Damping-off of seedlings
How to Recognize the Symptoms of Chili Pepper Diseases?
Species from the Phytium genus: young plants at the point where the stem emerges from the soil have a watery zone where the plants break. Within 36-48 hours, damping-off symptoms can appear on the entire seedbed.
- Phytophthora capsici: this pathogen attacks the root and/or root neck of chili peppers. The root blackens or browns due to infection, and dark green ring-shaped zones form in the root neck area, causing the stem to narrow at that point.
- Rhizoctonia solani: this pathogen causes damping-off, browning, and rotting of young plants.
Generally, diseases caused by R. solani and Fusarium spp. occur in warmer and drier soil conditions, while infections caused by Phytium and Phytophthora are more common in cooler and moister soils.
Protection: sowing healthy seeds in sterile substrate and preventive treatment with fungicides.*
Why Sterile Substrate? The reason for using a sterile substrate is that the pathogens causing damping-off of seedlings spend part of their life cycle in the soil or substrate, and after optimal conditions (temperature, moisture), infection occurs.
Powdery Mildew
The causal agent of powdery mildew on peppers is the fungus Leveillula taurica. Infection occurs in summer months when the air temperature is >32 °C, and the relative humidity is low, 40-50%. This disease only appears on the leaves.
Symptoms of attack
Older leaves turn yellow, curl inward, and decay.
Under optimal conditions, a whitish coating resembling thick cobwebs appears on the lower part of the leaf (underside) – A TYPICAL symptom of powdery mildew.
Protection: removal of plant residues at the end of the season and weed control.
Why? Because the causal agent of powdery mildew on peppers overwinters on infected plants and weeds.
Application of sulfur-based fungicides.*
Root Neck Rot
Root neck rot is caused by the pseudofungus Phytophthora capsici. It can infect all parts of the plant, from roots, root necks, stems, leaves to fruits.
Symptoms of attack
Browning of roots and root necks, moist bark rot. Causes stem damping-off.
Leaves and branches develop dark red, moist, round spots.
Fruits develop water-soaked spots, white coating, and become wrinkled.
High temperatures and water are needed for infection, so the disease most commonly spreads within rows during irrigation or after heavy summer rains.
Protection: sowing in sterile substrate (because the causal agent overwinters in the soil/substrate), preventive treatment with fungicides.*
Gray Mold – Botrytis cinerea
Symptoms of attack
Moist (watery) rot on leaves and stems.
On fruits, olive-colored spots of various sizes appear, the tissue of infected fruits decays, and a dense gray coating forms.
Protection: Ventilation of the protected area if you grow peppers in a greenhouse or glasshouse, treatment with fungicides*.
Pepper Wilt
Pepper wilt is caused by the fungi Verticillium dahliae and V. albo-atrum. Both cause the same symptoms, with differences at the morphological level (time and method of overwintering).
Symptoms of attack
Reduced turgor (pressure) in the leaves, making the plant appear water-deprived.
Leaves yellow, wilt, and fall off.
Longitudinal cutting of the pepper stem reveals dark areas at the location of vascular bundles.
Protection: If such an infection occurs, do not grow peppers in that area of the garden for the next few years, and if grown in pots, be sure to sterilize them.
Bacterial Spot
The bacterial spot of peppers is caused by the bacterium Xanthomonas campestris pv. vesicatoria.
This disease most commonly occurs in July due to heavy rains. Disease development requires high air humidity and temperatures of 25-30 °C.
The bacterium is transmitted by infected seed and overwinters in infected plant debris. It enters the plant through hail wounds, strong winds, or tearing, initiating infection.
Symptoms of attack
Leaves develop round, watery dark green spots that eventually become necrotic (brown and dry) and are bordered by a light edge. Swelling is visible on the underside of the leaf where the spots occur.
On fruits, brown spots appear first, surrounded by corky tissue, and the tissue cracks – forming crusts.
The seeds in infected fruits turn black.
Protection: Planting healthy seeds, reducing air temperature and humidity – ventilating the protected area if growing peppers in a greenhouse or glasshouse. Avoid overhead watering. Fungicides* and copper-based fertilizers.
* These chili pepper diseases can also be chemically suppressed using fungicides – substances for prevention and/or control of plant diseases. Check the available products on the Ministry of Agriculture’s website of your country. Simply enter the name of the crop (pepper) and the harmful organism (e.g., powdery mildew) into the search engine. Or, for a simpler solution, visit your nearest agricultural pharmacy and ask for a product for the causal agent of the pepper plant disease.
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