Plant Diseases

Hey gardeners!

Did you know that plants can get sick, just like people? Today we’re going to talk about plant diseases!

Plant diseases can be caused by biotic factors (pathogens) and abiotic factors (anything nonliving). A pathogen is just any microorganism that can cause disease, like bacteria, viruses, and fungi. If you’ve ever come down with the common cold, you’ve experienced a pathogen, too! Pathogen-caused diseases are infectious, meaning they can spread from one plant to another. Some plants are vulnerable to more kinds of pathogens than others.

(Sidenote: although they’re considered pathogens, there’s an ongoing debate about whether or not viruses are living. It’s not as simple a definition as you might think! Here’s an article on that: https://askabiologist.asu.edu/questions/are-viruses-alive)

Abiotic causes of disease are usually some kind of environmental stress caused by less-than-ideal growing conditions—think excess heat, too much or too little moisture, or nutrient deficiencies. These are considered non-infectious because they can’t spread from plant to plant (although they might affect multiple plants in an area!).

So, what can you do?

One way to limit the spread of plant diseases in your garden is to choose disease-resistant varieties—although no plant is immune to every pathogen, you can at least plant crops that are susceptible to less of them. Make sure to give your plants enough space—if they’re too close together, you’ll get less airflow between them, which makes it easier for leaf-based fungal diseases to spread.

In a similar vein, water plants in the morning, if possible. This gives the leaves time to dry while it’s still daytime, which reduces the risk of disease—wet leaves are a breeding ground for fungi and bacteria!

Also, it’s a good idea to rotate your plants every year. Crops in the same family are often vulnerable to the same pests and diseases, and rotating your garden keeps these from building up. Plus, it’s good for soil health—planting the same crop in a bed year after year will often result in reduced soil fertility.

Finally, here’s a neat diagnostic tool from the University of Minnesota Extension. You can select your plant and any symptoms you observe (wilting, black spots, holes in leaves, etc.) and it will offer information on possible causes! https://apps.extension.umn.edu/garden/diagnose/plant