Leaf curl is a common issue that affects chili plants and can be caused by different factors, including viral infections, fungal diseases, nutrient deficiencies, and environmental stress. Leaf curl in chili plants is defined by the curling, puckering, and twisting of leaves, which can impact the plant’s development and yield. Viral infections are among chili plants’ most prevalent causes of leaf curl. The tobacco mosaic virus and the cucumber mosaic virus are the two primary viruses that cause leaf curl in chili plants.
These viruses are typically spread via contaminated instruments, soil, or infected plant material. When the virus infects the plant, it can cause the leaves to curl, stunt development, and diminish yields. Fungal diseases such as powdery mildew and downy mildew are another source of leaf curl in chili plants. These fungi can affect plant leaves, causing them to curl, turn yellow, and ultimately die. Fungal diseases are typically transmitted by moisture and can be avoided by improving air movement, lowering humidity levels, and avoiding overhead watering.
Leaf Curl Management in Chilli/Peppers
Causes/Pathogen of Leaf Curl in Chilli
Begomoviruses, a group of plant viruses with a circular single-stranded DNA genome, cause the leaf curl disease in chili. These viruses are primarily persistently transmitted by whiteflies. Whiteflies are small, sap-sucking insects that are about 1.5 mm long. They have waxy white wings and a pale yellow body and are frequently found on the lower side of the leaves.
The Disease Cycle of Leaf Curl in Chilli
The disease cycle of leaf curl in chili starts when the whiteflies, the primary vectors of the virus, feed on an infected plant and acquire the virus. The virus then multiplies within the whitefly and is transmitted to a healthy plant when the whitefly feeds on it. The virus can also be transmitted from infected plant debris to healthy plants through contaminated tools, hands, or clothing.
Conditions Favorable for Leaf Curl Spread in the Field
- Leaf curl disease is caused by viruses spread by whiteflies and affects a wide range of plants, including chili. Several factors can impact the spread of the disease, including wind conditions, which can affect the distance that whiteflies can travel.
- Whiteflies are most common in the mid-to-late growing season and can survive in the environment through alternative hosts and weeds. Recent rainfall may also have aided the disease’s growth and spread.
- Chilli plants are most susceptible to infection in nurseries during the seedling and vegetative phases, particularly if infected transplants are used.
- Weeds can also raise your chances of getting infected. To control the spread of leaf curl disease, a variety of methods are used, including disease-free transplants, weed control, and the application of insecticides to control whiteflies.
Damage Symptoms of Leaf Curl
Leaf curl disease caused by the Chilli Leaf Curl Virus can cause significant damage to chili plants, affecting their growth and yield. One of the characteristic symptoms of the disease is the upward curling of leaf margins, along with the yellowing of veins and reduction of leaf size. The virus can also cause the swelling of leaf veins shortening of internodes and petioles. Older leaves may become leathery and brittle, and fruit formation in susceptible cultivars may be rudimentary and distorted.
If plants are infected early in the growing season, their growth may be stunted, resulting in a significant reduction in yield. Notably, the symptoms of leaf curl disease caused by the Chilli Leaf Curl Virus may be similar to those caused by the feeding damage of thrips and mites.