By Julie Christensen
When properly planted and cared for, orange trees don’t suffer a lot of disease or insect problems. Preventing frost damage is often the most pressing issue, depending on where you live, because orange trees can’t tolerate temperatures much below 32 degrees, depending on the variety.
If you live in U.S. Department of Agriculture plant hardiness zones 8 through 12, you can grow orange trees successfully. Not only do these trees yield delicious fruit, but they make beautiful landscape trees with their glossy, green leaves, fragrant flowers and bright fruit.
Below, we’ve outlined some of the most common problems orange trees suffer. Keep your trees healthy and vigorous with proper care and you’ll experience fewer issues. Plant orange trees in light, well-draining soil, in full sun. A protected area near the house is ideal if you occasionally get cold spells. Water orange trees throughout the growing season and fertilize them according to the results of a soil test.
Diseases of the Bark and Trunk
Psorosis Bark Scaling Virus Disease. This disease causes patches of scaling or peeling bark on the trunk and branches. It is most common in older trees. Unfortunately, there is no cure. Continue to care for the tree properly to maintain health. If the tree becomes girdled, it will die and should be removed.
Foot Rot Fungus. Lesions and cankers around the base of the tree usually indicate foot rot fungus, especially if the lesions ooze sap. This disease is not treatable. Remove and destroy infected trees. To minimize the risk of foot rot fungus, plant trees in well-draining soil and avoid overwatering them. Raised beds and berms are necessary if you have heavy clay soil.
Sooty Canker. Twigs and branches of trees infected with sooty canker develop peeling bark. Underneath the bark, you’ll find a black fungus. The leaves may turn brown and wither and the twigs may die back. To control sooty canker, remove all infected branches. Cut them back 12 inches behind the infected area and disinfect your tools between cuttings by dipping them in a solution of one part chlorine bleach to 10 parts water.
Diseases of the Leaves
Sooty mold. Trees affected by sooty mold have blackened spots on the leaves. Sooty mold is not really a disease, but a fungus that feeds on the honeydew left behind by aphids and leafhoppers. Wash the spots off with a gentle soap and water solution. In most cases, aphids and leafhoppers leave on their own, especially if your garden has plenty of predatory insects like ladybugs. In severe infestations, though, you can try spraying the leaves with a steady stream of water or with an insecticidal soap or oil. Completely treating an orange tree is difficult, though.
Tip or Marginal Leaf Burn. Yellowing at the tips or edges of the leaves usually indicates excess salts in the soil, rather than a disease. To alleviate this problem, flood the soil several times each year to help dilute and leach out the salts.
Citrus Greening. This bacterial disease is spread by the Asian citrus psylid and causes yellow mottling on the leaves. You might also notice that the midvein seems enlarged and pronounced. There is no cure for this disease, although proper care can help the tree survive.
Cigar Leaf Curling. Wilted, curled and brittle leaves usually indicate the tree isn’t getting enough water. Install at least three drip irrigators under the tree. Water frequently during dry weather so the soil is moistened to a depth of 2 feet beneath the surface.
Diseases of the Fruit
Citrus Stubborn Disease. This disease causes lopsided fruit, with the seed pocket on one side of the fruit, rather than in the center. The disease is spread by leafhoppers. Spray infested trees with insecticidal soap or oil to treat the leafhoppers.
Alternaria Black Fungus. This disease causes a black fungus to grow inside the fruit. There is no control for the disease, although it is more prevalent after rainy weather. Discard the affected fruit, as well as leaf litter.
Fruit Splitting. This frustrating condition causes the fruit to split open before it is harvested. Fruit splitting is caused not by a disease, but by inconsistent watering and fertilizing. To prevent this problem, water orange trees deeply every one to two weeks, depending on growing conditions.
For more information, visit the following links:
Diagnosing Home Citrus Problems from the University of Arizona Extension
Identifying Citrus Tree Diseases from the University of California Davis IPM
Julie Christensen learned about gardening on her grandfather’s farm and mother’s vegetable garden in southern Idaho. Today, she lives and gardens on the high plains of Colorado. When she’s not digging in the dirt, Julie writes about food, education, parenting and gardening.
the leaf on the orange tree is curled up a little and it has these brown marks as if a worm was crawling in it. and the fruit of tree always has black on them.
my orange tree is 2y old and have the same problem as the Pamela need a solution .
Don DeLany says
I have a Saxton navel orange tree that is five years old.The tree this year bloomed/set fruit My problem is the orange did not fill out in the skin / and one half the orange was dry ! What is my problem ,and how to correct it ????? Thanking you in advance,Don
Hi Don DeLany,
The awesome valuable information you share about the foot rot fungus disease comming in the trees of orange ,If you want to remove this kind of disease comming the orange trees located in the farm of orange ,Then the best option for you to remove the Foot Rot Fungus from the trees of a orange by providing a pure water daily at morning time to all the orange trees of a lawn and also spray a medicine of foot root fungus which is help you to remove the diseases of Foot Rot Fungus comming in the stems of a trees from all trees of a garden quickly and increase the beauty of a garden .
connie neuman says
have a red orange tree the brand new leaves that came out the under side a long trailing worm in a thin coating over the top of it looks like one continues worm
dorothy a green says
my orange tree is black all over what can I do to save it
abdur Rehman says
1) i have orange garden in pakistan please i have problems in the orange at the time of bloom
more drooping of flower in the season.
2) when its bring fruits at the last stage of fruits again its start drooping of big fruits .
please give me some suggestion
Hi, I have two orange trees. I noticed today that the branches especially the new growth are covered in raised black bumps that have a hard outer shell and are sticky looking underneath . Leaves look healthy and just finished fruiting recently.
I’ve looked it up the closest match I can find is something that magnolias get If anyone one has any idea what this is and how to treat it I would be very grateful
Sounds like a parasite called Scale. May need a systemic Tree and Shrub Formula. Try the Bayer brand (it also has food) or any which have Imidacloprid or Clothianidin. I’d err on side of caution and not ingest the next harvest of fruit after treatment.
Jeff C says
I bought an orange tree for my mother several years ago. It hasn’t ever produced fruit that can be eaten.
I have no idea how to fix it!?
Sorry,the budded part has been tempered,or is not budded
My orange tree has new growth where the branches are fat and mutated looking. Older groth has flowers not the new. Any idea what is wrong I live in Australia
John Marrone says
I have sap seeping at the bottom of my orange tree. How do I fix this.
Don johnson says
I have a navel orange tree . It produces juicy and sweet fruit, but the peeling turns brown. The fruit is still good, it’s just ugly . What is causing this and how can I get rid of it? Don Johnson. [email protected]
I believe it is orange rust mite. It does not hurt the fruit, but the peel looks unattractive. You can help to prevent it by spraying the tree with neem oil. You should do this when the fruit is just beginning to form, for the first three months. This means wait awhile after the blossoms disappear and you begin to see little green oranges first. Then spray the neem oil thoroughly on every fruit you can see, once each month. The rust mites should be gone after that. You also want to make sure your tree is as healthy and well-maintained as possible, to maximize its disease resistance. Be sure it is watered consistently, especially if you live where there are dry spells. Preferably see that it gets a good soaking at least once a week, also do periodic soil tests to ensure it is appropriately fertilized.
My orange tree has round hard nodes with dense knobby bumps on the limbs and branches, dark green in color. It is around 20 years old and isn’t producing much fruit anymore. Is it treatable? I live in the Southern California coastal area.
Did you get an answer because our tree had the exact same thing. It was so bad we pulled the tree out and carefully threw it away. Also in So Cal.
We just bought a house with two orange trees but I know something isn’t right with them. There are rotten/petrified oranges up top that won’t drop but new ones starting to come in below. Plus some branches look like they need to be pruned. Help!
I have an orange tree that have given me great fruits for years. Over time I saw one of two big fruits like massive growing on one side of the tree. Now that has expanded and I get more massive fruits. Instead of getting my great oranges now half of my tree is producing these Monsters oranges that are not eatable. Did I lost this tree and need to replace it?
Hi I have tangerine tree in orange tree might orange tree the leaves are pale and I have some fuzzy looking green stuff growing on the branches what Kennett be in and my tangerine tree has the same thing starting on it now but that don’t look fuzzy it’s just is green what can I do are they savable or do I have to pull them up
jen mangan says
my valencia orange tree is loaded with fruit, some are editable but others drop and get green mold,
John Liu says
I just bought a 10-gallon navel orange plant from a nursery in early May in Houston Texas area. It is strange the plant just started to grow new leaves so late. Presumably, it should start to see small fruits for normal orange trees in May. What is the problem? Should I keep it or return to the nursery? Thank you very much!
Use resistance varieties
And also sorry with appropriate fungicide