Tomato is the favorite vegetable for most of the people. Even its called as love apple and it is growing in various parts of the world. However one who tries to grow tomato is also need to take care of certain pest`s like leaf minor, fruit borer and diseases like damping off, late blight, early blight, leaf spot, bacterial canker and viral diseases.
In this blog we are going to know about late blight in tomato.

Late blight, also called potato blight, disease potato and tomato plants that is caused by phytopthora infestans

 The disease occurs in humid regions with temperatures ranging between 4 and 29 °C (40 and 80 °F). Hot dry weather checks its spread. Potato or tomato plants that are infected may rot within two weeks.

LATE BLIGHT- SYMPTOMS

1.Sudden and severe yellowing, browning, spotting, withering, or dying of leaves, flowers, fruit, stems, or the entire plant.
2. Most blight is caused by bacterial or fungal  infestations, which usually attack the shoots and other young, rapidly growing tissues of a plant.

3. Leaves have large, dark brown blotches with a green gray edge; not confined by major leaf veins.

4. Infections progress through leaflets and petioles, resulting in large sections of dry brown foliage.Stem infections are firm and dark brown with a rounded edge.

5. Firm, dark brown, circular spots grow to cover large parts of fruits. Spots may become mushy as secondary bacteria invade. In high humidity, thin powdery white fungal growth appears on infected leaves, fruit and stems.

6. Fungal and bacterial blights are most apt to occur under cool moist conditions, and most economically important plants are susceptible to one or more blights, including tomato, potato, and apples, as well as many ornamental species.

 PREVENTIVE MEASURES – QUICK POINTS

1. Destruction of the infected plant parts
2. Use of disease-free seed or stock and resistant varieties;
3. Crop rotation; pruning and spacing of plants for better air circulation                                                                                                                      4.Controlling pests that carry the fungus from plant to plant          

5. Avoidance of overhead watering and working among wet plants; and, where needed, the application of fungicide or antibiotics.

CULTURAL CONTROL

Before planting:

• Check plants in the nursery for late blight infections before taking them to the field or container. Destroy diseased plants.
• If unsure of symptoms, spray plants with a fungicide before transplanting in the field.
• Do not plant tomatoes next to older plantings of either tomatoes or potatoes; otherwise spores will spread by wind or wind-blown rain. 
• Use spacing between plants that allows air movement through the planting so that foliage dries as quickly as possible after morning dews or rains. For the same reason, orientate plantings parallel to the direction of wind.
• If using your own seed and the crop which the seed was taken had late blight, dry the seed for 3 days at 22^oC.

During growth:

• Do not use overhead irrigation; otherwise, it will create conditions for spore production and infection.
• Remove a few branches from the lower part of the plants to allow better airflow at the base.
• Prune any diseased leaves from the bottom of the plants as they become infected.
• If practical, grow tomatoes intercropped with non-hosts, e.g., beans, maize, papaya, bele; this will increase the spacing between plants, and reduce the spread of spores.
• Stake the plants to keep the foliage off the ground; it will improve air movement around the plants.
• Remove self-grown tomatoes, potatoes and Solanum weeds (i.e., volunteer plants) as they may have late blight infections.

After harvest:

• Rotate crops. Do not plant successive crops of tomatoes on the same land /container.

RESISTANT VARIETIES
Late blight tolerant varieties are available, so check if they are available in your locality.

HOW YOU CAN CONTROL THROUGH PLANT MEDICINES??
OEGANIC MEASURES
1.NEEM OIL –Give a spray of neem oil dilute 20 ml in 1 ltr of water with pinch of salt. Repeat the spray once in a week.

2.BAKING SODA – Take 3 table spoon baking soda and dilute in 3 ltr of water and add 1 table spoon of dish wash soap powder. Mix all the ingredients in a sprayer and apply to leaves of affected. It is best to remove leaves that are seriously infested if possible. Treat every one or two weeks.

CHEMICAL CONTROL

Silicate containing fertilizers may increase the resistance to the fungus, especially in seedling stage

1.Spraying of Mandipropamid, Chlorothalonil, Fluazinam, and Mancozeb.
2.Spraying of XYLOZEB, Specially for container gardening or urban farming