von: Eder Herbert May 29, 2024

Introduction to Alternaria and frequency therapy

Alternaria is a widespread genus of fungi found in various environments and can affect both plants and humans. These fungi are known for their ability to survive and thrive in a variety of conditions, making them a serious problem in agriculture and healthcare.

What is Alternaria?

Alternaria consists of over 300 different species that can be found in both soil and plant tissues, as well as in the air. They are particularly prevalent in temperate climates and can infect a wide range of plant species including tomatoes, potatoes, carrots and cereals.

Distribution and significance

Alternaria spores are mainly spread by wind and water, which facilitates their spread in agricultural areas. Once established, Alternaria can cause significant economic losses, as infected plants often reduce their yields or die completely.

Impact on humans

Alternaria can also be problematic for humans. The spores of these fungi can trigger allergies and aggravate respiratory diseases such as asthma.

People with a weakened immune system are particularly at risk of developing serious health problems from Alternaria.

Alternaria and the immune system

The ability of Alternaria to affect the human immune system is another worrying aspect.

Studies have shown that exposure to Alternaria spores can trigger immune responses that lead to inflammation and other health problems.

Alternaria in tumours

Another important aspect is the role of Alternaria in the development of tumours. Some studies suggest that the mycotoxins produced by Alternaria may be carcinogenic .

This makes Alternaria not only an agricultural, but also a significant health problem.

Overall, Alternaria is a complex and versatile fungus whose understanding is essential for the development of effective control strategies.

The life cycle of Alternaria: How it grows and spreads

The life cycle of Alternaria is complex and allows this fungus to survive and spread effectively in different environments. Understanding this cycle is critical to developing effective control measures.

Germination and growth

Alternaria spores, commonly found in the air, soil and on plant surfaces, germinate rapidly under favourable conditions. These conditions include high humidity and moderate temperatures often found in temperate climates. Germination begins with the absorption of water by the spores, followed by the formation of hyphae that penetrate the plant tissue.

Sporulation

After germination and initial growth, Alternaria begins to produce conidia, a type of asexual spore. These conidia are produced in large quantities on the surfaces of infected plants and contribute to the rapid spread of the fungus. Sporulation is promoted by high humidity and light, which is why Alternaria outbreaks often occur after periods of rain.

Spread

Alternaria is mainly spread by wind and water. Wind can transport the light conidia over long distances, while water droplets can transfer them to neighbouring plants. Agricultural activities such as irrigation and harvesting can also contribute to the spread.

Infection and overwintering

Once on a new host plant, the spores penetrate the plant tissue and cause infections that appear as dark spots and lesions. Alternaria can overwinter in the plant debris, providing a continuous source of new infections the following year. Overwintering often takes the form of long-lived spores or mycelia that persist in the soil or on plant debris.

Summary of the Alternaria life cycle

Germination: Spores absorb water and form hyphae.
Sporulation: Production of conidia on infected plants.
Spread: By wind, water and agricultural activities.
Infection and overwintering: Penetration of plant tissue and survival in plant debris. Understanding this life cycle is critical to developing strategies for control and management of Alternaria in agriculture and horticulture.

Common symptoms and identification of Alternaria in different plants

Identification of Alternaria in plants is crucial for early control and minimising damage. Alternaria manifests itself through a variety of symptoms that can vary depending on the plant species. Here are some of the most common signs that indicate Alternaria infection:

Tomatoes

In tomatoes, Alternaria often manifests as black spots or concentric rings on the leaves, stems and fruit. These spots enlarge over time and can lead to leaf drop, which weakens the plant. Fruits can also be affected and then show dark, sunken spots.

Potatoes

Potatoes affected by Alternaria typically show brown to black spots on the leaves. These spots often have a yellow halo and can grow rapidly, leading to significant leaf loss. The tubers themselves can also be affected, which appears in the form of dry, dark lesions.

Carrots

Carrots show brown to black spots on the leaves and stems when infected with Alternaria. These spots can spread and destroy the entire leaf structure, which impairs photosynthesis and inhibits the plant's growth. The roots can also be affected and turn dark brown to black in colour.

Cereals

Cereals such as wheat and barley often show small, brown spots on the leaves and ears. These spots can develop into larger lesions and weaken the plants, resulting in a lower yield. Infection of the ears is particularly problematic as it can significantly affect the quality and quantity of the grain.

Identification and diagnosis

Alternaria can be identified by visual inspection and laboratory-based methods . Visually, the characteristic spots and lesions are often sufficient to make an initial diagnosis. However, for more precise confirmation, laboratory analyses such as cultivation of the fungi on culture media or molecular techniques such as PCR can be used. Early detection and correct identification of Alternaria are crucial in order to take timely measures to combat it and thus prevent greater damage to .

Impact of Alternaria on agriculture and horticulture in Germany

The impact of Alternaria on agriculture and horticulture in Germany is considerable and affects a large number of crops. Due to the climatic conditions that prevail in many parts of Germany, Alternaria fungi find ideal growing conditions, which leads to regular outbreaks. ### Economic losses Alternaria causes considerable economic losses in agriculture every year. Plants such as potatoes, tomatoes and cereals are particularly susceptible. According to a study by the Julius Kühn- Institute, crop losses in potatoes can be up to 20% if no suitable control measures are taken. These losses not only affect farms, but also the entire food supply chain.

Reduction in the quality of the harvest

In addition to quantity, Alternaria also affects the quality of the harvest. Infected fruit and vegetables are often unsightly and show black spots, which significantly reduce their marketability. This leads to price reductions and increased sorting costs for farmers. Tomatoes and carrots are particularly affected, as they quickly show visible damage due to their delicate structure.

Effects on horticulture

Horticulture is not spared from Alternaria either. Ornamental plants and tree nurseries regularly report infections that weaken the plants and impair their aesthetic quality . This is particularly problematic for export goods, as infected plants often require strict quarantine measures.

Environmental impact of plant protection products

The control of Alternaria requires the use of plant protection products, which in turn can cause environmental problems. The frequent use of fungicides leads to pollution of soils and water sources. There is also a risk of resistance developing, which can jeopardise the long-term success of control strategies.

Exemplary region: North Rhine-Westphalia

One particularly affected region is North Rhine-Westphalia, where the cultivation of potatoes and cereals plays a major role. Observations here show that Alternaria is particularly aggressive during humid summer months and leads to significant crop losses.

Summary of the effects

Economic losses: Up to 20% crop loss in potatoes.
Reduced quality: Reduced marketability of tomatoes and carrots.
Environmental impact: Use of fungicides and possible development of resistance.
Regional examples: High impact in North Rhine-Westphalia. The diverse and far-reaching effects of Alternaria make it clear how important effective control and continuous research in this area are.

Effective strategies to combat and control Alternaria

The control of Alternaria requires a holistic approach that includes both preventive and curative measures. The aim is to minimise the spread of the fungus and maintain the health of the plants. Here are some of the most effective strategies to control Alternaria:

Crop rotation and cultivation practices
One of the most important preventative measures is crop rotation. By regularly rotating the types of crops grown, the accumulation of Alternaria in the soil can be reduced . It is advisable not to grow plants that are particularly susceptible to Alternaria in succession on the same field. In addition, diseased plant remains should be removed after harvest and destroyed to eliminate overwintering sources.
Using resistant varieties Choosing resistant or tolerant plant varieties is another effective way to control Alternaria. Many breeding programmes focus on developing varieties that are less susceptible to infection. The use of such varieties can reduce the need for chemical pesticides and increase the sustainability of agriculture.
Optimising irrigation Excessive irrigation can promote the spread of Alternaria, as high humidity creates ideal conditions for the fungus. It is important to optimise irrigation so that the plants receive sufficient water without the soil becoming too wet. Drip irrigation systems are often more effective than sprinklers as they keep the leaves dry and control soil moisture.
Use of fungicides Fungicides can play an important role in the control of Alternaria, but should be used with caution to avoid environmental pollution and the development of resistance to . It is advisable to apply fungicides based on weather forecasts and infection risks. Rotating the use of different classes of active ingredients can help to prevent the development of resistant fungal strains.
Biological control Biological control methods are becoming increasingly important. The use of antagonists such as Trichoderma spp., which can inhibit the growth of Alternaria, represents an environmentally friendly alternative to chemical fungicides. The use of plant extracts and essential oils is also being researched to develop natural pesticides .

Summary of strategies

Crop rotation and cultivation practices: Regular rotation of plant species and removal of diseased plant residues.
Resistant varieties: Use of less susceptible plant varieties.
Optimised irrigation: Avoid excessive moisture.
Fungicides: Use with caution and rotate application.
Biological control: use of antagonists and plant extracts. By combining these strategies, farmers and growers can effectively control the spread of Alternaria and ensure the long-term health of their plants.

Future research and developments in Alternaria studies

Alternaria research is a dynamic field that is continuously generating new knowledge and developments. Innovative approaches and advanced technologies are needed to efficiently tackle the challenges that this fungus poses to agriculture and health.

Genome research and molecular techniques

A major advance in Alternaria research is the sequencing of the genome of different Alternaria species. By understanding the genetic structure, scientists can specifically identify genes that are responsible for pathogenicity and resistance . Molecular techniques such as CRISPR-Cas9 make it possible to edit specific genes and thus develop new, resistant plant varieties.

Development of biopesticides

The search for environmentally friendly alternatives to chemical fungicides has led to the development of biopesticides. These are based on natural antagonists such as bacteria and fungi, which inhibit the growth of Alternaria. Research shows that microorganisms such as Trichoderma spp. and Bacillus subtilis are promising candidates for biological control.

Early detection and precision agriculture

Modern technologies such as drones and satellite images enable the early detection of Alternaria infestations. In combination with big data and machine learning, precise forecasts and customised control strategies can be developed. Sensors that monitor soil moisture and climate data in real time help to optimise irrigation and minimise the risk of infection.

International cooperation and knowledge exchange

The global dimension of the Alternaria problem requires close co-operation between research institutions worldwide. International conferences and publications promote the exchange of knowledge and accelerate progress. Initiatives such as the Global Initiative for Alternaria Research (GIAR) play a key role in coordinating and funding joint research projects.

Summary of future developments

Genome research: sequencing and genetic editing to develop resistant varieties.
Biopesticides: Use of natural antagonists for biological control.
Precision agriculture: use of drones, big data and sensors for early detection and control.
International cooperation: networking and knowledge exchange through global initiatives. These promising approaches and technologies will make the future control of Alternaria more efficient and sustainable, which will protect both agriculture and human health in the long term.

Sources:

https://de.wikipedia.org/wiki/Alternaria

https://www.mri.bund.de/de/institute/sicherheit-undqualitaet- bei-obst-und-gemuese/forschungsprojekte/alternaria-pilze/

https://www.agrar.basf.de/ de/AgrarWissen/AgrarWissen/Kartoffeln/Alternaria-Arten-bekaempfen/

https:// www.lfl.bayern.de/ips/blattfruechte/024100/index.php, https://de.wikipedia.org/wiki/ Alternaria_alternata

https://www.allergy.de/aerzte-erklaeren/artikel/allergie-gegen-densaisonalen- mould-alternaria-alternata-clinical-relevance-and-treatment-m

https:// www.syngenta.de/produkte/kartoffeln-alternaria

https://www.schimmelpilz-fachzentrum.de/ lexikon/alternaria-schimmelpilzgattung/

https://www.lgl.bayern.de/lebensmittel/chemie/ mould-poisons/alternaria_toxins/index.htm

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