Alternaria leaf spot is a fungal disease caused by Alternaria spp, which affects a wide range of plants, causing significant losses. Disease development is favoured by warm and moist weather conditions while wet and moist conditions are very important for proper germination of the spores.
Younger, older and nutrient deficient plants are more vulnerable to attack by this disease.
A wide range of plants are attacked by Alternaria leaf spot. These include the following;
Tomato, cabbage, crucifers, beans, potato, pepper, cucumber, ornamentals, among others.
The fungus is a saprobe, i.e., it survives on dead plant material. It produces spores that are spread by wind or rain to healthy plants, initiating infections.
The spores can overwinter on old plant debris and attach themselves to seeds, making Alternaria leaf spot quite hard to completely eliminate, especially if one replants the seeds.
Infection & Symptoms
Infection leads to the development of lesions on the surface of leaves, which appear as small dark circular spots with light brown centers surrounded by dark concentric rings. This spotting is most prevalent on lower and older leaves. However, new leaves can also be attacked. Lesion centers may fall out, giving the leaf spots a shot-hole appearance.
Heavily spotted leaves turn yellow, wilt, and fall due to lack of water.
Leaves suffer the most from these symptoms, but stems, flowers, and seed pods can also be affected.
Management & Control
Considering the losses attributed to infections with Alternaria leaf spot, it is of great importance to timely and effectively control and/or manage the disease. This can be achieved through several ways, which include;
This involves the use of fungicides. The following fungicides have both preventive and curative properties and are thus effective against Alternaria leaf spot.[vc_column width=”1/2″]
- ABSOLUTE 375SC 10ml/20l
- BRADLEY 500SC 10ml/20l
- CHARIOT 500SC 20ml/20l
- COLONIZER 440WP 50g/20l
- DOMAIN 250EC 10ml/20l
- DUCASSE 250EW 20ml/20l
- EXEMPO CURVE 250SC 15ml/20l
- IPRODE 500SC 10ml/20l
- JUPITER 125SC 15ml/20l
- MEGAPRODE LOCK 525WP 20g/20l
- MILLIONAIRE 690WDG 40g/20l
- MONUMENT 400EC 40ml/20l
- PROVIDENCE 400WP 50g/20l
- PYRAMID 700WP 50g/20l
- RIMETA GOLD 300SC 40ml/20l
- TOWER 720WP 50g/20l
- TRINITY GOLD 425WP 50g/20l
- Whenever spraying any fungicide, it is recommended to mix it with INTEGRA 3ml/20l, which helps in enhancing its efficacy.
- Timely application of the fungicide is very critical.
- Alternation of different fungicides within a crop season prevents the pathogen from gaining resistant over any of them.
- Use of resistant varieties
- Planting certified or disease free materials
- Crop rotation with non-host plants
- Maintenance of field hygiene
- Proper weed control