The plants, in addition to being affected by multiple pests, can suffer from fungal diseases that can be devastating if not detected and treated in time. Among the various existing pathologies, those caused by fungi and other filamentous organisms – known as cryptogamic diseases – represent a real challenge for farmers, horticulturists, and gardeners of all skill levels. Although the term may sound unfamiliar to many, diseases such as anthracnose, powdery mildew, and downy mildew perfectly represent it, and without appropriate measures, they can seriously damage any harvest, garden, or green space.
In this article you will find a comprehensive explanation about What are cryptogamic diseases in plants?, how they originate, their life cycle, distinctive symptoms, prevention and control methods, as well as practical examples of the most common diseases. In addition, we integrate verified information on updated products and techniques To combat them, both natural and chemical, extensive information on new pathologies and expert advice to protect your orchard or garden.
What are cryptogamic diseases?
cryptogamic diseases They are those pathologies that affect plants and are caused by fungi, oomycetes, molds, and filamentous organisms of the parasitic type. The main causes include:
- True pathogenic fungi
- Oomycetes (pseudofungi, such as Phytophthora y Downy mildew)
- Some microscopic algae
When these agents attack animals, it is called mycosis, but when the victim is a plant, we speak of cryptogamic diseases. The term "cryptogamic" comes from the old classification of fungi as cryptogamous plants, as they develop from spores and do not have visible flowers or seeds.
These diseases represent approximately 90% of all plant phytopathologies., so knowing them and how to identify them is essential for anyone dedicated to plant care and cultivation. Although there are some viruses and bacteria capable of causing plant diseases, the incidence and diversity of fungi far exceeds that of other pathogens.
Factors that favor the development of cryptogamic diseases
The environment plays a crucial role in the emergence of cryptogamic diseases. High humidity, warm temperatures and leaf condensation These are ideal conditions for the growth of fungi and pseudofungi. Other factors that increase the risk include:
- Vegetation density which makes ventilation difficult
- Overwatering or poor drainage
- Wounds on plants caused by pruning, grafting or mechanical damage
- High level of organic matter in the soil
- Presence of infected plant remains
- Unbalanced fertilization, especially excess nitrogen
Evolution and life cycle of cryptogamic diseases
The development of a cryptogamic disease follows a series of clearly differentiated stages:
- Contamination: The fungal spores are carried by air, water, or insects to the plant surface. There, they take advantage of wounds, stomata, or lenticels to penetrate plant tissues. Occasionally, they can penetrate directly through the cuticle.
- Incubation: Once inside, the fungus germinates and branches, invading cells or intercellular spaces. This phase is usually asymptomatic and varies in duration, depending on the organism and environmental conditions.
- Symptom development and fruiting: The plant begins to show the first symptoms, such as spots, necrosis, wilting, discoloration, or the appearance of visible mycelium. At the same time, the fungus begins its reproductive cycle, forming new spores that will facilitate its spread to other plants.
- Dissemination: Mature spores are released, spreading the infection to other areas of the crop and restarting the cycle.
The consequences for affected plants can be serious: obstruction of the conducting vessels, tissue necrosis, reduced growth, and, in the worst cases, death of the plant. Therefore, it is vital act quickly at the first symptoms and employ effective prevention and control methods.
Main cryptogamic plant diseases
Below are the most common fungal diseases, their symptoms, and the most effective control methods. Familiarizing yourself with them will help optimize monitoring and treatment in orchards, gardens, and commercial crops.
Anthracnose
La anthracnose, also known as canker, is a very common disease in warm, humid climates. The fungi responsible usually belong to the genera Colletotrichum y Gloeosporium, although the species Coniothyrium fuckelii may also be involved in some cases.
- It can affect a wide range of plants, from fruit trees to vegetables and ornamental shrubs.
Main symptoms of anthracnose:
- Sunken spots watery appearance and variable colors in leaves, fruits and stems
- Necrosis in the veins of leaves, flowers, fruits and stems
- Death of affected tissues and subsequent wilting
The disease usually begins in wounds caused by pruning, grafting, or accidental damage. Therefore, it is essential to use clean tools and protect affected areas after handling.
Treatment and prevention:
- Removal and destruction of infected tissues
- Application of fungicides (preferably those with a copper base)
- Control of insect vectors and related parasites
- Use of resistant seeds and plants
- Natural treatments: horsetail slurry, nettle slurry, or preparations with garlic and bicarbonate
A preventive approach and rapid intervention at the first symptoms greatly minimize losses.
Botrytis (Gray Mold)
La botrytis, caused mainly by the fungus Botrytis cinerea (also know as Botryotinia fuckeliana), is one of the most feared cryptogamic diseases, especially in vine crops, strawberries, tomatoes, lettuce and numerous ornamental species.
This disease thrives in warm, humid environments, especially where there is poor air circulation and high crop densities.
Characteristic symptoms:
- Appearance of a grayish powder or mold on leaves, stems, flowers and fruits
- Leaves and fruits that turn brown or black before falling off
- Aborted flowers and poor overall growth
- Softness and rot in affected stems and tissues
Botrytis is especially harmful during the post-harvest phase, as it can develop during storage if humid conditions persist.
Control and prevention methods:
- Remove and destroy infected parts as soon as they are detected.
- Improve ventilation and spacing between plants
- Avoid sprinkler irrigation or wetting the foliage
- Apply appropriate fungicides, alternating active ingredients to prevent resistance.
- Disinfect pruning and harvesting tools
Mildew
The term mildew It encompasses different cryptogamic diseases caused by oomycetes, mainly Phytophthora, plasmopara y Downy mildewIt affects numerous crops, but is especially destructive in potatoes, tomatoes, grapes, lettuce, and spinach.
Typical symptoms of mildew:
- Greenish or yellow oily spots on the upper surface of the leaves
- Presence of whitish or grayish fluff on the underside
- Drying and premature fall of leaves
- Stem and fruit rot, especially in high humidity conditions
Mildew spreads rapidly in rainy, warm seasons, as spores germinate and penetrate plant tissue thanks to persistent moisture.
Control and recommended measures:
- Use resistant cultivars when available
- Ensure adequate ventilation and avoid high planting densities
- Apply preventive treatments with copper-based fungicides, alternating with biological products
- Remove crop residues and intervene only when environmental conditions are favorable for the fungus.
- Natural preparations: horsetail infusions against mildew
Among the diseases caused by mildew, the following stand out: plasmopara viticola (in vine), peronospora farinosa (spinach) and Phytophthora infestans (potato and tomato).
Powdery mildew
El powdery mildew, also known as ash or white disease, is one of the most recognizable cryptogamic diseases due to the whitish layer it forms on the leaves and stems. The main causative agent is Uncinula necator, although there are other species of the genus Erysiphe y Podosphaera depending on the crop.
Most common symptoms:
- Whitish or grayish ash-like coating on leaves and stems
- Appearance of dusty spots
- Yellowing and subsequent drying of the leaves
- Growth retardation and deformities
Powdery mildew is common in areas with high humidity, poor ventilation, and excess nitrogen, such as the Mediterranean region.
Treatment recommendations:
- Remove leaves and affected parts when the first symptoms are detected.
- Improve crop aeration by pruning and spacing
- Apply sulfur treatments in powder or suspension, preventing flowering
- Spray skimmed milk solutions (0,5 L per 8 L of water)
- Use horsetail infusions with fungicidal effects
- Dilute hydrogen peroxide (75 ml in 5 L of water)
Roya
La roya It is another cryptogamic disease caused by fungi of the genus puccinia and others, characterized by the appearance of yellow, orange, or brown pustules on the underside of leaves. It particularly affects legumes, wheat, and ornamental plants.
- The affected leaves fall prematurely, causing general weakness.
- Its development is favored by humidity and poor ventilation.
Prevention and treatment:
- Promote air movement in the crop
- Remove diseased leaves and plant debris
- Apply systemic fungicides or preparations with horsetail
Bold
La bold It is a secondary disease caused by the growth of saprophytic fungi in the honeydew secreted by insects such as aphids and whiteflies. It manifests as a black coating on leaves, fruits, and stems, hindering photosynthesis and weakening the plant.
- Controlling insect infestation is the most effective method of prevention.
Specific cryptogamic diseases in turf
Ornamental and sports turfgrass is particularly susceptible to several fungal diseases. The most common include:
- Fusarium: It causes yellow-brown spots and death of grasses, with white mycelium visible in humid conditions. The most affected species are: Poa sp.,.
- marasmius oreades (witch rings): produces dark green circles and the presence of fruiting bodies; reduces soil moisture retention.
- Sclerotinia homoecarpa (dollar spot): manifests as brown spots up to 6 cm in diameter and necrosis of the intermediate area of ​​the leaf, with mycelium that resembles white cobwebs.
Optimal irrigation, mowing, and fertilization management, along with the use of specific fungicides in case of attack, is key to controlling these diseases in lawns.
How to prevent and reduce the occurrence of cryptogamic diseases
Prevention is the most effective strategy against cryptogamic diseases. Below are recommended practices and proven effective products:
- Avoid excess moisture: Adjust watering to avoid saturating the substrate and prefer localized irrigation systems (drip) that do not wet the foliage.
- Improve ventilation: Avoid high densities and prune periodically to promote air circulation between plants.
- Crop rotation: Prevents the establishment of specific fungi in the soil.
- Disinfection of tools: Use alcohol or bleach after pruning diseased plants.
- Removal of plant debris: Remove fallen leaves, fruits and stems that can serve as a reservoir for fungi.
- Use of resistant cultivars whenever possible.
- Balanced fertilization: Avoid excess nitrogen, which promotes the development of more susceptible soft tissues.
Effective products and treatments to prevent and combat cryptogamic diseases
There are multiple control products and methods, both chemical and biological and natural, for the management of cryptogamic diseases:
- Copper-based fungicides: They are widely used and effective in preventing and treating mildew, anthracnose, and rust. Apply according to the manufacturer's instructions, preferably during periods of risk.
- Sulfur-based fungicides: Very useful in controlling powdery mildew.
- Sodium bicarbonate: Effective in preventive foliar applications for powdery mildew and downy mildew.
- Biofungicides: Products with Trichoderma harzianum and other antagonistic microorganisms, which limit the development of pathogenic fungi.
- SILISEC: A drying product that reduces ambient humidity and forms a barrier against infection. Apply at a rate of 500 g/100 L.
- CUPRIC CHELATED: Preventative fungicide that forms a protective barrier on the leaf surface. Recommended dosage: 50-80 g/100 L.
- Horsetail infusions: Powerful antifungal effect and useful in preventive treatments.
- Home treatments: Solutions of skimmed milk, garlic infusions, baking soda and hydrogen peroxide.
Good practices to minimize risk
- Perform frequent monitoring of plants, especially checking the underside of leaves and wet areas.
- Act immediately upon detecting the first symptoms, removing and disposing of infected parts.
- Avoid the indiscriminate use of pesticides, which can eliminate beneficial microorganisms from the soil.
- Consult with specialists to select the most appropriate treatment based on the crop and type of fungus
- Combining different methods to prevent the emergence of resistance in pathogenic fungi
Practical examples of control of cryptogamic diseases
To illustrate the application of this knowledge, several typical scenarios in orchards and gardens:
- In greenhouse tomatoes: Mildew can spread rapidly. Maintaining ventilation, removing lower leaves, and applying copper preventively during periods of high humidity are essential.
- In ornamental grass: Remove mowing debris, avoid nighttime watering, and use systemic fungicides if brown spots or white mycelium appear.
- In fruit trees affected by powdery mildew: Sprinkle with sulfur and remove infected leaves. Do not wet the foliage during peak humidity.
- In ornamental plants with botrytis: Reduce planting density, avoid wetting flowers, and remove diseased parts. For severe infestations, combine specific chemical fungicides with extra aeration and residue removal.
El early monitoring and immediate intervention are basic pillars in the control of fungal diseases. The integration of cultural methods, natural treatments, and specialized products guarantees the health and productivity of any crop. Prevention in plants can make the difference between a thriving plantation and a decimated crop.