For a disease to develop, three conditions need to happen:
- There is a host plant susceptible to the disease.
- The pathogen which causes the disease is present.
- Environmental conditions are favorable to the development of the disease.
This is called the disease triangle. We may act on all three sides of it to keep our crops healthy.
Most diseases are able to affect only certain plant species, and quite often we can find varieties from the same species
which are genetically resistant to diseases. A lot of research is done to develop these resistant strains. There are normally alternatives for the most widespread diseases like Fusarium sp., nematodes, powdery mildew and others. When a new disease vector appears (often foreign virus introduced in local cultures) there is a race to bring to the market new seeds resistant to the infection. Check about varieties and disease resistances when choosing the seeds for your next culture.
When you suspect some disease is affecting your culture,check Cabi or PQR to find if it has appeared in your area before. If it hasn’t, the infection is probably not what you thought. You need to know what is attacking the crop and how it spreads (water, air, cutting tools, seeds …) to decide how to counter-attack to minimize the damage.
Avoiding expansion of known diseases is a concern for governments. When new or imported diseases appear in a certain area, they easily affect non-resistant plants, sometimes causing extensive damage and billionaire losses to the agriculture sector.
Sometimes you want to grow a certain variety which is not resistant to some diseases: the flavor or the productivity are important factors to take into account when choosing your seeds. Moreover, some very aggressive diseases like botrytis or powdery mildew are very difficult to stop and they attack a large number of different crops (they are known as “polyphagous”)
In these cases you need to be extra careful in controlling the environment. Learn and put into practice the best practices to avoid plant disease. As far as possible, avoid all the factors that help the development of the disease:
- High temperature.
- High relative humidity.
- Water droplets on the leaves.
- Injuries in the plants
- Weak plants
There is some simple advice to follow in order to have a healthy culture, but as I write I realize that I cannot fit everything I want to say in one post. I will tell you about the best practices to avoid infections in my next one.
Meanwhile, have a good crop!
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