What is plant disease and what are the causes?
Plant diseases (caused by pathogenic microorganisms such as fungi, oomycetes and bacteria) are widespread within agricultural systems and are often economically devastating for growers. The biological threat from pathogens accounts for about a 16% loss in global food production, and the problem is forecast to worsen (Oerke E.C, Crop losses to pests, 2016, Volume 144, Issue 1, pp. 31-43). Some examples of economically significant pathogens include Fusarium oxysporum (fusarium wilt), Botrytis cinerea (botrytis bunch rot and grey mould), Pythium spp. (root rot, damping off) and Phytophthora spp. (potato blight, crown rot, root rot etc.).
In simple terms, plant diseases are caused when a plant pathogen comes into contact with a susceptible crop, under favourable environmental conditions (see plant disease triangle below). All three factors are needed in order for plant disease to occur. This means that with changing climates we will face new emerging disease threats. Sadly, plant pathogens themselves are evolving and adapting to new environments, which could paint a bleak picture for the future. Thankfully, correctly managed plant disease strategies offer a solution, in the form of reducing the economic damage and aesthetic damage caused by diseases.
It seems logical to deduce that the only factors of the plant disease triangle which are within our control are: i) the crops we plant and ii) the elimination or reduction of plant pathogens. Traditional breeding has played a crucial role in producing pathogenic resistant crops, however, as plant pathogens themselves can evolve over time, then â€˜resistantâ€™ varieties do not remain so forever. We need to engineer longer-lasting and broad-spectrum disease resistance in crops, and transgenic approaches will play a crucial role in this. However, until genetically modified crops become more widely accepted, then this is not a valid strategy for reducing plant diseases in the near future.
Disease management strategies
That leaves us with one option, how do we reduce plant pathogens within our agricultural systems? For the last century, food production has heavily relied on chemical controls for the management of pathogens. Although, a greater understanding of the negative environmental
impact of pesticides, and an increase in plant pathogen resistance due to the overuse of pesticides, has led to a positive shift in the last decades towards integrated pest management (IPM) strategies. IPM is a strategy that focuses on prevention, monitoring, and control of plant disease, with a focus on eliminating or reducing the use of pesticides. IPM utilises a number of methods and techniques, including: focusing on early preventative methods to avoid or reduce disease; using naturally occurring pest control products, such as bio-controls or bio-stimulants; regular monitoring of disease levels to ensure disease outbreaks are caught before they spread; and when there are no other options left, and if needed, choosing an appropriate chemical product that will not disrupt beneficial microorganisms in the soil.
Soil health and its link to plant disease
There is now, more than ever before, a focus on reducing the amount of chemicals within our food chain, and reducing the dependence of food production on chemical controls. Sustainable crop protection strategies are key to ensure that we can produce enough food for our
forever growing populations. However, the development of sustainable plant protection strategies will require insight into the soil biology (the microorganisms present in the soil) and an understanding of how pest management strategies have an impact on the microorganisms present. Soil is a living organism, and good soil biology plays a huge role in helping to maintain healthy soil, so that the soil can perform its normal functions (regulating water; sustaining plant and animal life; filtering and buffering pollutants; cycling nutrients; and providing physical stability and support). Intensive agriculture has resulted in higher concentrations of plant pathogens, which has i) altered the natural dynamics of the soil biology, by increasing pathogenic microorganisms and reducing beneficial microorganisms; and ii) resulted in the intensive use of pesticides, which subsequently has even further negatively impacted and depleted the soil biology. This means that agricultural fields often have poor soil health, and cannot perform all of its functions correctly. Unless something changes, this will become a never ending cycle, as poor soil health can also result in plants becoming more susceptible to disease. The Food & Agricultural Organisation (FAO) has reported that an improvement in soil health
could increase agricultural yields and hence food production by up to 58%.
How can FungiAlert improve disease management practices sustainably?
Clearly, one of the first steps in improving disease management strategies is a deeper understanding of the health of the soil biology. FungiAlert’s revolutionary soil health test is disentangling the complexity of the soil biology, becoming one of the key tools for guiding sustainable disease management strategies. FungiAlert’s technology gives growers, for the first time, an easy and simple to use tool that can determine the presence of pathogens and beneficial microorganism in the soil. Imagine if this tool was to be used by all growers as a a pre-season screening to determine potential pathogenic threats, and to determine how healthy the soil biology is. This information would drive key agricultural decisions, such as:
- What crop to plant? If there is a high risk of disease for a particular crop in a given field, then growers may choose not to plant that crop, and may chose a crop that is not susceptible to
- What seed variety to use? A grower may choose to use a more profitable seed variety in a lower risk field. In higher risk fields, the grower may choose to use a resistant variety.
- Is a seed treatment necessary? Higher risk fields may benefit from a seed treatment (this could be a biological control treatment).
- The best crop protection strategy for the upcoming year. This allows growers to plan better IPM
Furthermore, FungiAlert’s soil-health test can allow growers to monitor and evaluate their crop protection strategies throughout the growing season. For instance, the soil health test can determine the microbial profile of the soil biology before and after the application of crop protection products (chemical or biological), giving a clear picture of how these treatments have an impact not only on the pathogen of concern, but also on the beneficial microorganisms. This could be a key driver for the uptake of more bio-control and bio-stimulant products.
Sustainable plant disease management is essential if we are to increase our food production for our growing populations. Better soil management and soil health can have a huge positive impact on food production, and furthermore, it is clear that plant disease is linked with poor soil biology. Our message today, on World Soil Day, is that if we are to improve our soil health and if we are to reduce plant disease, then it is crucial that we better understand the impact of disease management strategies on the soil biology. Only then can we build disease management strategies that are truly sustainable.