How To Identify And Treat Citrus Tree Diseases And Insects (2022)

Citrus Tree Diseases

Greasy Spot

Greasy spot is a fungus, known as Mycosphaerella citri, that affects the leaves of citrus trees and thrives in tropical and subtropical climates. The fungus appears as yellow, dark brown, or black lesions that initially occur on the underside of mature citrus leaves. As the fungus develops, the spots become visible on the leaf top. Citrus tree leaves affected by Greasy Spot will fall prematurely, which adversely affects tree health and yield. Once established, citrus Greasy Spot can also infect the fruit and produce rind blotch, more common on grapefruit trees. Collecting and removing fallen leaves can help control Greasy Spot. You can also spray with Liquid Copper Fungicidein June or July, with a second spray application in August or September. This will help protect late summer growth from the onset of the Greasy Spot fungus.

Melanose

Melanose is a fungal infection of young citrus fruit caused when spores produced by the asexual stage of the disease (Phomopsis citri) grow in dead tree wood and twigs, and then spread to leaves under cool, wet conditions. From there, the fungus can infect young citrus and create blemished fruit. The disease affects grapefruit more readily, but is not limited to grapefruit alone. Melanose is a cosmetic citrus disease that affects the appearance of the fruit, but not the fruit quality or ultimate citrus tree health. The disease is generally more severe in trees over ten years of age. Punctual pruning is an effective way to prevent Melanose, especially when dead twigs and branches are caused from freezing temperatures. Liquid Copper Fungicide spray during temperatures below 94 degrees Fahrenheit can prevent Melanose, but may cause existing blemishes to darken. Strobilurin-containing fungicides are also effective to control Melanose, and can be applied at any time.

(Video) Identification and Management of Common Citrus Diseases and Disorders in the Home Landscape

Citrus Canker

Citrus Canker is a bacterial infection caused by the pathogen Xanthomonas citri. This pervasive citrus tree disease creates circular lesions, or scabs, on citrus fruit, leaves, and twigs. Newer lesions are yellow, and more mature Citrus Canker lesions become brown. Citrus Canker is highly contagious and can be transmitted by wind-blown rain, or mechanically by pruning equipment, ladders, vehicles, and clothing. Citrus Canker causes necrotic dieback, tree decline, premature fruit drop, and blemished fruit. There are a variety of sprays designed to protect citrus trees from Canker infection, such as Liquid Copper Fungicide as a preventative treatment. However, already infected trees should be removed and destroyed to prevent further contamination from the contagious Citrus Canker disease.

Root Rot

Root Rot (also known as Brown Rot or Collar Rot) is a citrus tree disease caused by the soil-inhabiting fungus, Phytophthora. Root Rot symptoms include dark brown or black patches of hardened bark on the tree trunk, mainly at the base. It is also common for ooze to seep from the affected area. As citrus Root Rot advances, tree bark dries, cracks and dies. The infected area is then left as a dark sunken crater, or indention. As Root Rot progresses, it can cause the fruit to become brown and slowly decay. Leaves may also turn yellow and drop. Root Rot fungus exists in the soil and thrives in wet conditions, such as periods of flooding or excessive rainfall. The disease can then migrate to the tree from splashed or windblown dirt. To prevent citrus tree Root Rot, remove all decaying material such as leaves, dead weeds, and fallen fruit from the ground surrounding the tree base, and prune lower limbs to at least two feet above the ground. Spraying citrus trees including limbs and trunks with fungicide will also control Root Rot.

Sooty Mold

(Video) How to Control Pests & Diseases on Citrus Trees

Sooty mold is a black leaf fungus that is the symbiotic result of mold forming on leaves where honeydew secretions from insects like whiteflies, aphids and mealybugs provide the ideal nutrition and harborage for the fungus to grow. Therefore, controlling those insects is the most efficient way to control Sooty Mold on citrus. Spray citrus trees with insecticide formulated to control whiteflies, mealybugs, and aphids, and be sure to spray both the top and undersides of the leaves. To control and eliminate established Sooty Mold, spray the tree with Liquid Copper Fungicide.

Citrus Tree Insects & Pests

Citrus Whitefly

The Citrus Whitefly (Dialeurodes citri) is a small fly that is dependent on new citrus foliage growth for development and reproduction. Citrus Whiteflies feed on the underside of citrus tree leaves, and will take flight in swarms when an infected branch is disturbed. Whitefly larvae create honeydew when sucking sap from leaves, which in turn creates Sooty Mold, and attracts other insects. Several generations of Citrus Whitefly can propagate over a single growing season. Since adults fly, it is difficulty to control an entire Citrus Whitefly population. Therefore, insecticide spraying to control Whitefly juveniles is the most effective means of treating infected citrus trees.

Aphids

Aphids are tiny insects and nearly all individuals are egg-laying females that produce live young. Males are only needed to produce over-winter capable eggs, so hatching and growing Aphids can create rapid infestations. Because of this, Aphid populations can grow quickly and cause serious damage. Aphid outbreaks are especially fond of succulent new growth. Aphids attack the tree by sucking the sap from leaves. An affected citrus tree will quickly form curled leaves, leaf yellowing, colonies of aphids, and the attendant dripping honeydew will become visible. This can attract ants, as well as Sooty Mold. Eventually leaves will die, and twigs will rot and fall off. Aphids can be controlled using insecticides and insecticidal soap on infected areas, and treating both tops and undersides of leaves, and all branches and twigs.

Citrus Thrips

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When a tree is infected with Citrus Thrips the most visible sign of the infestation is curled, enclosed, or shriveled leaves. Citrus Thrips are tiny orange, yellow, or even black insects that can attack trees at any age. Thrips attack young leaves and juvenile fruit and feed on the citrus tree sap. Adult Citrus Thrips lay eggs in the fall and the juvenile insects hatch in spring. To control Citrus Thrips spray the tree with Garden Insect Spray with Spinosad. Repeat spray applications may be required every two weeks. Keep the tree well irrigated and property fertilized, because a vigorous tree is less susceptible, although not immune, to Citrus Thrips.

Orangedog Caterpillars

The Orangedog Caterpillar is a large, brown, green, and white caterpillar about two inches long. The markings create a clever mimic of bird droppings, and an effective deterrent to predators. The Orangedog Caterpillar is the juvenile stage of the black and yellow swallowtail butterfly, common throughout Florida and the tropics. The adult butterfly lays her eggs on new citrus leaves and, as the eggs hatch and new caterpillars emerge, they consume leaf flesh. In sufficient numbers Orangedogs can defoliate an entire tree. To control the Orangedog Caterpillar, physically remove and destroy the caterpillars by hand. When disturbed, the caterpillars may push out two red horn antennas from just behind their head that emit a strong, foul smell. Severe Orangedog Caterpillar infestations can be controlled by spraying with an insecticide that contains either Spinosad, or Bacillus thuringiensis (BTK). Both insecticides are made from naturally occurring bacteria. Spray the entire tree. It is possible that a second spraying may be required in a month or so, depending on the severity of the infestation.

Snails

Snails will eat leaves, fruit rinds, and sometimes, citrus tree bark. Snails can be detected visually, or by spotting the damage created as they feed. Snails use leaves on the ground for breeding grounds and as cover. Therefore, to control snails, it is important to remove fallen leaves and fruit from around and under the trees. Also, it is a good idea to prune any low branches that may touch the ground, to keep snails from easily accessing citrus tree interiors. Slug and Snail Bait can be applied to the soil surface to control snail growth and movement.

Brown Soft Scale

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Brown Soft Scale is caused by a small insect that attaches itself permanently to citrus tree branches, trunks, leaves, and fruit. Brown Soft Scale insects suck sap from the tree and cause leaves to yellow then drop. Brown Scale also produces honeydew secretion that is conducive to the growth of Sooty Mold.

To control Brown Soft Scale insects, spray horticultural oil to suffocate the scale and eggs. Crawling nymphs only emerge in early summer, so trees can be treated with insecticides at that time to prevent further infestation.

Citrus Bud Mites

Citrus Bud Mite is a tiny, elongated insect that mainly attacks lemon trees located in coastal areas. The lemon blooms are very susceptible because the Citrus Bud Mite attacks the delicate blossom and new leaves, feeding on sap. To control Citrus Bud Mites spray the tree with insecticide such as Bug Buster or Trounce.

Citrus Red Mites

Like Citrus Bud Mites, Red Mites are tiny insects that feed on new growth and sometimes even fruit. The Citrus Bud Mite is red or purple and often inhabits the underside of mature leaves, or the delicate folds of emerging foliage. Severe infestations can cause leaf drop, low yields, and poor tree health. To control Citrus Bud Mites spray trees thoroughly with insecticides such as Bug Buster or Trounce.

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FAQs

What is best spray for disease on citrus? ›

10 Best Insecticides For Citrus Trees – Reviews & Top Picks In 2022
  • Espoma Organic Earth-tone Insecticidal Soap. ...
  • Southern Ag Malathion-Oil Citrus & Ornamental Citrus Concentrate. ...
  • Safer Brand Insect Killing Soap Concentrate. ...
  • Ortho MAX Malathion Concentrate Insect Spray. ...
  • Monterey Horticultural Oil Concentrate.
23 Feb 2022

What do you spray on citrus trees? ›

Horticultural oil sprays will control both citrus red mites and two-spotted spider mites. Apply a horticultural oil spray before new growth begins in the late winter or early spring and when the temperature is above 45 °F.

What diseases do citrus get? ›

What does fungus look like on a lemon tree? ›

Greasy spot fungus – Greasy spot is a fungal disease of lemons whose symptoms include telltale yellow-brown blister on the underside of the leaves. As the disease progresses, the blisters begin to look oily. Treating this lemon disease also requires an application of liquid copper fungicide.

How do I protect my citrus trees from insects? ›

To protect your citrus plants from scale insects, mix 1 cup of olive oil, ½ cup of water and 3 drops of detergent and spray the undersides of the leaves. This smothers the bugs and they should die.

Can I spray soapy water on my lemon tree? ›

You can spray any of the following to help get rid of pests naturally: Essential oils. Soapy water. Neem oil.

When should citrus trees be sprayed? ›

Dormant Oil: Apply when trees are dormant, November through March, after all the leaves have fallen. Mix with water as directed and spray to all surfaces of the trunk, branches and twigs. Apply when the temperature is expected to rise during the day; temperatures below 35 degrees can damage the bark.

Is Epsom salt good for citrus trees? ›

Because Epsom salt is a form of magnesium, it is an effective and convenient soil amendment for treating magnesium deficiency in lemon trees. It is important that your lemon tree has enough magnesium in order to thrive and produce fruit for years to come.

What can I spray on my lemon tree to keep bugs away? ›

Horticultural oil sprays are also effective in treating pests of lemon trees known as citrus rust mites. These are insects that affect lemons, for the mites attack immature fruit. They can also attack foliage and leaves in some cultivars. Repeated oil sprays will get rid of insects on lemon trees.

How do you treat citrus blight? ›

There is no cure for citrus blight. Aggressive pruning of an infected plant will temporarily halt the infection, but the measure is only temporary and the plant will eventually decline. Rates of citrus blight infection can be reduced by growing citrus-bearing trees on rootstocks that are tolerant to the disease.

How do you treat citrus rust mites? ›

Citrus Rust Mite - YouTube

Can you use neem oil on citrus trees? ›

Neem oil is safe for citrus trees as it is a natural pest repellent that won't cause any side effects if used correctly. You can apply neem oil on citrus trees as an insecticide, pesticide, or fungicide. Neem oil is a great natural pesticide for common citrus tree pests.

How do you save a citrus tree? ›

To revive a dying lemon tree, replicate the conditions of its native Mediterranean environment with full sun, moist soil with good drainage, protect the tree from wind and use a special citrus fertilizer to ensure the lemon tree has the nutrient it requires.

How do I get rid of spider mites on my lemon tree? ›

Destroying the Mites

If you see webbing on leaves, spray the tree thoroughly with insecticidal soap, which destroys mites. Dilute the soap at a rate of 6 tablespoons for each 1 gallon of water in a garden sprayer and spray all sides of the tree's leaves until they're dripping wet.

Can you spray vinegar on citrus trees? ›

Both citrus trees and avocado trees are tolerant of acidic and alkaline soils, but if your soil is prone to being too alkaline you can make it more acidic slowly by adding vinegar to the soil. The vinegar will not overly acidify your soil.

When is the best time to spray orange trees? ›

You can wait a bit longer in the spring to use this spray, but do so before the leaves have opened. These general purpose fungicides should always be used when the daytime temperatures are steadily around 60 degrees F.

What to spray on orange trees for bugs? ›

Mix 1 teaspoon vegetable oil, 1 teaspoon plain dishwashing liquid and 1 cup of water. Spray the solution over the tops and undersides of the leaves, and rinse with water after a few hours. Test both the soap and oil solutions on a small area of the orange tree before you spray the whole tree.

How do you make a spray for citrus trees? ›

Organic Homemade Recipe Zaps Insects From Your Citrus Tree

How do you make homemade pesticides? ›

Oil Spray: Mix 1 cup of vegetable oil with 1 tablespoon of mild liquid soap. Add 2-8 teaspoons of this mixture to 1 quart of water and spray your plants as above. The oil in this spray smothers the insects so it is effective on aphids, thrips, mites, and scale.

What kills citrus aphids? ›

Aphids multiply quickly. Their population can be reduced by washing trees with a forceful spray of water. Do this every one or two days for about a week.

Can you spray vinegar on fruit trees? ›

Dealing with Unwanted Plant Growth at Base of Fruit Trees

According to the "Dirt Doctor," Howard Garrett, one of the best herbicides you can use is a spray prepared by using 1 gallon of 10 percent vinegar, 1 ounce orange oil, 1 tbsp. molasses and 1 tsp. dish soap. Do not add water.

How do you make homemade fruit tree spray? ›

Experts at Oregon State University recommend mixing 1 teaspoon of vegetable oil and 1 teaspoon of dishwashing soap per cup of water. This spray will help with aphids, mites, scales and other insects that have very small breathing holes.

What kills fungus on fruit trees? ›

Systemic fungicides like Inspire Super, Vangard, Scala, Flint, Sovran, Merivon, Pristine, Luna Sensation, Luna Tranquility, Fontelis, Rubigan, and Rally are highly effective against many tree fruit diseases.

Is coffee grounds good for citrus trees? ›

Ground coffee can be beneficial for citrus trees as it improves soil structure over time. Also, it contains important plant nutrients such as nitrogen, potassium, phosphorus, copper and magnesium to make it grow healthy and strong. Finally, it adds to the acidity of the soil, which citrus trees like.

Why are the leaves on my citrus tree turning yellow? ›

Very often the yellow leaves or chlorosis on a citrus tree is caused by over watering or a nutrient deficiency. Citrus need regular water especially in the warm months but over watering can leach nutrients from the soil and cause root rot. If the roots are damaged they can't take up the nutrients the plant needs.

Can you spray soapy water on citrus trees? ›

Solving Insect Problems on Citrus - YouTube

What is the best pesticide for orange trees? ›

One of the best pesticides for controlling citrus tree pests, including many types of scale and mites, is horticultural oil, which works by suffocating pests. Because it must make contact with insects to be effective, horticultural oil spray only works when pests are present and not as a preventative measure.

What is eating holes in my lemon tree leaves? ›

Just Bad Bugs

Those holes around the edges of leaves might be caused by cutting insects – slugs, Fuller rose beetles, leafrollers and Amobia caterpillars. Slugs and rose beetles are ground dwellers that eat holes in leaves.

When do you apply copper fungicide to citrus trees? ›

Timing. Liquid copper fungicide is a protectant, so it must be applied to the lemon tree before the disease presents itself. The ideal time to spray the lemon tree is in October, just prior to or after the first rain of the season. If the weather is particularly wet, repeat the application in January or February.

What does fungus look like on an orange tree? ›

The fungus appears as yellow, dark brown, or black lesions that initially occur on the underside of mature citrus leaves. As the fungus develops, the spots become visible on the leaf top. Citrus tree leaves affected by Greasy Spot will fall prematurely, which adversely affects tree health and yield.

How do I know if my orange tree is diseased? ›

Look for lesions of dead tissue on leaves, surrounded by yellow and dark brown lesions on fruit. Severe infection causes dieback, defoliation, and early fruit drop.

What time of year is citrus red mite most likely to cause problems? ›

Damage from citrus red mite in Southern California appears mostly in late summer or fall. In the San Joaquin Valley, mite damage is most prevalent in the spring. In the desert valleys, citrus red mite is an occasional problem in spring and a rare problem in the fall.

What causes leaf curl in citrus trees? ›

A. Citrus leaves can curl when temperatures are cold or in extreme heat, some insect infestations such as scale, mealy bug, mites or aphids will cause leaves to curl and also over-watering. Other times it is leaf curl disease.

What causes brown spots on citrus leaves? ›

Citrus Melanose

Infections of Melanose are caused when a substantial amount of the fungus is present on dead twigs or branches that are wet for an extended period of time, such as twenty-four hours or more, caused by either rain, or overhead watering. The fungus creates small brown spots on leaves.

How often can I spray my lemon tree with neem oil? ›

You will need to spray at either dusk or dawn to avoid harming beneficial insects. Apply the neem mix using a sprayer and try to be as thorough as possible. The spray should be reapplied every 7 to 14 days as both a treatment and preventative.

How do you spray a tree with neem oil? ›

Info Article When To Spray Neem Oil On Fruit Trees - YouTube

When Should I spray my fruit trees with neem oil? ›

Start applying neem oil in the spring as soon as the buds open to prevent pests from damaging the flowers. Other pests will target the fruits as well, so keep spraying the oil every two weeks until right before harvesting.

When do you apply copper fungicide to citrus trees? ›

Timing. Liquid copper fungicide is a protectant, so it must be applied to the lemon tree before the disease presents itself. The ideal time to spray the lemon tree is in October, just prior to or after the first rain of the season. If the weather is particularly wet, repeat the application in January or February.

Can you spray soapy water on citrus trees? ›

Solving Insect Problems on Citrus - YouTube

When should you spray citrus trees? ›

Spray 14 days after petal fall and then again in the middle of summer to capture the second generation. Use pheromone traps for pests such as codling moth and guava moth that burrow into fruit, when they are placed on the tree is critical for effective control.

How do you get rid of black spots on citrus? ›

Using hot water along with fungicides is the best treatment for citrus black spot at this time because the fungicides are already commercially used,” said Yan.

Can I spray neem oil on citrus trees? ›

Neem oil is safe for citrus trees as it is a natural pest repellent that won't cause any side effects if used correctly. You can apply neem oil on citrus trees as an insecticide, pesticide, or fungicide. Neem oil is a great natural pesticide for common citrus tree pests.

Can I spray copper fungicide on citrus trees? ›

Coppers are a cost-effective choice for citrus growers. The high surface area to mass ratio of very small copper particles in copper fungicide maximizes adhesion to crop plant surfaces, which increases efficacy and prevents the spread of disease, which could cost growers a lot more in the long run.

What can you not spray copper with? ›

However, it's best not to spray when bees are actively foraging on plants. Never apply copper fungicide on very hot days. Never mix copper fungicides with other chemicals. Never over-apply fungicides.

Can you spray vinegar on citrus trees? ›

Both citrus trees and avocado trees are tolerant of acidic and alkaline soils, but if your soil is prone to being too alkaline you can make it more acidic slowly by adding vinegar to the soil. The vinegar will not overly acidify your soil.

What do citrus mites look like? ›

The leaves of plants infested with citrus mites have an etched, silvery appearance or become spotted with yellow, necrotic regions. The fruit is obviously damaged, with areas of thick rind that grows dark brown or black. The pink citrus rust mite causes fruit to distort and stunt.

What can I spray on my lemon tree to keep bugs away? ›

Horticultural oil sprays are also effective in treating pests of lemon trees known as citrus rust mites. These are insects that affect lemons, for the mites attack immature fruit. They can also attack foliage and leaves in some cultivars. Repeated oil sprays will get rid of insects on lemon trees.

What can you spray on fruit trees to keep bugs away? ›

We typically recommend fruit tree sprays with a combination of insecticide and disease-control ingredients; including, but not limited to: Bonide Fruit Tree & Plant Guard; Bonide Fruit Tree Spray; Bonide Malathion Insect Control; Hi-Yield 55% Malathion; and Hi-Yield Lawn, Garden, Pet & Livestock Insect Control.

What's the best thing to spray fruit trees with? ›

Captan is generally considered a good choice for management of many fruit diseases. Sulfur is particularly good for powdery mildew, and is somewhat effective for scab, rust, and brown rot. Reliance on a mixture simplifies spraying fruit.

When do you prune and fertilize citrus trees? ›

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.

What causes black spots on citrus leaves? ›

Citrus black spot is caused by the fungus Phyllosticta citricarpa (formerly known as Guignardia citricarpa). The disease causes fruit blemishes and significant yield losses, especially on sweet oranges. Black spot can affect all commercial citrus species and cultivars commonly grown in Florida.

How do you treat citrus blight? ›

There is no cure for citrus blight. Aggressive pruning of an infected plant will temporarily halt the infection, but the measure is only temporary and the plant will eventually decline. Rates of citrus blight infection can be reduced by growing citrus-bearing trees on rootstocks that are tolerant to the disease.

How do you treat brown rot on citrus trees? ›

In addition to copper, other products effective against brown rot include the phosphonate and phenylamide fungicides. Phosphonates are applied as foliar and fruit or soil treatments, whereas phenylamides are applied as soil treatments for brown rot control.

Videos

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