Plant diseases are a huge challenge to sustainable food production

What is a plant disease?

When a plant is diseased or ill, its normal growth and function is disrupted. Plant "diseases" may severely affect the growth and reproduction of plants - and this has impacts on plant productivity.  These diseases are generally caused by living factors, or non-living factors... let's have a closer look...

Living factors

Living factors that cause plant diseases are organisms (in plants it is mostly fungi) that feed off plants for their own survival.  When doing so, they cause injury or disease to the plant (the plant is also known as the host).  Disease causing organisms are called pathogens.  Some organisms that cause plant diseases include fungi, bacteria and viruses.  These organisms are very, very small, invisible to the naked eye, thus magnifying tools like microscopes are required to see them.

Stem rust of wheat a hugely important plant disease in the world. Wheat is a staple food, and wheat flour is used to make bread, but also cookies, cake, pastries and all kinds of other products. If we are unable to control this disease, it will mean no more flour, and no more "whatever is made" with flour. Therefore the scientists of the whole world has come together to combat this disease, and ensure wheat flour production (and more importantly bread and cake for us) in future.

This is what stem rust looks like, almost like chickenpox! The plant is severely challenged as it tries to grow and reproduce (make seeds). At the same time, our chances from getting flour from such plants diminish. In some years, farmers have lost 100% of their crop to this disease. This mainly happens in third world countries, where support and resources for controlling wheat diseases are scarce.

Non-living factors

Non-living disease causing factors can also be referred to as environmental factors.  A number of factors are involved.  These include moisture stress, excess or deficiency of nutrients, soil salinity, pollution, pesticide damage and so on. So if plants do survive the challenge of diseases (or pests, which I will discuss later), then other challenges still remain.

This plant is suffering pesticide damage, after the farmer attempted to protect his crop from pests or diseases. Here, similar to what happens when the plant is infected with a disease, the green parts of the leaves are damaged. Green leaves and stems are the "production engines" of plants, and the more the green parts of the plant are damaged, the less the plant will be able to grow and reproduce, which, in wheat, severely hampers the amount of flour we will get from the plant. 

If we overcome plant diseases, we might still end up with birds or insects devouring the final produce. In the picture above, birds feasted on the kernels in the wheat ears, and left it "empty"! After harvest, in storage, the protection of the harvested wheat also remains critical, as a number of fungi and insects like to feed on the "flour" as much as we do.

I hope you enjoyed this insight into the importance of plant diseases. Everyone should know that plant health matters! 

Until next time :)