Act Now to Get the Jump on Frogeye Leaf Spot of Pepper
Cercospora leaf spot of pepper, (aka, frogeye leaf spot) caused by the fungus Cercospora capsici, is found worldwide. It is most damaging in tropical and subtropical regions where warm, wet conditions prevail. Frogeye spot is more common in northern Florida during the summer. It is rare in the southern part of the state but does present itself some years.
Symptoms of frogeye spot may occur on leaves, stems, petioles, and fruit stalks. The leaf lesions are distinctive and permit recognition of the disease in the field. Spots are circular to oval with a light gray center and a reddish-brown margin. Spots later become tan with a dark ring and a yellowish halo around the ring, resulting in a “frog-eye” appearance.
The centers of lesions often dry up and drop out as they age. When numerous spots occur on the foliage, the leaves turn yellow and may drop. Defoliation is often serious, exposing fruits to sunscald. Spots also develop on stems and petioles but are typically oblong rather than circular. Fruit are not infected.
Under conditions of high humidity, the fungus may be observed growing in the middle of the spot. A microscope shows colorless, multi-celled, needle-like spore characteristic of Cercospora fungi in the center of the spots arising from small black fungal tissue.
Survival and Spread
The fungus survives in or on seed and as tiny black fungal tissue known as stromata in infected plant debris in the soil. Spores will survive in infected plant material for at least one season.
Foliar infection occurs by direct leaf penetration. The fungus spores require free water for germination and heavy dew for penetration of the host and infection to occur.
Splashing water, wind-driven rain, wind, implements, tools, workers, and leaf-to-leaf contact can all spread the fungus. It is not known whether the fungus will infect solanaceous weeds.
As with all pathogens, an integrated approach is important in controlling this disease. Growers should plant certified seed from disease-free areas. Hot water treatment of seed from infected plants can reduce disease transmission.
Carefully check transplants for symptoms of the disease and remove and destroy affected and neighboring plants that may be infected.
Proper plant spacing in the field is helpful to allow for good air circulation and to reduce extended periods of leaf wetness.
Deep incorporation of crop residues and rotating crops using a two-year rotation period will assist in reducing pathogen survival between seasons.
Varieties differ in their susceptibility to frogeye leaf spot.
Field plantings should be scouted carefully for the first incidence of the disease particularly after extended periods of leaf wetness and warm temperatures. If symptoms appear, apply a protectant fungicide as soon as possible.
Consult UF/IFAS recommendations for labeled fungicides for frogeye leaf spot control on pepper in Florida.