Papulosis

The main sign of infection is the appearance of specific small formations on the surface of stems, leaves, or fruits, resembling papules or small bumps.

The color of these growths can vary from light beige to dark brown or black, depending on the maturity of the fungal structures and the plant species.

Chlorosis or necrotic spots are often observed around the affected areas, indicating a disruption of physiological processes in plant tissues.

As the disease progresses, the affected areas may crack, leading to the deformation of plant organs and premature leaf drop.

Under high humidity, a noticeable mycelial bloom often appears on the surface of the affected tissues, which helps distinguish papulosis from other types of leaf spots.

The causative agent of the disease is a fungus belonging to the Papulosaceae family. These are specialized pathogenic microorganisms characterized by the formation of specific structures—papules (sclerotia-like bodies) that ensure the fungus survives under adverse conditions.

The type of disease is classified as a mycosis affecting various parts of the plant. The pathogen is able to persist in the soil and on plant debris for a long time, waiting for favorable conditions to germinate and infect.

The pathogen's life cycle includes phases of active mycelial growth and the formation of resting structures. These structures are extremely resistant to temperature fluctuations and fungicide exposure, making control a complex task.

The fungus penetrates the host plant tissues mainly through mechanical injuries or natural openings (stomata). The spread of infection within tissues occurs through intercellular penetration of hyphae.

Studying the biology of Papulosaceae requires particular attention to their reproductive strategies. Sporulation is often tied to periods of high humidity, which ensures mass multiplication of the pathogen in agrocenoses.

High relative humidity (over 80–85%) promotes the development of papulosis, acting as a key factor for spore germination and the formation of new papules.

The optimal temperature range for the development of the pathogen is usually between +18°C and +25°C. Sudden temperature changes can trigger the fungus to exit its dormant phase.

The presence of water droplets on the plant surface is a critical condition for starting the infection cycle. Heavy dew and fog significantly accelerate the spread of the disease.

Dense, poorly ventilated plantings create a microclimate with high humidity levels, which is highly favorable for rapid infection of healthy neighboring plants.

Poor agricultural practices, particularly the lack of crop rotation and the accumulation of plant debris in fields, lead to an increase in the infectious background in the soil.

The harm from papulosis lies in a significant reduction of photosynthetic activity of the affected plants due to the destruction of chlorophyllous tissues.

The disease leads to a slowdown in crop growth and development, which ultimately affects the weight and quality of the marketable harvest.

With severe infection, fruits lose their marketability, making them unsuitable for long-term storage and sale on the fresh market.

The pathogen can provoke premature wilting and death of individual vegetative organs, which weakens the plant's overall immunity.

Economic damage consists not only of harvest loss but also of costs associated with additional fungicide treatments during the growing season.

The basis of control is the observance of crop rotation, which limits the accumulation of the infectious source in the soil and breaks the pathogen's life cycle.

Deep plowing of plant residues and the use of healthy, certified seed material free of fungal spores are considered important preventive measures.

Preventive treatments with systemic fungicides allow for curbing primary infection and protecting sensitive plant organs.

• Regular weeding to remove potential infection reservoirs.
• Optimization of plant density to improve aeration.
• Timely application of phosphorus-potassium fertilizers to strengthen cell walls.

When signs of the disease are detected, it is necessary to immediately remove the affected parts of the plants and dispose of them through burning to prevent the spread of spores.