occurs in grapefruit but can attack any citrus. The first symptoms on leaves are small, circular, dark depressions with a yellow margin, similar to canker. Later, the spots become raised and turn dark brown. The leaves may turn yellow and may drop prematurely, which can also be a symptom of other disease or insect problems. Raised spots can are also be found on twigs, which may result in twig die back. These spots can also occur on the fruit, which is why your fruit had the sand paper feeling on the rind. The disease can be severe following rainy periods in the spring, particularly when such periods follow a freeze that has left an abundance of dead twigs. This disease is also common on older, neglected trees. Copper sprays are usually applied 2-3 weeks after petal fall and a second spray 2-3 weeks later. With a particularly wet spring, a second application may be needed. Citrus should be sprayed for melanose control in the spring following a freeze. Be sure to use a fungicide specifically formulated to be used on citrus. Follow the directions on the fungicide label; remember "the label is the law". The best melanose management strategy is to remove small, dead twigs, and avoid overhead irrigation. If you are concerned about citrus canker you can call the hotline: 800-904-3781. Please do not bring in diseased citrus specimens into the county extension offices or local garden centers.
Q: Why isn’t my ruby red grapefruit blooming? It gets some sun in the afternoon and I have used stake fertilizers each year. I am watering it twice a week just like my lawn grass. It looks healthy, and is growing, but still no fruit.
A: Some grapefruit varieties are notorious for taking 7-12 years before they are mature enough to produce fruit – so be patient. However, you might consider moving it to a site that gets full sun, 6-8 hours is best. Any plant (lawn grass, trees or shrubs) will generally need less water and fertilizer when they are in shaded areas. The University of Florida recommends watering lawn grass in full sun once every 5-7 days in the summer and once every 10-14 days in the winter. You are probably over watering the plants in your landscape and could reduce it. However, you should measure your irrigation systems output. Consider placing empty tuna fish cans around your irrigation zones and run the system for 20 minutes then use a ruler to measure the amount of water in each can. Your goal is to have ¾ - 1 inch of water each time you water for your lawn grass. Adjust your system so it matches the maximum output of 1 inch. Citrus also has a tendency to develop root rots so it is important their roots do not stay wet. Do not put mulch over the root area and keep lawn grass as far away from the roots as possible. Be sure to use citrus fertilizer on your citrus and granular fertilizers are preferred over stakes. The stakes are convenient but they do not reach all the roots. Broadcast the granular fertilizer all over the root area (avoid the trunk of the tree). Be sure to follow the directions on the label and look for slow release fertilizer whenever possible.
Q: I would like to grow a pink or red grapefruit here in Northeast Florida. What would you suggest?
A: Try Ruby Red or Pink Marsh. Pink Marsh is nearly seedless and can be harvested from December through May. Ruby Red is readily available at local garden centers and plant nurseries. Ruby Red is also nearly seedless producing fruit from November through May. Both cultivars are delicious eaten or used for their abundant juice. Be careful about combining grapefruit juice with certain medications. Check with your doctor or pharmacist just to be sure you will not cause a reaction if you drink grapefruit juice with your prescribed medication. Half of a medium pink grapefruit can provide 100% of your daily vitamin C requirements and still only be 60 calories. It also contains other important vitamins and minerals such as potassium, vitamin A, thiamin, niacin and magnesium. Grapefruit also contains lycopene which is thought to reduce the risk of certain cancers. Of equal importance is what grapefruit does not contain – no fats or sodium. So go ahead, eat a grapefruit without any guilt.
Q: Will you please print how to fertilize and prune lemon trees in the newspaper?
A: I am glad you wrote me and requested the information; I have had several phone calls on the same topic. I know you asked to be sure to have the answer printed in the newspaper; however I really have no control over whether things get printed. Fertilization should occur in March and go through September. No fertilizer should be applied October through February. Use 6-6-6 or 8-8-8 or 10-10-10 and sprinkle it all around the root area under the tree canopy. Apply water directly to the fertilizer to allow it to reach the root area; about ¼ inch should be sufficient. If you have purchased the spikes, crumble them up and sprinkle it all around the root area under the canopy. Don’t forget to water after the application of fertilizer ¼ inch, similar to the other fertilizers. I use a slow release general purpose fertilizer which is 10-10-10 and apply spring (March), summer (June) and fall (September). It makes it easier to remember and I will fertilize my palms at the same time. Pruning can begin in March but citrus really does not require a lot of pruning to fruit. Cut out any dead or dying limbs, which can be done any time of year. Any limbs growing toward the center of the tree should be removed and any rubbing limbs can be cut back. If the tree is too tall then consider taking a few years (3-5) to trim it back by using reduction cuts to take the tree down a foot or two at a time. You might consider calling a tree company to do it for you if the tree is excessively tall. No reason to put yourself in danger.
Q: I have Meyer lemon tree that needs to be moved because it now has a tree has gradually shaded it. As a result, it has gradually leaned, grasping for the maximum sun it can get; it only produces fruit in years of maximum sun and less rain. Question: can this tree be transplanted? If answer is yes, then 1) When?, 2) With what precautions?, 3) How much pruning? 4) What fertilization at time of transplant? Thank you again for your assistance.
A: You have seen the results of a true experiment on this plant's need for full sun. It can be transplanted and as you can see it will produce better if given full sun exposure. The best time to transplant citrus is in the spring. Get as much of the root ball as possible, dig the hole wider than deep and add nothing to the hole. Set the plant in the ground slightly (1/2-1 inch) higher than it grew in the ground. Re-fill the hole around the plant about 1/3 to 1/2 full, then water and gently tamp the soil thoroughly to remove air pockets. Allow the water to settle, fill the hole 2/3 full of soil, re-water and tamp again. Finish filling the hole and pack the soil firmly around the tree. Form a water basin around the tree at least 3-4 inches high and 30 inches in diameter. Do not put mulch over the root ball. Water 3 times a week for 2 weeks, and then taper off gradually to once a week during periods of little or no rainfall. The basin should stay in place until the tree is well established. Avoid pruning the tree prior to transplanting (this would apply to any tree or shrub); you want to encourage the tree to put its energy into growing roots. Pruning citrus should not be necessary except to shape the trees or remove water sprouts or suckers. Do not leave stubs as they may be attacked by rotting organisms which could damage the tree. Fertilization could be done in June and then again in the fall between Oct. and November. The recommended 3 applications per year can be made in January - February, May - June and October - November although timing is not especially critical. Good luck.
Q: I have brown, streaked areas on my lemon. It feels like sand paper. What is it?
A: Your description of the condition points to citrus melanose, which often occurs on grapefruit, but any citrus can be susceptible. Only the rind of the fruit is damaged; the fleshy pulp and juice is perfectly fine to eat or use in cooking. Humid, wet weather or overhead irrigation is a contributing factor because the dampness provides the fungal spores a perfect environment to reproduce and spread. The tiny spores hide and spend the winter in the dead twigs. Melanose is usually more severe in older, neglected trees and cold-damaged trees with large amounts of dead wood and twigs. The best management strategy is to remove dead branches and twigs whenever you see them. Copper sprays are usually applied 2-3 weeks after petal fall and a second spray 2-3 weeks later. Be sure you use a fungicide labeled for use on citrus and follow the directions on the label. Whenever possible, avoid overhead irrigation. Remember trees and shrubs prefer to be irrigated at the root area. Chronic wetting of the leaves promotes disease. Consider changing your irrigation heads to provide irrigation at the root area. One other note on irrigation: most established trees and shrubs do not have the same irrigation needs as lawn grass and therefore should be placed on different zones.
Q: My patio lime tree has some fruit on it even now. I am concerned about losing this fruit if we have more cold weather. What should I do?
A: Lemons and limes are “ever producers”, which means if the conditions are right, they continue to bloom and produce fruit. You obviously have this plant in a well protected area which must receive sufficient light and water. Therefore, this lime tree is happy to keep making fruit. If it has gone through temperatures in the teens and still produced fruit you have little worries. You can always cover it if temperatures drop below freezing. However, you are doing something right already so I would suggest doing nothing to alter perfection. Your patio may be a micro-climate where the temperatures are conducive to citrus production. This lime may also be on a dwarf tri-foliate root stock which is very cold hardy. All of these factors have contributed to your success. Keep up the good work; we are all envious.
Q: I am afraid my lime tree was damaged after these cold nights. How do I prune it?
A: After a severe freeze that causes damage to major limbs, wait several months to prune. During the spring flush following a freeze, leaves on freeze-damaged limbs may grow but then will wilt soon after. After this wilt occurs on the spring flush, you will have a better idea about which limbs to prune. However, limbs with minor cold damage and split bark can continue to reduce fruit production for months, and even years, after a freeze. Sometimes when a tree is weak, frozen back or broken off, a sucker or shoot will grow from the rootstock. The fruit from this rootstock shoot will be different than on the original tree. The tree may produce two kinds of fruit if a portion of the scion remains. Fruits from rootstocks may be sour orange, rough lemon, trifoliate orange, Carrizo citrange, or Swingle citrumelo or other rootstocks. Cut the sucker off to allow the desired variety to become dominant. If your tree is completely destroyed, it is usually better to plant a new tree of the desired variety than to try to bud the rootstock. If you’re thinking of moving a mature tree to a different location, it is also usually more economical to plant a new tree in the site.
Q: Currently I have a lime tree in a pot and I want to plant it outside. When would be a good time?
A: I would suggest you wait until the threat of frost is over. The final date for frost may be sometime between March 15 through April 15. Of all the citrus, limes are the least cold tolerant. Limes may show cold leaf damage when temperatures drop into the low forties. Hard freezes, similar to the ones we experience in 2009, will most likely destroy the whole tree. However, once they are established, which may take five to seven years; they should survive through most of our winters. It would be important to protect the young trees through those vulnerable early years. If the tree is small enough, cover the whole tree when temperatures go below forty. Be prepared to remove the cover when the temperature rises. It would not be beneficial for the plant to stay in darkness for any length of time. Limes and lemons set flower and fruit throughout the year as long as temperatures are warm. They normally have different stages of fruit maturing on the tree. When a freeze occurs, it would be best to remove any fruit. Some people think the young fruit will mature later but it will be destroyed by the cold. I would suggest novice home citrus growers start with a more cold-hardy citrus such Satsuma, Ambersweet orange or Limequat.
Q: This year, some of my navel oranges had dry areas in the fruit. What causes this and how can I prevent it?
A: It is always disappointing to cut open citrus and find the flesh is dry or pulpy. Navel oranges are not the only citrus to have this problem; any citrus can show the same signs. We do suspect this can occur on older trees which have not been tended, fertilized or pruned properly. This is especially true when the root stock foliage has been allowed to overgrow the scion or fruiting part of the tree. It is important to keep the root stock growth in check. In fact, if possible, check citrus several times a year to remove the suckers from the root stock. This type of growth can be removed any time of year. It is always sad to see a once strong producing citrus which has be overgrown from the rootstock. Irregular irrigation or periods of drought will also produce poorly developed, lush fruit. If you are using micro or drip irrigation then watering once or twice a week should be sufficient. Cut back on the irrigation when we receive sufficient rain. Citrus are notorious for developing root decay under heavy irrigation from the type of sprinkler heads used on typical lawns. I know your tree have been planted for several years but young trees (under 5 years) often will produce poor fruit. However, this should outgrow this tendency once the tree is established and becomes more mature. Regular fertilization is also important. Use a 6-6-6 or 8-8-8 once every 6 weeks from March through September. Do not pour fertilizer under the tree in a circle or band, but rather broadcast it completely under the tree canopy. Be sure to water in the fertilizer once it is applied; usually ¼ inch is sufficient. Or use a slow release citrus fertilizer once every quarter (March, June, September) for those of you with busy lives. When purchasing trees, be sure to ask about the root stock.
Q: I want to grow some oranges for juicing. What are the best types to grow in Northeast Florida?
A: There are two juicing oranges which grow best in our area and they are Hamlin and Pineapple oranges. Hamlin oranges are generally harvested from October through early January. Pineapple oranges are harvested from December through February. You might try a Parson Brown also which can be harvested from late October through January. Hamlin is the preferred orange for juice because it produces very few seeds. Parson Brown may have 10 – 20 seeds per orange and Pineapple oranges may have more at 15 – 25 per orange. Hamlin may have only 6 seeds per orange, but often none. I mentioned the seed amounts as they can be a nuisance when juicing any citrus. Some people have been successful in growing Valencia but these oranges mature later in the year when we often experience freezing temperatures. This puts the ability of the fruit to mature at risk. Valencia oranges also have very few seeds. Since Valencia requires a little more care, I usually do not recommend it for this area – especially to a novice home grower. For more complete information regarding growing citrus in the landscape, please plan to attend the UF/IFAS Landscape Matters class on citrus Wednesday, January 11 at the Yulee County Building, 10 am. Please contact us if you plan to attend: 904 530-6353 or 530-6350. This program is free to the public. If you cannot attend, attached is a University of Florida publication regarding citrus for home landscapes: http://edis.ifas.ufl.edu/pdffiles/HS/HS13200.pdf
Q: What is the proper timing, amount and type of fertilization for a mature orange (or perhaps tangelo) tree?
A: For mature bearing trees on well-drained soils, three applications of slow release citrus fertilizer per year are sufficient, one application in the fall or winter followed by a second application in the late spring or early summer and a third in late summer.
Q: I purchased a Mandarin Orange tree called ‘Robinson’ at a local nursery and they told me I needed to buy another orange tree to help pollinate this one or it would not produce fruit. Is that true and if so what should I use to pollinate it?
A : Many citrus trees are self-pollinators meaning they produce fruit by pollinating the blooms on the same tree. However, your orange tree ‘Robinson” does require other pollinators and you should consider using the ‘ Orlando’ tangelo as a cross pollinator. It is important to use a cross-pollinator that has a blooming period that overlaps your tree, produces a good crop of flowers, and has the same cold-hardiness. ‘Robinson’ is one of the most cold-hardy of the mandarin types but it is susceptible to limb breakage if fruit bearing is too heavy. Harvest occurs between October and December with fruit containing 1-20 seeds per fruit.
Q: I have an orange tree that used to produce sweet fruit. We pruned it back a few years ago after a freeze and now it only produces small sour oranges that are full of seeds. Is there some kind of fertilizer we can apply to the tree to make it produce the sweet oranges again?
A: I get this question often especially during the spring after a cold winter. I am afraid I have some bad news for you; there is no fertilizer you can add to the ground to make the sour oranges sweet. I suspect your original orange died as a result of the freeze and the root stock, which is probably a sour orange, is the only living portion of your citrus tree. Sour orange is a common root stock because it is so cold hardy, but as you noticed the fruit is inedible. Once the scion, the grafted portion, dies the hardy root stock will totally take over the tree. On citrus trees, be sure to protect the area where the scion and the root stock join in order for the upper scion portion to survive freezing temperatures. Even if the top portion freezes, the tree may be able to recover once temperatures become warm again. You have several options: graft another sweet orange back onto the sour orange root stock, dig up the tree and replace it, or leave the tree and enjoy it for its beauty.
Q: I have an orange tree I want to protect from the freeze. I am told I can run water over it and it will protect it from freezing but it seems like a waste of water. What should I do?
A : In order to totally protect the tree by water, you would need to start the water before the freeze and continue to water it after the freeze has passed. Although this procedure is used in citrus groves is it not recommended for the home owner. As you indicated, it is a terrible waste of water and not totally fool proof. In addition, citrus is especially sensitive to root rots which can be caused by excessive water – not a condition you want to encourage by adding too much water. Most of the oranges we grow in this area are grafted onto cold hardy root stock so there is less chance of loosing the tree from freeze damage. The portion of the tree you truly need to protect is the grafting part (where the root stock meets the scion). The scion is the upper portion of the tree which produces the desired fruit. You can place an insulating type fabric over this area during cold freezing temperatures to protect the tender upper part of the tree. Plus, you can place a fabric bed sheet or plastic over the top portion. Be sure it reaches the ground so you can trap the warm air coming off the ground to help keep the tree warm. Remove the sheet or plastic once temperatures increase above 30 degrees or once the sun comes out. Watering your tree properly prior to the freeze is also helpful. Cold frames can be built to cover the whole tree, but that should not be necessary for citrus trees grown here.
Q: Do you know of anyplace where I can get some osage oranges? It is supposedly also referred to as monkey balls. I read online somewhere that they are an excellent deterrent to spiders and ants.
A: You can purchase Osage Orange, Maclura pomifera, at any local garden nursery; if they do not have it they should be willing to order it for you. I could not find any educational reference to its ability to deter spiders or ants. This deciduous North American native tree rapidly grows 30 to 40 feet tall with a spread of 20 to 40 feet and creates a dense canopy, making it useful as a windbreak. Young trees can develop an upright, pyramidal habit. The large, three to six-inch long by two to three-inch-wide, shiny, dark green leaves turn bright yellow in fall before dropping, although this color change is not quite as noticeable on trees grown in the southeastern United States. The bark is deeply furrowed and has an orange tinge to it, and the strong, durable wood is bright orange in color. Osage oranges are considered reclamation plants that have been successfully grown in urban areas where air pollution, poor drainage, compacted soil, and/or drought are common.It is reported that the Osage Indians made their hunting bows from this beautiful and hard wood, and it is also used to make furniture. From April to June, Osage-Orange puts out its inconspicuous green flowers but these are followed by the very conspicuous fruits. The fruits are four to five-inch-diameter, rough textured, heavy green balls which ripen to yellow-green and fall in October and November. These fruits are not edible, the juice acid and milky, but squirrels relish the small seeds buried inside the pulp. When the fruits drop, they can be very messy and, for this reason, male, fruitless trees should be selected if you plant this tree. Osage-Orange is thorny, just like true citrus trees, and forms thickets if left to grow on its own. However, there are thornless cultivars available. Osage-Orange should be grown in full sun on well-drained soil. This tough, native plant can withstand almost anything once established - heat, cold, wind, drought, poor soil, ice storms, and even some vandalism. It appreciates regular watering when young until it is established, which generally takes about 4 months. The thornless, fruitless cultivars include ‘Witchita’, ‘White Shield’, and ‘Park’. Propagation is by seed, cuttings, and root-cuttings. Young trees are easily transplanted. It has no pests or diseases of major concern.
Q: My Satsuma tangerine tree is loaded with fruit but none of them are orange. How do I know when they are ready to pick?
A: Satsuma mandarin bears its fruit early in the year which makes it a good choice for our area, especially for the home landscape. The name Satsuma comes from a specific province in China. Since the fruit matures before we generally have any freezes we can avoid losing fruit when the winter season arrives. You have to try a few of the fruit to determine when they are ready. Satsuma fruit do not stay well on the tree, so it is best to pick them quickly once you know they have ripened. The mandarins grown in our area often mature internally before the external rind changes color – therefore most will have green rinds. This is also why people occasionally think this fruit tree is a “sweet” lime when it is actually a tangerine. Once the fruit is picked, Satsuma fruit can be stored for several days and still remain tasty. Most Satsuma citrus are used for juicing except for those of us growing them in our yard. Some Satsuma fruit can be found in specialty stores sold under the name “Emerald Green” tangerines. The fruit apparently does not ship well or hold up for long periods in a grocery store which is why we seldom see it in the produce aisle of our major grocery chains. However, it is a sweet orange, easy to peel and it is cold tolerant. These are just a few reasons why Satsuma is a perfect choice for the novice backyard citrus grower. Remember to stop fertilizing any citrus tree in Northeast Florida from October through February. When selecting a fertilizer for citrus consider using 6-6-6 or 8-8-8 as citrus will need Nitrogen, Phosphorus and Potassium in equal amounts to produce the best fruit possible. Do not over water, plant in well-drained soil but water on a consistent basis to avoid stress or fruit split. Attached is a publication by the University of Florida on Satsuma orange. http://edis.ifas.ufl.edu/ch116