11 Citrus Tree Pests and Diseases That Can Destroy Your Grove (2024)

FAQs

What disease commonly affects citrus? ›

Botrytis rot develops during cool, moist conditions, most commonly at coastal growing areas. Alternaria rot and brown rot cause similar injury and are more common diseases of citrus than Botrytis rot.

Trees infected with citrus blight experience a general decline in health; this includes wilting, die-back, loss of foliage, and the production of smaller/discolored fruits. The infection is not uniform—individual sections of an affected plant will go into decline as opposed to a sudden, plant-wide die-off.

In the past two decades, Florida's citrus industry has been threatened with greening and another disease called citrus canker. Citrus canker can cause the leaves and fruit on citrus trees to drop prematurely and create unappealing lesions on the fruit.

Fruit Fly. This pest is now becoming increasingly common as far south as Victoria, but the main areas of concern are warmer, more humid regions of NSW and QLD. Fruit Fly will lay eggs in fruits as they ripen, so it is important to collect and dispose of all citrus fruit, including those that have fallen to the ground.

A plant disease that kills citrus trees has been found in California. The disease, called Huanglongbing or citrus greening disease, isn't harmful to humans, but it is fatal for citrus trees and has no cure. The disease is spread by a pest called the Asian citrus psyllid as it feeds on citrus tree leaves.

Citrus scab is caused by a fungus and it produces slightly raised, pink or brown scabs on fruit and leaves. As the infected areas progress, the scabs will change color to a dark grey, and often crack. The clear oval-shaped type of spores are spread by splashing rain and die when they become dry.

Dissolve about 1 tablespoon of Epsom salt to a half gallon of water. Apply to the soil around your tree. Repeat the process once more in a few weeks. If treating a planted, outdoor lemon tree, sprinkle the soil surrounding the lemon tree with Epsom salt.

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.

The adult Asian citrus psyllid is a small brownish-winged insect about the size of an aphid. Its body is 1/6 to 1/8 inch long with a pointed front end, red eyes, and short antennae. The wings are mottled brown around the outer edge except where a clear stripe breaks up the pattern at the back.

Adult female citrus red mites are oval, globular-shaped and characteristically red. These mites feed on leaves, fruit, and green twigs of all citrus varieties. Leaf infestations are typically higher than those on the fruit. Citrus red mite produces little or no webbing on the plant.

What does a citrus tree borer look like? ›

Citrus fruit borer caterpillars are orange to dark reddish-brown with a dark brown head. They are fast moving and will jump or twist when touched. If detected, report immediately to Biosecurity Queensland.

Greening citrus leaves

If your citrus tree has leaves that are a sickly yellow colour, a presenter on Gardening Australia recommends the use of washing soda to fix it. Simply measure out about 50 grams of washing soda per metre of tree height, and place in 3-4 shallow holes around the tree's drip line. Too easy.

Citrus leafminer (Phyllocnistis citrella) is the larva of a small moth originating from south-east Asia and is commonly seen in backyard citrus trees. The larva infests young foliage in early autumn, peaking in April or May and feeds within the leaves creating distinctive silvery tunnels or 'mines'.

Citrus greening, a bacterial disease, is spread by a tiny insect, called the Asian citrus psyllid. According to the U.S. Department of Agriculture, the disease has been present in Florida since 1998.

Spraying soapy water onto a leaf is only useful if used as a biodegradable wetting agent to maximize adhesion to the leaf surface, so foliar nutrients don't just roll off the leaves. Although the soapy spray will probably drown the offending bug, it won't fix all the issues the pest caused your tree.

Apply composted manure around the base of the tree – taking care not to let it touch the trunk – and water it deeply to help the nutrients soak in. Urea is another nitrogen-rich fertilizer that can help correct a deficiency. Conduct a soil test to ensure all other macro and micronutrients are sufficient.

Brown rot is a very destructive disease of all stone fruits. The brown rot fungus (Monilinia fructicola) causes blossom blight, fruit rot, twig blight, and branch canker. Brown rot of ripening fruit is very common, and it generally occurs as the fruit approaches maturity.

The causative agents are motile bacteria, Liberibacter spp. The disease is vectored and transmitted by the Asian citrus psyllid, Diaphorina citri, and the African citrus psyllid, Trioza erytreae, also known as the two-spotted citrus psyllid. It has also been shown to be graft-transmissible.

Answer: We recommend Bonide Citrus, Fruit, and Nut Orchard Spray. This will treat for both insects and disease using all natural ingredients.

Can you spray vinegar on citrus trees? ›

Ideally, you should be using vinegar to spray areas in and around the garden, not directly on your plants. Vinegar is also great for chasing fruit flies away from your fruit trees and plants.

Baking soda on plants causes no apparent harm and may help prevent the bloom of fungal spores in some cases. It is most effective on fruits and vegetables off the vine or stem, but regular applications during the spring can minimize diseases such as powdery mildew and other foliar diseases.

Adding Epsom salt is a simple way to increase the health of their blooms, and is something that you can include easily as a part of a normal routine. For potted plants, simply dissolve two tablespoons of Epsom salt per gallon of water, and substitute this solution for normal watering once a month.

In newly infected lemon trees, HLB first causes leaves to take on a mottled appearance. Leaves will have blotches of yellow. Once a lemon tree becomes chronically infected, the leaves will show blotchy brown and yellow spots on one side but not the other.

Are your citrus tree leaves a pale green, white, or yellow colour with strange-looking green veins? Sometimes, this means your soil is too alkaline, so your tree roots can't absorb iron. Visit your local garden centre and pick up iron chelates. These work as a liquid feed for the foliage.

A tree with yellow or cupped leaves, or leaves that don't look perky AFTER watering can indicate excessive watering and soggy roots. Give your tree water less often. Citrus prefer infrequent, deep watering to frequent, shallow sprinklings.

The characteristic symptom of exocortis is the shelling of susceptible rootstocks. The viroid kills the bark, which dries, cracks, and may lift in thin strips. Droplets of gum often appear under the loose bark.

What do citrus aphids look like? ›

The three most common aphid species can be distinguished by color: spirea aphids are always bright green, black citrus aphids are shiny black, and the cotton aphid can range in color from yellow, to green, to dull black.

A symptom of Huanglongbing is yellow discoloration on leaves that is asymmetrical, meaning not the same on both sides of the leaf. Huanglongbing causes uneven yellowing in citrus tree leaves because nutrients are being restricted.

What do mold mites look like? They look like spiders but even smaller. They range from white to brown and can only be seen under a microscope or a special high-definition camera. They may even be mistaken for mold at first.

To the naked eye, thrips themselves look like tiny, white, cigar-shaped worms when they are in the larva stage. Once they become adults, they look more like tiny, long, slender black bugs. If you think you may have spotted one, but aren't sure, blow gently towards the bug. If it's a thrip, it will scurry away!

At first glance, many scale insects look like a small, circular bump that's part of the plant. Depending on the species, they vary in color from brown to cottony white and measure up to 1/4 inch long. Scale nymphs are known as crawlers and are similar in appearance.

Symptom of Damage :

Presence of brown coloured egg mass near the leaf tip. In vegetative stage larva enters the stem and feeds on the growing shoot and causes drying of the central shoot known as “dead heart”. In grown up plant whole ear heads become dried and yield chaffy grains called as “white ear”.

Citrus canker is a disease affecting Citrus species caused by the bacterium Xanthom*onas (X. axonopodis; X. campestris). Infection causes lesions on the leaves, stems, and fruit of citrus trees, including lime, oranges, and grapefruit.

Citrus greening disease symptoms vary widely but include new leaves that emerge small with yellow mottling or blotching, yellow shoots, enlarged and corky leaf veins, as well as fruits that are small with green ends and filled with small, dark, aborted seeds and bitter juice.

Chemical Control of Whiteflies, Leafminers, Mealybugs, & Aphids: Horticultural oil sprays will control whiteflies, mealybugs, and aphids, but not leafminers. On citrus trees, apply horticultural oil sprays when pests are present, and when temperatures are between 45 and 85 ºF.

How does the disease spread in a citrus grove? ›

This disease is easily spread by moving infected plants (including infected trees from nurseries) and by a small insect called the Asian Citrus Psyllid (ACP). Propagation or production of new trees using bud or budwood materials from infected trees is also a prime way to spread citrus greening.

Citrus leaves can curl when temperatures are cold or extremely hot, some insect infestations such as scale, mealy bug, mites or aphids will cause leaves to curl. Over-watering can also cause this. Other times it is leaf curl disease.