10 Plant Diseases Caused by Insect Pests
Most plant diseases are not a result of the plants themselves getting sick. They are caused by tiny, disease-carrying pests. Along with being a problem themselves, small insects like thrips can make a small issue into a plant health crisis by spreading bacteria, viruses, and fungi.
The first step toward gaining a healthy garden is stamping out threats. Without planting disease and without the insects that most disease plants, you can make sure your plants are healthy. This is one of the most common diseases of plants, and it is caused by insects.
Tomato Spotted Wilt Virus
If you are a gardener, you know the damage this virus can do. It is, unfortunately, a disease of many plants that are commercially grown or gardened. These include many common vegetables like potatoes, tomatoes, lettuce, and peppers. Ornamental plants are also included such as dahlias and impatiens. They are ALL spread by thrips, tiny disease-carrying insects that you can barely even see.
Symptoms: Stunted growth, necrotic spots, and dieback of stems occur due to infection from necrotic ring spots on fruit. Leaves are sometimes bronze, purple and then wilt.
Insect vector: Thrips become viruliferous as larvae feeding on an infected plant and continue to transmit the virus to healthy plants as adults.
Dutch Elm Disease
Dutch elm disease is a tragic epidemic of elm decline across North America and Europe. This vascular fungal disease results in the death of the plant by impeded water transport to the foliage.
Symptoms: "Flagging" is the first symptom, and it will result in one or more branches of the upper canopy wilting and their leaves turning brown or yellow. Eventually, the whole tree is affected and wilting becomes more severe.
Insect vector: Spike disease is mostly spread by elm bark beetles. These beetles tunnel in dead or declining elm wood and carry fungal spores. When they move to a healthy elm tree to eat, they introduce the fungus into the tree's water conducting tissues.
Huanglongbing (Citrus Greening)
Huanglongbing, aka citrus greening, is one of the most destructive diseases of citrus crops worldwide. Citrus greening threatens the most common citrus crops, such as oranges, lemons, and grapefruits. This disease is bacterial and is currently incurable.
Symptoms: Infected trees produce worthless crops: improperly shaped, taste bitter, and never ripen. The leaves become blotched and the tree deteriorates over time, resulting in death.
Insect Vector: Spread through an infection of the tree, it is a winged insect. They are known as the Asian citrus psyllid and as they feed on the tree they insert the disease into the tree.
Bacterial Wilt
As a disease of over a hundred species of plants, bacterial wilt is especially problematic for members of the cucurbit family (cucumbers, melons, squash) and the nightshade family (tomatoes, eggplants, and potatoes). The causative bacteria, Erwinia tracheiphila, proliferates the most in the plant’s vascular tissue.
Symptoms: the most notable symptom is drastic and permanent wilting. This often starts with a single leaf or vine, the rest of the plant may appear to recover at night, but as the day heats up, it will wilt on and off until it dies completely.
Insect Vector: Cucumber beetles are the biggest carriers. They're able to hold the bacteria in their system and spread it through their feed and waste.
Mosaic Viruses
There are multiple viruses known to infect plants and are known as the mosaic viruses. They are not limited to tropical plants and flowers like petunias and roses and can infect TMV and CMV.
Symptoms: There are multiple symptoms as well. For example, the infected plant may be stunted and have reduced fruit yield to be produced.
Insect Vector: Each plant that gets infected gets visited by an aphid that has the virus, and it gets transferred to that plant.
Aster Yellows
This disease affects over three hundred species of plants in the garden, including flowers, vegetables, and herbs, like asters and marigolds, and of all types of carrots and celcipes. The garden flowers include popular garden flowers like coneflowers. It comes from a bacteria-like organism that resides as a microorganism in the phloem of a plant.
Symptoms: Infected plants have odd symptoms; they develop odd growths which look like green leaves, other leaves start to yellow, and the leaves of the plants start to grow strange yellow colors, and they start to stunted growth and leaves start to develop yellow and the odd coloration of leaves start to grow to odd yellow colors.
Insect vector: Leafhoppers are the ones who transmit this disease. They feed on the sap of the garden. Sick plants ingest the disease and then transmit the disease to healthy plants when they keep feeding.
Fire Blight
Fire blight is a very destructive disease that is of a bacterial nature, and it primarily affects the rose family which notably includes; apples, pears, crabapples and the quince. This disease makes it look like the plants have fire damage of some sort and this is due to the infected parts of the plants.
Symptoms: Infected plants droop and they wilt away to turn black, and the cankers of the plants ooze a watery, tan liquid. When branches of the plants are infected, they look like they are burned.
Insect vector: In addition to how rain and wind can help to spread this disease, there are some other important insects that help to spread this disease. These insects include bees, wasps and some types of flies. They carry and spread the disease to uninfected flowers and cause new infected areas to develop.
Pierce's disease
Pierce's disease is a significant bacterial disease that affects grapevines and is very dangerous as it has caused a lot of harm and destruction to large areas of grape farms. This disease is very dangerous and lethal to grapevines. This is because the tissues of the plants that are affected help to control the flow of water that is absorbed by the roots and is then distributed to other parts of the plants.
Symptoms: Grapevines that become infected develop leaves along the edges that become scorched and are yellow or red before drying out and falling off. The fruit can shrivel, and the vine dies, usually within one to five years.
Insect Vector: A type of sap-sucking insect called the sharpshooter spreads the disease. These insects are glassy-winged sharpshooters that feed on the infected plants' xylem and, as a result, pass the bacteria onto healthy vines.
Pine Wilt Disease
This disease is a lethal affliction of pine trees, especially the non-native Scots and Austrian pines. It is caused by a pinewood nematode, a microscopic, quickly-multiplying roundworm that lives in the tree’s resin canals.
Symptoms: An infected pine tree's needles turn grayish-green, and then yellow, and finally brown in a very short time period, which is usually a few weeks or a few months. The tree will quickly die of wilting.
Insect Vector: The infecting beetle is the pine sawyer. The beetle gets infested with nematodes, and when it eats the healthy, tender shoots of a pine, it causes the nematodes to enter the tree through the feeding wouds.
Plum Pox Virus (Sharka)
The Plum Pox Virus is a serious viral affliction that affects stone fruits like prunes, peaches, apricots, and cherries. Trees infected with the virus do not die, but the fruit portions are too damaged to be sold.
Symptoms: The fruit itself is the most damaged; fruit has a loss of color, or yellow rings/spots are on the fruit, and they become very deformed and lose all taste. The leaves on the tree also produce light yellow rings.
Insect Vector: The Plum Pox Virus is spread by tree to tree feeding by some feeding aphids.
Protect Your Garden with Healthy Plants
Preventing plant diseases often requires the use of strong and healthy plants that are better suited to take on pests. The most proactive and preventive way to do this is to make the right plant identification for the specific environment and select strong, healthy plants that are for that environment.
At TN Nursery, the right plant for the right environment is a priority and the website has a large variety to choose from. The selection is high quality. It can be ordered online to be sent healthy, right to your house.
FAQs
What plant diseases are caused by insects?
Plenty of diseases can be spread by insects, like bacterial wilt spread by cucumber beetles, Tomato Spotted Wilt Virus spread by thrips, and psyllids spread citrus greening. They are vectors, meaning they spread viruses from infected plants to healthy ones.
What is the hardest pest to get rid of?
All of these pests are bad, but maybe thrips and spider mites are the worst. They are so little, and no matter how many times we try to get rid of them, they seem to reproduce faster than we get rid of them. They have a ton of places to hide since they reproduce and live in crevices in the plants so they're hard to get rid of totally after just one treatment.
What are the 20 plant diseases?
There is an endless list of plant diseases, but here are 20 of them to name a few. Powdery mildew, Downy mildew, Rust, Black spot, Fire Blight, Bacterial wilt, Mosaic viruses, Dutch elm disease, Root rot, Verticillium wilt, Fusarium wilt, Anthracnose, Damping off, Clubroot, Crown gall, Aster yellows, Scab, Leaf curl, Canker, and Blight.
What are the five common insects that cause damage to plants?
Some common plant diseases are powdery mildew which is very common and is a type of fungus, black spot which affects roses and is also a fungus, root rot which happens when the soil is too wet and also happens from a fungus, blight which happens to tomatoes and potatoes and is very damaging, and rust which happens to many plants and is also a fungus.
What are the 5 plant diseases?
Five common plant diseases are; powdery mildew, a common type of fungus; root rot, which is caused by soggy soil and fungi; black spot, a fungus that attacks roses; blight, which severely affects tomatoes and potatoes and rust, another fungal problem that affects numerous plants.
What are the five harmful insects?
Five harmful garden insects are aphids because of their ability to spread a lot of viruses; squash vine borers which kill squash plants from the inside; Colorado potato beetles which defoliate whole potato crops; and thrips for also transmitting viruses like TSWV, and scale insects, for weakening and killing woody plants.
