Tomato Diseases and Pests

Category: Vegetables post

Author: Garden

Disease. Phytophthorosis. Caused by potato blight (Phytophthora infestans (Mont.). De baryon). Brown spots appear on the leaves, stems, but most of them appear on the fruit itself turning it into mottled brown. Spots have blurred edges and hard consistency, may vary in their size. The fruit that is infected with phytophtorosis will also be brown on the inside. Spots on leaves are irregular, gray-brown and often with a lighter periphery.
To protect tomatoes from phytophtorosis you should avoid planting tomatoes near potatoes. Once the first symptoms of the disease appear on potatoes, tomatoes must be sprayed with fungicides too.
Leaf Blight of Tomato and Black Fruit Rot.
Disease is caused by early blight (Alternaria solani Sor.; Macrosporium solani (Eli. and Mart).At first small, brown concentrated spots appear on the lower leaves. Spots spread rapidly and converge with one another covering the most part of the leaf while it finally it withers. Fruits can be infected with early blight through the mechanical injury. The rotting part of a fruit collapses and becomes dry. Seeds can get infected from the fruit itself too. For the protection from disease plants should be sprayed with fungicides.
Septoria Leaf Spot of Tomato. The disease is caused by the tomato septoria (Septoria lycopersici Speg.). It usually infests tomatoes which are grown in the field, but occasionally the disease can spread among greenhouse tomatoes too. Signs of the disease: bright spots on the leaves, which cause the leaf to wither fast. To protect tomatoes from Septoria leaf spot you should use fungicides.

Brown Tomato Leaf Mould. The cause of the disease is the fungus Fulvia fulva (Cladosporium fulvum Cooke). Firstly, yellow blurry spots appear on greenhouse tomato’ leaves; then, the bottom half of the leaves where spots are located, starts to develop gray and brown mushroom coat on it. When the disease faces favorable conditions to spread (96% humidity and 22-25 ° C) the number of such spots increases a lot causing leaves to wilt.
During the vegetation greenhouses should be well ventilated so that the relative humidity in them would not exceed 70-75%. When first signs of the disease appear tomatoes should be sprayed with fungicides immediately, in such a way where
chemicals could enter the lower side of leaves.

Viral Diseases – Mosaic and Stripe. Mosaic is caused by the potato virus X (Solanum virus-1 (Orton) Smith). Infected leaves, especially the upper ones, often become mottled (areas of lighter and darker shade of green and yellow), sometimes even deformed – develop a curved edge, the surface of the leaf becomes uneven.
Stripe pathogen: the tobacco mosaic virus (Nicotiana virus 1 (Mayer) Smith), cucumber mosaic virus (Cucumis virus 1 (Doolitle) Smith), potato virus X (Solanum virus-1 (Orton) Smith). Not only leaves but also stems, leaf-stalks and fruit develop symptoms of it. When infected with stripe, leaf veins often darken. In some cases dark, necrotic and asymmetrical spots will appear on the leaf. Leaf-stalks and stems develop brown, linear streaks. Fruits can be spotted with brown stains too.
Stripe is considered to be one of the most dangerous viral diseases of all which infect the greenhouse tomato. For it may cause a total destruction of the harvest.
Viral pathogens spread with the seed. They are easily transmitted from one plant to another: while looking after tomatoes (by trimming and binding the tomato) and the insects. Pathogens winter in infected crop residues and weeds.
To avoid the tomato virus only healthy seed should be sown. It is advisable to spray tomatoes with skimmed milk, which is diluted with water in a 1: 10 first. Tomatoes should be sprayed three times: before re-planting them into bigger jars, before planting them into soil and 5 – 7 days after.
Pests. Potato Moth (Hydroecia micacea esp.). Its caterpillars sometimes damage the tomato plants in both greenhouses and fields. Ann average adult moth is usually stout: tank wings are brownish-purple with darker transverse lines, while rear wings are plain, yellow-grayish. Moths fly at night. Caterpillars tend to be 30 – 40 cm long, brownish in color with longitudinal red lines and black dots in rows. Have a reddish brown head, 8 pairs of legs. Caterpillars harm the tomato by gnawing paths on the inside of the stem. Affected plants wither and die. Attacks of caterpillar increase massively on June, when tomato plants are transplanted into fields. Pupal winter in soil. During the year 2 generations develop. Security measures: liming acidic soils, adding fertilizer to plants, blanching tomato seedlings. You should also heap the lower part of the stem with the soil, root out and destroy damaged plants immediately.