One of the greatest woes of gardeners is blight, a fungal infection classified into two categories: late and early. The first one is caused by the Phytophthora infestans, and the latter by the Alternaria solani. These organisms are also known to jeopardize other plants such as potatoes, and members of the Solanaceae family. Out of the two categories, late blight is known to be the most severe; it was responsible for causing the European, Irish, and Highland potato famines in the 1840s. It easily spreads from plant to plant, eventually infecting the entire colony.
One of the important steps in treating tomato blight is to identify the symptoms at the earliest. Most people fail to do so, and by the time they realize it, a significant damage is already caused. One must watch out for the lower leaves of the plant. The disease causes black or brown circles on them. These circles usually have a dark outer ring, with a light-shaded center. With time, as the infections spread, more and more leaves develop these circles. When left untreated, the leaves eventually turn yellow, and the entire plant is destroyed.
Disposal of Diseased Parts
This should be done at the earliest. So, remove the leaves, and burn them. This is to keep the infection from spreading to other parts of the plant, or the neighboring plants. Never leave the infected leaves to loiter on the ground. The organisms that cause blight, happen to stay in the ground. They would only get stronger with the help of the infected leaves.
Use of Fungicides
Spraying the plants with copper fungicide every 7-10 days, although does not cure this plant disease, but slows it down. In most cases, the product would have to be diluted with water, according to the manufacturer's instructions. Always consult your local garden store for a suitable fungicide for tomatoes.
This is one of the most effective, organic treatment methods to get rid of blight. It not only keeps the plants cool, but also prevents the blight-contaminated soil from reaching the lower leaves and stems of the plants. Gardeners recommend to keep a gap of at least 3 years, before planting the tomato plants in the same spot. This is due to the fact that there is a high probability of the soil remaining contaminated for these many years. Hence, it is better to go for a different location for the next few years.
Avoid Contact With The Soil
If staking is required to keep the plant from being close to the ground, then do it. You just have to get rid of the lower branches. This would keep the plants from coming in contact with the soil. Use drip watering method to prevent the soil from splashing onto them. Another point to keep in mind is not to water the plants late in the day, as this might cause them to retain too much moisture, eventually leading to infection.
Give Them Space
While planting, ensure that you are not making the place too crowded for them. Lack of air circulation invites the development of blight. Also, if the soil is well-cultivated and weed-free, you are lessening the chances of fungal growth.
Go For Variety
It is always better to go for multiple varieties of tomato plants, while you are starting the plantation. There are some varieties that are blight-resistant. These will, thus, help keep it away from the neighboring plants. Also, there won't be a total crop failure due to infection.
Preventing blight, in the first place, is better than treating it. Plants like tomatoes are always prone to such diseases. So, taking up measures at the beginning, would not only save time and money, but also cut back the chances of a total crop loss.