How To Control Plant Diseases

HOW TO CONTROL PLANT DISEASES Elimination or eliminating pathogens If the pathogen is not present in an area, early prevention efforts can be carried out by plant quarantine and seed certification can help in this regard. Treatment can also prevent the initial introduction of pathogens into the area via contaminated equipment, machinery, plant parts. If a pathogen is already present in an area, efforts can be made to eliminate it or reduce the amount of inoculum present. Perhaps proper elimination is done with chemicals, physics and biology. Cultivation practices such as: crop rotation, sanitation and so on can be used to reduce pathogen populations and reduce disease intensity Prevents the host from pathogens Protective chemicals on plant surfaces can be used to reduce the incidence of disease. Likewise, using systemic chemicals can be used to protect plants from disease. But perhaps it is better to protect the host from the pathogen by planting resistant cultivars. Modify the environment In some places the possibility of modifying the environment is suitable for the development of pathogens. But normally it is difficult to control the disease in this way. But in some cases it can work. Examples of controlling Phytophthora collar rot in citrus caused byPhytophthora citrophthoracan make it throughimproving soil drainage. There are a variety of strategies suitable for controlling plant diseases. However, the most appropriate one can be recommended, especially in certain situations, by considering several things such as: control must be economically profitable, suitable to be implemented, the right choice and not problematic for the future. Disease Control by Physical and Chemical Methods 1. Physical Method Control of pathogens using this method can be done by heat treatment (sterilization and pasturization), cooling, fumigation, spore trapping and so on. Example: controlling leaf spot disease on cabbage caused by a fungusAlternaria brassicaeAndA. brassicicolacan be controlled by soaking the seeds in hot water at 50C for 18 minutes 2. Chemical method Controlling plant pathogens using chemicals can include fungicides to control fungi, bactericides to control bacteria, nematicides to control nematodes.Example: Fungicide Fungicides are chemicals capable of killing certain fungi and these compounds often inhibit fungal growth or suppress spore germination and function asfungistatic agents. Fungicides can be classified as follows: Protectivenamely being able to protect plants or plant parts against infection due to pathogens on the part of the plant where it is applied.Eradicatenamely applied after the pathogen is present or to control the disease after infection has occurred.Systemicnamely the applied compound is active after being absorbed and translocated in the plant.The ideal fungicide compound for marketing must meet the following requirements: 1. The chemical compound must be effective at a concentration that is not harmful to the plant structure or growth stage. 2. Not harmful to humans and animals and will not trigger allergic reactions. 3. Minimal long-term impact on plant and soil microflora. 4. The compound is stable and relatively persistent in harvest materials and plant products. 5. Slightly changes the pathogen towards chemical resistance. 6. Contains compounds that can be accurately and effectively applied to plants. 7. Physically and chemically compatible with other biocide formulations. 8. Able to be stored for long periods of time under normal climatic conditions without losing its potency. 9. Initial price and application fees should be lower than the proceeds saved. Some fungicides contain inorganic and organic compounds. Inorganic fungicides usually contain main compounds such as: copper, mercury, zinc, cadmium and sulfur. Meanwhile, organic fungicides generally contain compounds such as: organo-metallic compounds, organosulfur compounds (including carbamates), heterocyclic nitrogen compounds, guanidine compounds and other organic compounds. The way fungicides work against fungi is as follows: 1.Affects cell wall synthesis and cell division. Some fungicides can inhibit or prevent the fungal growth process in the formation of new cell walls which are needed for elongation of hyphal tips, branching and spore formation. 2.Affects membrane permeability Fungicides with high surface activity (surfactants) have been shown to change the proportion of fungal cell membranes. Membrane permeability abnormalities can result either from the entry of substances to reach fungitoxic levels or from a lack of essential cell nutrients. Modification of membrane proportions can also inhibit the production or secretion of extracellular enzymes by fungal pathogens. This will limit the ability to form colonies on host plant tissue. The conditions of some fungi such as Erysiphales (which causes powdery mildew disease) are hydrophobic. Fungicide substances containing lipophilic proportions (e.g. phenolic compounds, dinocap, etc.) are better able to cross the walls and membranes of the conidia of this fungus than other substances. 3.Affects enzymes Enzymes are characterized by the presence of reactive parts such as amino acid groups (-NH2), imono groups (-NH), carboxyl groups (-COOH), hydroxyl groups (-OH) and sulphydryl groups (SH) in their molecules. Some fungicides react with this group and inactivate the enzyme system in particular. This results in frequent blocking of essential biochemical pathways of the fungus. Some fungicides such as captan can inhibit non-specific enzymes. Meanwhile, other fungicides such as: maneb, thiram, sulfur and ziram tend to inactivate specific enzymes in the Kreb cycle. Systemic fungicides such as carboxin appear to specifically inhibit the succinic dehydrogenase enzyme. Fungicide Copper can stimulateExcessive activity of some enzymes produced in abnormal fungal metabolism. 4.Affects Chelation and precipitation A variety of cell materials including amino acids, organic acids and enzymes can act as chelating agents or stable forms of organic complexes with metal ions. Although these reactions can reduce the activity of some metallic fungicides they can also create some essential fungal metabolites that are unsuitable for physiological processes. Fungicides containing sulfur compounds can affect essential metal ions as insoluble sulfide. 5.Competitive substitution of fungal metabolites Some fungicides containing chemical compounds usually affect fungal cell metabolites. When this substance is replaced by another metabolic process, it will affect the physiological sequence so that it can kill the fungus. 6.Other effects of fungicides Some fungicides appear to affect protein synthesis, others including the systemic fungicide benzimidazole may inhibit nucleic acid synthesis.