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Fungicide refers to any poisonous agent used to kill or limit the growth of the fungus. Fungicides are used to manage parasitic fungi that cause economic harm to crops and decorative plants, as well as endangering the health of domestic animals and humans. The majority of fungicides used in agriculture and horticulture are administered as sprays or dust. Before germination, seed fungicides are administered as a protective layer. Systemic fungicides, also known as chemotherapeutics, are sprayed on plants, where they are disseminated throughout the tissue and work to eliminate or prevent disease. Pharmaceutical fungicides are often used as topical antifungal creams or as oral drugs in human and veterinary medicine.
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Key Terms: Fungicides, Pesticides, Fungus, Fertilizers, Germination, Weedicides, Agriculture, Parasites, Systematic Fungicides, Pharmaceutical Fungicides, Contact Fungicides, Xylem, Irrigation
What is Fungicide?
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Biochemical chemicals make up the majority of fungicides. It's used to get rid of fungus and insects in plants. Fungicides slow or stop the development of fungi. In agriculture, pests or insects can cause significant harm.
Fungicides applied to the leaf do not penetrate into plant tissue. It is sprayed from the leaf's upper surface to the lower, unaffected surface. Systemic fungicides are absorbed and reabsorbed by the plant's xylem vessels. Fungicides can spread to all areas of a plant. Some fungicides have a localized systemic effect. In addition, some of them are moving upward.
Fungicide
Fungicides can be broadly classified into three major categories- contact, translaminar and systemic. A detailed explanation of each type is provided below:
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Contact Fungicides
Contact fungicide, as the name implies, is not dispersed throughout all of the plant tissues and only protects the sections of the plants on which it is sprayed.
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Translaminar Fungicides
Translaminar fungicides disperse themselves from the top of the plant, where they are sprayed, to the bottom, where they are not sprayed.
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Systemic Fungicides
Because they disperse themselves to the plant's vascular tissues, systemic fungicides are the most effective. As a result, some fungicides are locally systemic, while others spread into plant tissues and others just remain on the surface where they are applied.
Read More: Difference Between Xylem And Phloem
Types of Fungicides
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Based on their characteristics, Fungicides are categorized in many ways of which some are listed down below:
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Preventive or Curative (Role in Protection)
Contacts serve both a preventative and a functional purpose. They affect the surface where they are sprayed or applied. The contacts' main disadvantage is that they must be administered repeatedly over some time. Because they are either washed away by rain or irrigation, or decay naturally owing to sunshine and other environmental reasons. They're commonly referred to as "residual" products since they stick to the leaves or other surfaces and leave a residue that can be seen for days. Systems, on the other hand, are regarded as both preventative and curative since they travel downward into the plant's tissues after being sprayed over the plant's upper surfaces. As a result, it has an effect on the pathogen following infection.
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Single Site or Multi-site (Breadth of Activity)
Single fungicides have a single point of action on a pathogen's metabolic pathway, a single essential enzyme, or a single protein that the fungus needs to flourish. They are not dangerous to organisms and are easily absorbed by plant tissues since their activities and levels of toxicity are highly specific. Because of a single mutation that occurs inside the pathogen, the effectiveness of this sort of fungicide decreases over time as the fungus gain more resistance to it.
Older fungicides were multi-site in nature, affecting a wide range of fungi in various plant sections. Scientists preferred to produce single-site fungicides due to the creation of new laws and regulations on the use of fungicides, as well as the stringency of the number of tests necessary to register a new fungicide.
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Narrow Spectrum or Broad-spectrum (Breadth of Activity)
Narrow spectrum fungicides are systemic fungicides with a single site of action that are effective against fungi that are closely related to their pathogens. Broad-spectrum fungicides, on the other hand, are frequently multi-sited and contact-based fungicides that are effective not only against closely related infections but also against pathogens that are unrelated to them. However, there are few single-sited broad-spectrum fungicides in nature.
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Organic and Inorganic Fungicides (Chemical Compositions)
The fungicides are classed as organic or inorganic fungicides based on their chemical makeup. Organic compounds are those with carbon atoms in their molecules, as defined in chemistry. Inorganic compounds, on the other hand, are those that do not include any carbon atoms. The majority of commonly used fungicides are inorganic chemicals, with sulphur having the largest proportion followed by copper. Inorganic fungicides like cadmium, mercury, and tin are used in certain fungicides. They are extremely poisonous.
Read More: Difference Between Pathogens and Parasites
Fungicide Chemicals
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Fungicides are the most efficient biocidal compounds for killing or preventing hazardous fungi or their molds from developing on plants, trees, or animal skin, such as rusts, mildews, or blights. Even though oomycetes are not called fungi, the method by which they affect plants is similar to that of fungi. Below is a list of some of the many types of fungicide compounds, along with some examples.
| Class of Fungicide Chemical | Examples of Fungicide Chemical |
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| Substituted Benzene | Chloroben, hexachlorobenzene, pentachloronitrobenzene, chlorothalonil |
| Thiocarbamates | Metam,ferbam, sodium, ziram |
| Ethylene Bis Dithiocarbamates | Mancozeb, maneb, nabam, zineb. |
| Thio Phthalimide Copper Compounds | Ethylmercury, methylmercury, phenylmercuric acetate |
| Miscellaneous Organic Compound | Benomyl, cycloheximide, triadimefon, metalaxyl, thiabendazole. |
The majority of these fungicides are now available in solid or liquid form. Sulphur, in various amounts, is the most common ingredient found in all chemical fungicides. Sulfur is found at 0.08 per cent in lesser amounts in most of these chemical fungicides, but it can reach 0.5 per cent in a few of the more effective fungicides. Sulfur concentrations in powder fungicides can reach 90 per cent, making them very hazardous.
Read More: Fungus Life Cycle
Benefits of Fungicide
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Plant diseases and biological degradation are typical occurrences that have a substantial economic impact owing to the loss of crops and decorative plant values. As a result, regulating the growth of fungus and bacteria, as well as managing illnesses, has become an important aspect of plantation and agricultural management. The following are the three most prevalent reasons for the use of fungicides:
- They are the most delicate during the establishment and growth of crops or plants. Fungicides are required to prevent the fungus from spreading and causing biological degradation of crops and plants in their early stages of development.
- For a beneficial economic consequence, it is critical to decreasing flaws to support healthy and plentiful agricultural and decorative plant development. Because of poor photosynthesis caused by rotting leaves, blemishes limit crop output. In addition, the quality of food crops decreases, and the economic worth of aesthetic plants decreases. To manage and minimize blemishes, fungicides are required.
- It's also necessary to guarantee that the crops, fruits, and vegetables that are preserved after harvest remain in good shape. The majority of the time, the fungus infects harvested crops as a result of climatic factors such as temperature that is conducive to fungal development or air humidity.
Benefits of Fungicide
Fungicide Resistance
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Fungicide refers to a circumstance in which a certain fungicide was successful in controlling a pathogen when employed on it, but after one or two applications on the same pathogen, it fails to control the population owing to the pathogen developing resistance to the fungicide used.
Several revolutionary processes are used to achieve this resistance. When compared to multi-sited fungicides, targeted pathogens are more likely to acquire resistance to single-site fungicides. Despite this, single-sited fungicides are preferable to multi-sited fungicides due to their lower toxicity and less harm to non-targeted species. If resistance develops as a result of the targeted pathogen's mutation of a single main gene, the pathogen's subpopulation will be either very sensitive or highly resistant to the fungicide.
In the case of agriculture or plantations, resistance is defined as the entire loss of the pesticide, since raising the chemical dosage or the frequency with which pesticides are distributed does not affect the population. The most important aspect of fungicide management is to extend the duration that the fungicide is effective. The major goal of fungicide resistance is to postpone the pathogen's growth rather than to manage the pathogen's resistant strain after it has been detected and targeted.
Read More: Economic Importance of Fungi
Things to Remember
- Fungicides are defined as those toxic substances that are used to kill or inhibit the growth of fungi in order to control parasite fungi as they damage agriculture resulting in damages to crops, yield and economic loss.
- Fungicides can be broadly classified into three major categories, namely, contact, translaminar and systemic.
- Food for human consumption has been found to have fungicide residue. This impact is noticed mostly as a result of post-harvest treatments.
- One of the first fungicides was the Bordeaux mixture, which was made up of hydrated lime, copper sulphate, and water.
- Fungicides are now often used to minimize mycotoxin contamination in wheat caused by the presence of Fusarium Head Blight.
- Some fungicides are harmful to people's health. Fungicides like vinclozolin, for example, have been outlawed due to their hazardous effects. Humans are also poisoned by this fungicide. It has the property of long-term exposure and, if eaten, is lethal.
Sample Questions
Ques. What is a fungicide used for? (3 Marks)
Ans. Fungicides are insecticides that kill or prevent fungus and their spores from growing. The fungicides are also useful in order to manage plant-damaging fungi such as rusts, mildews, and blights. Fungicides are often also used to keep mould and mildew at bay in other places.
Ques. Is bleach a fungicide? (3 Marks)
Ans. Bleach is usually thought to be a good fungicide (mold-killer). It could work in one situation: on hard, non-porous surfaces like a countertop or a shower stall. It may not be as effective on porous surfaces it may feed the mould and exacerbate the situation.
Ques. What is a natural fungicide for plants? (3 Marks)
Ans. Baking Soda Spray: Baking soda is a basic item in most homes. It aids in the prevention of illnesses or plant pathogens from infecting home garden plants. In a jar, combine 5 to 7 gm baking soda with 1 ml vegetable oil, then fill with 1000 ml or 1 lit pure or sterile water.
Ques. Are fungicides toxic to humans? (3 Marks)
Ans. Fungicide residues have been discovered on human food, primarily as a result of post-harvest treatments. Some fungicides, such as vinclozolin, are hazardous to human health and have been phased out of usage. Ziram is also a fungicide that is poisonous to people over time and can be lethal if consumed. Inhaling these pesticides' spray mist or dust might cause throat discomfort, sneezing, and coughing.
Ques. Is alcohol a fungicide? (3 Marks)
Ans. Ethanol is commonly used for surface disinfection and has been shown to have biocidal activity against bacteria, fungus, and viruses at concentrations ranging from 50% to 90%. In the current investigation, 70% of the antifungal agents were shown to be ineffective against common airborne fungal species.
Ques. How do you treat fungus on plants? (3 Marks)
Ans. Use just liquid soap, such as Ivory, rather than laundry detergent. Pour this mixture into a clean, empty spray bottle after stirring it around. Allow the plant to dry after spraying it fully, ensuring that both the upper and bottom leaves are covered. To manage the fungal condition, repeat the spray as needed.
Ques. Does Lysol prevent mold? (3 Marks)
Ans. Lysol tends to penetrate surfaces, which is vital for dealing with mould. However, the majority of Lysol users will also say that the mould grows back after some time. This is because Lysol has only been shown to keep mould and mildew at bay for up to a week.
Ques. What chemical kills mold spores? (3 Marks)
Ans. Mold is effectively killed by hydrogen peroxide on things such as clothes, flooring, bathroom fixtures, walls, and kitchen appliances. Now, fill up a spray container with hydrogen peroxide at a concentration of 3%. To saturate the mouldy surface with hydrogen peroxide, spray it fully.
Ques. What causes fungus in soil? (3 Marks)
Ans. Mold and other fungal illnesses feed on decomposing plant matter, thus an accumulation of dead leaves in the soil will promote mould growth. Remove the plant's dead parts before they build up near the base. To decrease yard trash, utilize fallen leaves as mulch outside.
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