Leaf diseases: Diseases caused by fungus that attack the tomato leaves.
Leaf diseases in tomatoes will mainly attack the leaves, but as they develop, cracks may form in the foliage and create damage to the stems and fruits.
Leaf diseases affect the growth, the product and require early detection and treatment.
Early Blight: Alternaria Solani
The disease is characterized by mature leaves that have already been damaged by another factor.
Without treatment, the disease will progress to the stems and fruits.
Signs – Brown spots that appear dry around which there is a light area (yellow to white).
Septoria leaf spot: septoria lycopersici
Circular spots with dark-brown margins appear scattered over the leaves.Later, the spots enlarge and coalesce, and black dots appear in their centers.
Heavily infected leaves turn yellow, wither, and fall off.
Gray Leaf Spot: Stemphylium Botryosum
The disease belongs to the summer season and will appear when there is high heat and humidity conditions.
Signs – small brown spots that appear mainly on the top of the plant.
When it spreads, the spots will be extensive and conspicuous.
Immediate action needs to be taken to prevent significant damage to the plant and the plants next to it.
The treatment is the same as for the disease called early blight.
Late Blight: Phytophthora Infestans
The disease is especially common in areas with high humidity and temperatures which range from 53-77F (12-25 degrees Celsius).
The disease starts from the leaf area and progresses through the petioles to the stem.
Upon reaching the stem it causes mortality of the plant.
Signs – Abstract brown spots will appear on the leaves and a light to white green spot around them.
Sometimes a woolly covering can be identified at the bottom of the leaf that carries the fungal spores.
When it reaches the stems, brown, dark, long spots will appear on it.
Leaf Mold: Fulvia Fulva
The disease appears in high heat and humidity conditions.
The disease can appear by itself or in combination with gray leaf spot, which appears under the same climatic conditions.
Signs – light spots on the leaf while gray / brown mold spots may appear on the underside.
Powdery Mildew: Oidium Neolycopersici
The disease is the result of a fungus that lives on the leaf, without penetrating it.
Signs – the appearance of a gray / white felt layer at the top of the leaf.
Grey Mold: Botrytis Cinerea
A fungus that penetrates the plant through wounds, cuts or cracks, usually in the stem.
The mold will usually appear in the winter and at high humidity because the fungus needs water to penetrate the plant.
Signs – Gray mold, which usually begins in the stem area and without treatment will progress and lead to wilting of the plant.
Soil diseases: Diseases caused by soil fungus that attack the tomato roots.
Crown and Root Rot of Tomato: Fusarium Oxysporum sp. Radicis-lycopersici
Soil disease which is characterized in the area by low to moderate soil temperatures and it causes the plant to become dehydrated and “hollow”.
The disease can occur in weak plants that suffer from other diseases.
Signs – The plant looks “thirsty” and as the disease progresses the leaves lighten and wither.
A cross-section of the stem will indicate a dry, white core when the root area is found to be rotten, brown and dry.
Damping off: Pythium
The well-known plant disease is caused due to the fungus Pythium.
The disease mainly affects the roots of young seedlings.
It causes brown spots and rot on the roots and leads to their death.
The disease can spread rapidly and infect dozens of young seedlings within days, and usually originates in the soil in which the seedlings are located due to lack of sanitation, or in the water in which it is irrigated.
Bacterial diseases: Diseases caused by soil & aerial bacteria that attack stems & leaves.
Bacterial leaf spot
This disease is caused by four species of bacteria.
It occurs in tomato and pepper.
It causes leaf and fruit spots, which leads to defoliation, sun-scalded fruit, and yield loss.
leaf lesions are initially circular and water-soaked and surrounded by a faint yellow halo.
Disease development is favored by temperatures of 75 to 86 ℉ and high precipitation.
Bacterial Canker: Clavibacter Michiganesis
A disease that characterizes in the summer months, spread under humid conditions mainly by workers and tools.
Signs – brown spots between the arteries of the plant.
The leaves dry out and the plant withers.
There is no cure for this one, just a way to postpone it from spreading.
Pith Necrosis: Pseudomonas Corrugata
A disease that occurs on cold nights and under conditions of excess nitrogen.
The bacteria penetrate the plant through openings or wounds and progress through them to the rest of its parts.
Signs – brown necrotic spots on the stems near the point of penetration of the bacteria and softening of the stem.
A cut in the stem will reveal necrosis in the core of the stem, but not in the lead tubes.
The rot is soft and wet, and is sometimes accompanied by a bad odor.
The plant may appear in full turgor and not wither, but as the disease progresses it may gradually turn yellow and wither.
Viral diseases: Caused by viruses that are transmitted by insects between agricultural areas.
Tomato Spotted Wilt Virus: TSWV
The virus is transmitted by thrips and leads to growth retardation, damage to the fruits, leaves and eventually to the wilting of the plant.
Tomato Yellow Leaf Curl Virus: TYLCV
The virus is transmitted by the white fly and leads to damage to the plant which brightens, weakens and withers.
The fruits that began to develop before the infection are not affected by the virus.
Aphids appear all year round and especially in the transition seasons in temperate regions.
Unlike most aphids that feed on one species of plant, these feed on many plants.
The leaf aphids can be found on stems and in the lower part of young leaves.
They can reproduce easily.
Their average size ranges from 2-4 mm and they feed mainly on the mineral transport pipes of the plants, by sucking the liquids in the plant from the stems and weakening it.
Aphids can transmit viruses between plants, and are therefore considered particularly harmful and dangerous.
They are pear-shaped and can be green, yellow, black, red, brown or gray.
The wingless aphids have a soft body and thin, long legs.
The older leaf aphids have two pairs of wings, delicate and transparent, with the anterior pair larger than the posterior pair.
Signs that the plant is infected or damaged by aphids are:
The shape of the leaves becomes curly or distorted.
Black spots (a kind of black membrane) appear on the leaves, as a result of the formation of the “black soot” fungus, a sticky honeydew secreted by the aphids, while these feed on the sap in the plants.
Great invention of ants on the leaves, attracted to the same honeydew.
Uneven ripening of agricultural grain and vegetables.
A Pest which severely damages agricultural crops, especially in the hot months of August and September.
It is common in areas with hot and tropical climates and settles in the lower part of the leaves.
It feeds on hundreds of different varieties of plant species and crops such as tomatoes, cucumbers, eggplant, sweet potatoes, etc.
It has prickly mouth limbs that suck and feed on the leaf juice.
Sticky honeydew is then secreted which is fertile ground for the formation of black fungus on the leaves in the plant and as a result the plant is weakened.
It is considered one of the 100 most invasive species in field crops and is responsible for the spread of over 100 different viral diseases in plants.
The white fly is very tiny and difficult to spot.
Its body length is 1 mm to 2 mm, with a wingspan of 3 mm in white.
Its body color is light yellow and covered with a kind of white wax layer.
Mealybugs are harmful to the garden and are common mainly in hot places.
It is found on a wide variety of plants, shrubs, citrus trees and lawns.
A female can lay between 300 and 600 eggs per litter.
When laying the eggs, you can see a kind of compressed “cotton wool” with wax, which appears mainly in the lower part of the leaves.
The size of a mature Mealybug ranges from 2 mm to 7 mm.
It has a soft body and an oval shape with stripes.
On top of a mature Mealybug, there is a gray or white flour wax cover.
Spider mites are a real challenge for farmers.
These garden pests belong to the group of spiders, those that live in hot and dry climates.
These pests are very common especially in vegetable crops such as:
Tomato, Watermelon, Cucumber, Pepper, fruit trees and flowers.
The mites feed on the same plants and trees, while harming the plant by injuring its tissue on the underside of the leaf and sucking its liquid.
The mite is a particularly tiny insect that ranges in size from only 0.3-0.8 mm.
This pest form is like a spider with four pairs of legs.
There are yellow and red mites.
Signs of the pest:
yellowing of leaves, dryness, cessation of growth, damage to the amount of crop and in exceptional cases – death of the plants.
Pests of trees and plants can cause enormous economic damage to agricultural crops such as:
corn, pepper, strawberry, melon, onion, eggplant, beans, cucumber and tomato.
They are harmful by feeding on the plant by sucking the plant fluids.
As a result, the organs responsible for the process of photosynthesis in the plant are damaged and eventually the same plant can die.
In addition, thrips are known as pests that are carriers of various virus plant diseases.
The thrips are tiny insects 1-2 mm long.
Its body structure is very narrow.
Among the species, thrips can be found in different colors: yellow, green, brown, etc.
The thrips are mainly present in the upper parts of the plant and tend to hide in flowers.
In flowers, there are bright spots in silver and blackened margins with petals, necrosis and the color of flowers “broken”.
Furthermore, small blackheads accumulate which are basically thrips feces on the leaves.
In the fruit, damage can be noticed like discoloration of strawberry, distorted cucumber shape, safes in pepper and small holes formed in tomatoes.
There is a decrease in yield due to damage and shedding of embalmed flowers.
An insect that is especially harmful to citrus trees, but also to home gardens.
This pest tends to gnaw its way inside the leaf epidermal layer.
Because of this, there is a decrease in the efficiency of photosynthesis and as a result – there is damage to the growth of the plant.
The pest is active in the garden mainly in the transition seasons: autumn and spring, but also in the summer season.
Tomato leaf miner: Tuta absoluta
A moth, attacking only tomato and eggplant.
This pest tends to gnaw its way inside the leaf epidermal layer making mines in the leaves, destroying even the whole leaf.
It reproduces very fast.
Each female may lay up to about 300 eggs and 10 generations can develop each year.
The larva penetrates the stems and fruits.
In moth tomatoes may attack any part of the crop at any stage and may cause up to 100% destruction of the crop without proper treatment.
Caterpillars: Tomato hornworms and Cutworms
These are larvae of moths.
They feed on the leaves and stems of more than 80 plant species and cause major damage to economically important crops.
Snails and Slugs:
Slugs are actually snails without a shell.
Snails are mostly active during the winter season.
They are found in gardens, basements and courtyards.
These insects are especially harmful to plants, as they feed on plants in the process of decay and gardens with rich vegetation, vegetable crops and organic herbs.
Slugs tend to eat mostly at night or on rainy days, usually at temperatures between 5-22 degrees Celsius.
In addition, snails and slugs mainly like plants with soft tissues, succulent foliage, stems and fruits.
They can completely destroy young plants in a single night.
Identification characteristics of garden snails:
In general, most garden snails are similar, so it is difficult to tell the difference between them.
These are mollusks with a conch on their backs, a serrated head shape, they have one leg for movement and above them a viscous sac containing their internal organs, covered with a cloak.
Main characteristics of slugs:
The shellfish’s body contains a lot of water and they produce huge amounts of mucus.
A sign of slug inventions is a trail of sticky mucus they leave behind, which allows them to easily climb trees, plants and shrubs.
The slugs can carry on their body a parasite that is harmful to the vegetation, up to the tops of trees and branches.
The length of a slug can reach 15 cm!
The damage they cause:
There is nothing left of your seedlings except leaf ribs and stems, there are round holes in tomatoes, strawberries and other soft fruits and ragged holes in the edges and center of the leaves.
If you didn’t find what you were looking for, maybe the symptom is not a disease, but rather have an abiotic reason.
Check my post “Fruit problems that look like pests made, but are actually not” for plant disease symptoms that look like pests made, but are actually not.
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