These problems, diseases and pests are known to affect Tomato plants:
Tomatoes can afflicted by a large host of diseases and fungal infections. The good thing is that there are many tomato varieties that will have certain resistances to problems that might be issues for certain areas. Areas with high rain fall for example will have an increased risk for blights.
Another method to avoiding disease is to practise crop rotation. By not growing the same kind of plants in the same soil year after year this prevents diseases and fungi that cause disease from building up in the soil.
Good sanitation is also important for keeping your plants and garden space healthy year after year. If you suspect a plant of disease keep it from touching other healthy plants. Wash your hands and all tools well before using them on healthy plants if they’ve touched diseased plants.
Practising good weeding techniques is also important and weeds can often harbour disease for plant in the Solanum family but not show any outward signs themselves.
Below is a list of the some of the most common diseases and afflictions that can affect tomatoes. It’s important to get proper identification for your sick plant and what’s afflicting it if you suspect any of these. Bringing a small part of the plant to a local greenhouse will often give you the best result for identifying what’s wrong with your plant and getting the correct course of treatment.
Bacterial Speck : Caused mainly by a combination of cool (below 70F / 21C) and damp conditions.
Bacterial Spot : Common disease for tomatoes and peppers / capsicum caused by a bacterial species.
Bacterial Canker : Seed borne organism that attacks Tomato plants. Can survive for short periods in soil, and longer periods in leaf debris.
Verticillium Wilt : Caused by soil-borne fungi that attacks through the roots and grows upward into the plant, causing wilting of the plant due to water stress. Affects many species and can survive periods of cold weather.
Early Blight : Can be caused by periods of wet weather in the spring just after transplanting. Can be seed or soil borne
Tobacco Mosaic Virus : Tobacco Mosaic Virus (TMV) is carried by tobacco in cigarettes, and is mainly spread by infected hands touching plants or gardening equipment.
Tomato Yellow Leaf Curl Virus : TYLCV.
Blossom End Rot : A dark, indented, irregular-shaped patch that develops at the inferior aspect of the blossom or fruit, travelling out- and up-ward. Caused by an overall lack of calcium in the plant, which itself can be a symptom of multiple issues, including pH imbalance, over-fertilizing, under-watering, planting too soon (too cold). This is not a contagious 'disease' but rather a physiological disorder and lack of nutrients the fruit requires to produce healthy fruit. It cannot "spread" to adjacent plants, although if planted in similar conditions, other plants may suffer the same result.
Botrytis Rot : Botrytis rot or crown rot is a fungal disease that is very common in rainy weather.
Cucumber Mosaic Virus : Cucumber Mosaic Virus (CMV) was first found in Cucumbers, hence its name - however it is not limited to affecting only that plant. Mainly transmitted by Aphids and spread mechanically by humans. Can also be transmitted by seed. Can overwinter in roots of affected plants. Also known as: banana infectious, chlorosis virus, coleus mosaic virus cowpea banding mosaic virus, cowpea, ringspot virus, cucumber virus 1, lily ringspot virus, pea top necrosis virus, peanut yellow mosaic virus, southern celery mosaic virus, soybean stunt virus, spinach blight virus, tomato fern leaf virus, pea western ringspot virus
Cutworms : Cutworms are dull brown caterpillars that are normally they are found on or just below the soil surface or on lower parts of plants. They are smooth skinned and are most active at night.
Flea beetle : A generic term for a wide range of small leaf-eating beetles with powerful back legs that allow them to leap large distances (hence the comparison with fleas).
Earworms (corn) : Larval stage of a moth who lays it’s eggs on the silks. The caterpillars follow the silks and eat the corn.
Aphids : Also known as greenfly and blackfly, Aphids are a common sap-sucking garden pest.
Slugs : A snail without a shell. A mollusc with an elongated, soft body with a shiny appearance due to the slime coating.
White Fly : Small, white winged insects measuring between 1-2 mm (1/16th")
Thrips : Thrips are tiny white coloured flies that feed by burrowing into plant tissue - especially new buds and leaf growth.
Tomato Fruitworm : A caterpillar which causes damage to leaves by chewing through them and fruit by boring into young green fruits.