Q. How do I identify and cure plant disease?
A. correct diagnosis of plant disease requires a careful examination of the situation an systematic elimination of possibilities by following a few important steps.
1. Accurately identify the plant. Because infectious pathogens are mostly plant-specific, this information can quickly limit the number is suspected diseases.
2. Look for a pattern of abnormality. This can often provide key information regarding the cause of the problem. For example, if the affected plants are restricted to a walkway, road or fence, the disorder could be a result of wood preservatives, de-icing salts, or other harsh chemicals.
3. Carefully examine the land. Factors to observe include:
- history of the property
- number of species affected
- percentage of inured plants in the area
Poorly drained areas are ideal for the development of root rot induced by a variety of water molds. The history of the property and adjacent land may reveal many problems such as herbicides applied to agriculture lands or sanitary landfills whose gas can drift several hundred feet and damage plants.
The number of species affected may also help to distinguish between infectious pathogens that are more plant-specific as compared to chemical or environmental factors that affect many different species. Most living pathogens take a relatively long time to spread throughout an area, so if a large percentage of plants become diseased virtually overnight, a pathogen is probably not involved.
4. Examine the roots. Note their color: brown or black roots may signal problems. Brown roots often indicate dry soil conditions or the presence of toxic chemicals. Black roots usually reflect overly wet soil or the presence of root-rotting organisms.
5. Check the trunk and branches. Examine the trunk thoroughly for wounds, as they provide entrances for cankers and wood-rotting organisms. Such wounds may be caused by weather fire, lawnmowers, rodents, and a variety of other environmental and mechanical factors. you can avoid extensive decline by removing branch stubs and pruning out cankered limbs.
6. Note the position and appearance of affected leaves. Dead leaves at the top of the tree usually the result of environmental or mechanical root stress. Twisted or curled leaves may indicate viral infection, insect feeding, or exposure to herbicides. The size and color of the foliage may tell a great deal about the plants condition, so make mote of these and any other abnormalities.
Armed with information from this careful examination, you can now consult a plant disease reference or expert and make a diagnosis of the problem.