Potato Blight

Every kind of plant remains susceptible to diseases, and the potato plant is no exception. Potato blight is one of the many potato diseases which are known to create havoc in the production of this tuber. This disease occurs in two forms; early blight and late blight. The first one is caused by the organism Alternaria solani, and the other one, by Phytophthora infestans (also known as water mold). Among these two, the late blight is the one that is reputed to be the most notorious potato plant disease. It is infamous for having caused large-scale deaths in the 1840s; the incident was known as the Irish potato famine. Apart from this, it is also associated with the European and the Highland potato famines, in the same era. These diseases not only jeopardize potato production, but they also affect tomatoes and other members who belong to the Solanaceae family.

Potato Blight Symptoms

Early Blight

The common symptoms here include:

• Development of circular dark lesions (usually ½'' in diameter).
• The lower and older leaves are the starting point.
• Affected leaves wither off, die and fall off.
• Other symptoms are development of cankers on the stems, leaf blight, rotting of fruits and damping-off.

Late Blight

The symptoms that indicate a late potato blight infestation are:

• The leaves, stems and tubers are mostly affected by this disease. The leaves develop lesions at their tip or margins. These make them look as if they are soaked in water.
• With time, these lesions take on a black appearance, with a purplish shade. A yellow halo may be present in some cases.
• Lesions grow on the stem in an encircling manner, and are known to destroy the foliage that grow above the stem.
• The symptom of a foul odor often indicates that the infestation is a severe one.

Treatment

As soon as you notice the leaves getting affected, get rid of them. Best it is to burn the blight-affected leaves. Ensure that the plants are well earthed-up. This is to prevent the spores from invading the tubers. After you have gotten rid of the affected leaves, treat the plants with a fungicide. Inquire with you local garden center for the right kind of fungicide which can help in halting the spread of the blight. Usually, the fungicide needs to be diluted with water, and sprayed on the plants using a spray bottle. Read the instructions printed on the label to ensure that you are using the product in the right way.

If you notice that the infection is far too serious, then you may have to cut off the haulm, and burn it. It is beneficial to remember that, the earth provides protection to the tubers.

Treating potato blight can get a bit tedious, and so prevention is the best way out. Experts recommend the use of only seeds that have been certified to have been produced in places which are not prone to any plant diseases caused by fungi and others. Leave a gap of 3 years, before going for another potato plantation in the same spot. While harvesting, it is a good practice to keep the soil free of any remaining plants. This will ensure a clear and healthier soil, for the next plantation. Do not water the plants from the top, instead, water them at the base.