In tomato farming either organic or inorganic, the cost of controlling tomato diseases account highest. Proper early identification can help lower this cost and minimise losses. Unfortunately, most farmers cannot identify most of these tomato diseases correctly and end up incurring high costs in controlling them. In this article, we look at the causes, symptoms and the control of the most destructive tomato diseases.
Tomato late blight
What are the Symptoms of tomato late blight?
- Brown green spots appear on the leaf margin and leaf tops.
- Large parts of leaf turn brown completely
- White coverings on the underside of leaves
- Grey and brown wrinkled stains on fruits
- The fruits fresh is hardened and may decay
What is the Cause of Tomato late blight?
Tomato late blight is caused by a fungus that enters the plant via wounds. It spreads most in relative humidity of about 90% and temperature range of 18-26degree Celsius.
How to prevent Tomato late blight
- Avoid irrigating late in the day and irrigate plants at ground level
- Crop rotation
- Planting resilient varieties
- Early spraying of Redomil gold and score once per week in dry seasons and twice per week on rainy seasons for prevention.
Bacterial spot
What are the Symptoms of black spots?
Small yellow-green lesions appear on young leaves and even on fruits that eventually roughen, becoming brown and scabbed.
How do you control bacterial spots?
- Continuous crop scouting
- Avoid overhead irrigation and working in fields when foliage is wet.
- Avoid injuring plants during handling and planting
- Remove/prune and burn any seeding or plant part with leaf spots
- Clean tools and equipment’s
- Always plant clean seeds and seedlings
- Early spraying of Redomil gold and score once per week in dry seasons and twice per week on rainy seasons for prevention. In worst cases, fungurun can be sprayed to prevent the spread and damage.
What Causes black spots?
Prolonged leaf moisture and cool temperatures favour the spread of black spots. Black spots is the most devastating diseases as the diseases causing pathogens can survive in seeds, plant debris and specific weeds. Secondary infection can be caused by rain and overhead irrigation.
Once the crop is infected, it’s very hard to control and can cause total crop failure in days. Its misidentification has led to many farmers incurring high costs to control it.
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Tomato spotted wilt virus
What are the Symptoms of the tomato spotted wilt virus?
Initial symptoms are the brightening of young leaves with purple or brown spots on the leaves usually on the upper part of the plant.
Purple streaks and dark brown spots appear on stems and young leaves sometimes forming concentric rings. Infected plants bear immature tomatoes with moulted, light green rings and raised centres.
On ripe, fruits are red with striking brown rings accompanied by chlorotic spots with blotches that make the fruits unmarketable.
How to Control tomato spotted wilt virus
- Transplant from nurseries that have proper management of thrips
- Always avoid planting near crops affected by the virus
- Inspect and control thrips thoroughly through spraying insecticides like thunder.
- Remove infected plants and any plant debris and burn them
What Causes Tomato spotted wilt virus?
Transmitted by thrips as they acquire it by feeding on infected plants and have the ability to transmit it for the remainder of their lives
Powderly mildew
What are the Symptoms of Powderly Mildew?
Starts off as circular, Powderly white spots which can affect leaves, stems and sometimes fruits.it covers the upper part of the leaves but may grow on the undersides as well. This hinders photosynthesis causing the leaves to turn yellow, dry out. Some leaves might twist, break or become disfigured.
How to control Powderly mildew
- Ensure good spacing to allow good ventilation
- Regular monitoring to ease incidence of disease
- Do not touch healthy plants after touching infected plants
What Causes Powderly mildew?
The spores are transported by wind, water and insects from infected plant debris
Unlike most fungal diseases Powderly mildew can develop normally in dry conditions
Fusarium wilt
What are the Symptoms of fusarium wilt?
The plant show signs of wilting even at the juvenile stage with leaves turning yellow while mature plants show slight wilting on part of the plants. A dissection of the stem shows a strained brown or red stem.
How to control fusarium wilt
- Spray Redomil gold on the eve of transplanting
- Plant resistant varieties
- Handpick and remove affected plants
- Plough and burn plant debris after harvest
Which other tomato diseases are you finding hard to control and identify? Lets us know in the comments section below!
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