Catunica adiposa

Initial signs of infestation appear as greasy, irregularly shaped spots on leaf blades. It is due to this specific appearance that the disease received its name — greasy or fatty (adiposa).

Over time, a necrotic zone forms in the center of the spots, acquiring a brown or dark brown hue. The boundaries of the affected areas are often bordered by a lighter, chlorotic halo.

Under high air humidity, the development of sporulation in the form of a thin grayish bloom can be observed on the underside of the leaves in the affected area. This is an important diagnostic feature confirming a fungal infection.

Deformation of plant organs is a frequent consequence of disease progression. Leaves begin to curl, and shoots slow their growth, leading to a general loss of the crop's marketability.

In the later stages, necrosis spreads to petioles and stems, leading to premature leaf drop and a significant decrease in the overall productivity of the crop.

The causal agent of this disease is the specialized micromycete Catunica adiposa. It is a highly specific parasite belonging to the group of fungal organisms that affect the tissues of higher plants.

The life cycle of the pathogen is closely linked to the weakening of the host plant's immunity. The fungus enters through micro-cracks or natural openings in the epidermis, subsequently initiating active development within the intercellular space.

The disease is classified as a focal necrosis of tissues. The pathogen produces specific enzymes that break down cell walls, causing a change in the consistency of the affected areas.

During its life cycle, Catunica adiposa forms specific conidial spores, which are easily dispersed by wind, raindrops, or during agricultural activities carried out in the field.

The survival of the pathogen during the winter period is ensured by the formation of dormant structures, such as sclerotia, which maintain viability in plant debris or the topsoil until the next season.

The main factor promoting the development of the infection is the prolonged persistence of high relative air humidity, exceeding 80 percent.

The temperature optimum for the development of Catunica adiposa mycelium is between 18–22 degrees Celsius. Under these conditions, the incubation period of the disease is shortened to a minimum, leading to epiphytotics.

Densely planted crops or plantings with poor natural aeration create an ideal microclimate for spore reproduction. Lack of ventilation triggers the development of primary disease outbreaks.

Excessive application of nitrogen fertilizers makes plant tissues looser and more vulnerable to pathogen invasion. Over-fertilized plants lose the ability to effectively resist fungal penetration.

The presence of water droplets on the leaf surface after rain or heavy irrigation is a critical moment, necessary for spore germination and the subsequent infection of healthy tissues.

The disease causes serious economic damage due to a significant reduction in yield. Due to the disruption of photosynthesis, plants are unable to accumulate a sufficient amount of nutrients.

Products obtained from affected areas lose their quality indicators: fruit shelf life decreases, and taste and appearance deteriorate, making the produce unsuitable for sale.

In the case of massive infestation, the total death of individual plants is possible, leading to sparse crops and, consequently, inefficient use of agricultural land.

The long-term persistence of the pathogen in the soil limits crop rotation options. Plots that have been heavily infected require a multi-year break before susceptible crops can be planted again.

Damaged tissues become entry points for secondary infections, particularly bacterioses, which in combination with the primary pathogen can lead to rapid rot of the entire plant organism.

Prevention begins with following correct crop rotation practices. It is unacceptable to return susceptible crops to the same plot earlier than 3–4 years after outbreaks have been detected.

The use of resistant cultivars and hybrids is the most effective way to contain the spread of the disease on an industrial scale.

Thorough cleaning and subsequent destruction of all plant debris in the autumn allows for a radical reduction in the infection reservoir in the field, preventing the pathogen from overwintering.

The application of systemic fungicides in the initial phase of symptom development helps stop the spread of the fungus. Treatments should be carried out strictly in accordance with the regulations for the use of the preparations.

• Thinning of dense crops to improve ventilation
• Timely application of potassium-phosphorus fertilizers
• Monitoring humidity levels in greenhouses
• Disinfection of garden tools after work