plant disease classification
The best and most widely used classification of plant diseases is based on the causal agent, such as a noninfectious agent or an infectious agent (i.e., a virus, viroid, mycoplasma, bacterium, fungus, nematode, or parasitic flowering plant).
STRATEGIES TO MANAGE DISEASES:
Tactics for the Reduction of Initial Inoculum
Tactics for the Reduction of the Infection Rate
Tactics for the Reduction of the Duration of the Epidemic
Source: https://www.apsnet.org/edcenter/disimpactmngmnt/topc/EpidemiologyTemporal/Pages/ManagementStrategies.aspx
- Avoidance—reduce the level of disease by selecting a season or a site where the amount of inoculum is low or where the environment is unfavorable for infection
- Exclusion—reduce the amount of initial inoculum introduced from outside sources
- Eradication—reduce the production of initial inoculum by destroying or inactivating the sources of initial inoculum (sanitation, removal of reservoirs of inoculum, removal of alternate hosts, etc.)
- Protection—reduce the level of initial infection by means of a toxicant or other barrier to infection
- Resistance—use cultivars that are resistant to infection, particularly the initial infection
- Therapy—use thermotherapy, chemotherapy and/or meristem culture to produce certified seed or vegetative planting stock
Tactics for the Reduction of the Infection Rate
- Avoidance—reduce the rate of production of inoculum, the rate of infection, or the rate of development of the pathogen by selecting a season or a site where the environment is not favorable
- Exclusion—reduce the introduction of inoculum from external sources during the course of the epidemic
- Eradication—reduce the rate of inoculum production during the course of the epidemic by destroying or inactivating the sources of inoculum (roguing)
- Protection—reduce the rate of infection by means of a toxicant or some other barrier to infection
- Resistance—plant cultivars that can reduce the rate of inoculum production, the rate of infection, or the rate of pathogen development
- Therapy—cure the plants that are already infected or reduce their production of inoculum
Tactics for the Reduction of the Duration of the Epidemic
- Avoidance—plant early maturing cultivars or plant at a time that favors rapid maturation of the crop
- Exclusion—delay the introduction of inoculum from external sources by means of plant quarantine
Source: https://www.apsnet.org/edcenter/disimpactmngmnt/topc/EpidemiologyTemporal/Pages/ManagementStrategies.aspx
DISEASES CAUSED BY NON-INFECTIOUS AGENTS
Many diseases and injuries caused by non-infectious agents result in heavy loss but are difficult to check or eliminate because they frequently reflect ecological factors beyond human control. Symptoms may appear several weeks or months after an environmental disturbance.
Noninfectious diseases, which sometimes arise very suddenly, are caused by the excess, deficiency, nonavailability, or improper balance of:
S/N |
DISEASE / PEST MANAGEMENT DESCRIPTION |
STRATEGY |
ACTION STEPS |
LINK |
1. |
Light |
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2. |
Air circulation |
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3. |
Relative humidity |
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4. |
Essential soil nutrients |
Use of organic foliar spray formula every 7-10 days. Integrate with animal urea. Formula: 100 ml vinegar 100 g brown sugar 30L water Use of ground cover (lawn / fodder crops) & no-till. |
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5. |
Soil-moisture-oxygen relations |
Use of ground cover and no-till. |
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6. |
Soil acidity |
Building swales and keylines to restore water table levels in the sand. |
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7. |
Soil alkinity |
Building swales and keylines to restore water table levels in the sand. |
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8. |
High Temperature |
Use of shade nets |
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9. |
Low Temperature |
Use of shade nets |
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10. |
Soil compaction |
Use of ground cover and no-till. Add lant composts regularly. |
DISEASES CAUSED BY INFECTIOUS AGENTS
Infectious disease cannot develop if any one of the following three basic conditions is lacking: (1) the proper environment, the most important environmental factors being the amount and frequency of rains or heavy dews, the relative humidity, and the air and soil temperatures, (2) the presence of a virulent pathogen, and (3) a susceptible host.
Plants are subject to infection by thousands of species from very diverse groups of organisms. Most are microscopic (is not visible to the naked eye), but a few are macroscopic. The infectious agents, as previously mentioned, are called pathogens (or agents of diseases) and can be grouped as follows:
S/N |
DISEASE / PEST MANAGEMENT DESCRIPTION |
SYMPTOMS |
STRATEGY |
ACTION STEPS |
LINK |
1. |
Viruses and viroids |
Symptoms. Because viruses are microscopic, the presence of a virus is only noticed if it produces recognizable symptoms in the organism it is infecting. In plants these symptoms include mosaic patterns, flower-break, deformed growth, chlorosis or yellowing, stunting and leaf distortion, ringspots, and vein clearing. These symptoms are the result of complex molecular interactions between the virus and the plant. In response to a plant's defense mechanisms, viruses can also trigger a counterattack, such as destroying the plant's defense proteins. Cultivated plants are often more susceptible to disease than wild plants because they are grown in close proximity to other plants of the same species or variety |
Practice crop rotation. |
Value |
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2. |
Bacteria |
Symptoms of bacterial infection in plants are much like the symptoms in fungal plant disease. They include leaf spots, blights, wilts, scabs, cankers and soft rots of roots, storage organs and fruit, and overgrowth. |
Protection |
Use of ground cover to regulate soil temperature. No till to retain beneficial insects and micro-organisms. Add plant composts that naturally introduces beneficial microorganisms that fight off disease-causing bacteria. |
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3. |
Fungi |
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Protection |
Use the formula by foliar spay on mildew formation. Apply every 7-10 days up to three times. Formula: 1 tbsp laundry detergent 1 tbsp salt 1 tbsp baking soda 30L water |
Natural pest control that works on aphids and powdery mildew: https://www.facebook.com/share/r/u6ShYZ7XHakfQ8dT/www.facebook.com/share/r/u6ShYZ7XHakfQ8dT/ |
4. |
Nematodes |
Infested potato plants may show varying degrees of stunting, yellowing of leaves and a tendency to wilt under moisture stress. Roots have swellings or galls, and beads or knots (hence the common name). Affected tubers have blisters or swellings. Symptoms are most severe when crops are grown on sandy soils and warm climates above 25°C |
Protection |
Plant growth-promoting rhizobacteria (PGPR) can control nematodes:
PGPR can also increase plant growth, nutrient uptake, and plant yield. Introduce rhizobacteria by adding plant composts to the soil. |
Value |
5. |
Parasitic Seed Plants |
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6. |
Aphids |
Aphids feeds on sap from the young stems and branches of its host plants often forming dense colonies on the host. Large numbers of aphids feeding can cause shoot dehydration, delayed plant regrowth and decrease in the mass of woody tissue. As a by-product of feeding, substantial amounts of honeydew are excreted. The sticky sugary substance attracts ants and wasps and can lead to the development of sooty mould. |
Avoidance Exclusion |
Avoid using animal manure. Avoid planting nitrate-loving plants (with thick leaves) when aphids thrive in season (spring / summer). Reduce the incidence of ant population in the area by keeping the surrounding lands moist. |
Add organic composite fertilizer from rice water that reduces nitrate content that also attracts beneficial insects: (2) Facebookk |
7. |
The tomato leaf miner, Tuta absoluta, can cause significant damage to tomato plants, including:
Tuta absoluta is a serious pest of tomato crops in South America, but it has spread to other parts of the world. The larvae can also damage terminal buds and flowers. See more below. |
Avoidance Protection |
Make the environment is unfavorable for infection. Brown or sand-coloured insects prefer dry environment. Keep the environment moist. In addition, a moist environment attract beneficial insects such as beetles and lacewing bugs that feed on their eggs and larve. |
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8. |
Ants |
Value |
Avoidance |
Make the environment is unfavorable for movement and multiplication of ants. Brown or sand-coloured insects prefer dry environment that keep their channels opens. Keep the environment moist. The water blocks of the channels effectively cutting off ants to the surface and milking and protecting aphids. |
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9. |
Termites |
Value |
Make the environment is unfavorable for movement and multiplication of termites. Brown or sand-coloured insects prefer dry environment that keep their channels opens. Keep the environment moist and roots of plants alive. The water blocks of the channels effectively cutting off termites to the roots. The water additionally keeps the roots of plants alive not giving termites the opportunity to eat the roots. |
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10. |
Moles, hares, mangoose |
Avoidance |
Make the environment is unfavorable for movement and multiplication of the animals. Brown or sand-coloured insects prefer dry environment that keep their channels opens. Keep the environment moist. The water blocks of the channels effectively cutting off their habitats. |
DBM caterpillars feed on plant foliage, stems, flower heads and pods (Figure 5). Older caterpillars eat many small holes in the leaves of the host plants, often leaving the leaf epidermis (outermost layer of cells) intact, creating a see-through 'window effect’
Most damage is caused by the caterpillars tunnelling into the heads of plants such as cabbage and brussels sprouts and feeding on floral buds, flowers and pods. They also cause contamination of produce by pupating inside broccoli florets and cauliflower curds.
Heavily damaged plants can appear stunted and in most cases will die. Extensive feeding on reproductive plant parts will significantly reduce yields.
Most damage is caused by the caterpillars tunnelling into the heads of plants such as cabbage and brussels sprouts and feeding on floral buds, flowers and pods. They also cause contamination of produce by pupating inside broccoli florets and cauliflower curds.
Heavily damaged plants can appear stunted and in most cases will die. Extensive feeding on reproductive plant parts will significantly reduce yields.
Army worms mostly feed on leaves, but under certain circumstances will feed on the seed stem, resulting in head loss. The change in feeding habit is caused by depletion of green leaf material or crowding. In the unusual event of extreme food depletion and crowding, they will 'march' out of crops and pastures in search of food, which gives them the name 'armyworm'.
Resources:
Companion Planting: https://www.mofga.org/resources/companion-planting/companion-planting/
Companion Planting: https://www.mofga.org/resources/companion-planting/companion-planting/