Gardening and farming are acts that require you to be in the moment, while also looking backwards to the past and forwards into the future. Fall is a transitional time that signals to our caretaker mind to take stock, prepare for the coming season and make plans to overcome what we may have seen in the past seasons.

Immediately, we may be seeing our tree’s leaves falling, our summer vegetables slowing down, and the foliage of our plants generally turning colors and looking less vibrant. This may trigger us to want to “clean”, but we know ‘leaving the leaves’ and other debris is important for overwintering animals (right?). There is an appropriate time to remove leaves, though: when you know you’ve had diseases in your plants.

What to Look For During the Growing Season

The diligent farmer or gardener knows they need to keep a close eye on their plants as they are growing. They should be observing how plants develop; if they form spots on the leaves or deformations; if they turn an abnormal color; or any other deviation from the expected progression of growth. Noticing these patterns will help you diagnose an issue and catch it while it can be managed.

If a plant or crop does succumb to a disease or pest, it is especially important to know what killed you plant so you can make sure it doesn’t happen again. N.C. Cooperative Extension can help you with that, in most cases. We can help connect you to the Plant Disease and Insect Clinic at NC State University if we can’t help! But, the best way for us to help you is if you call us early on!

Why is This Important

Plant pathogens can survive the winter in the soil or in material left from a prior season. There are species that naturally inhabit the soil, and then there are the soil invaders that will quickly take over most of the resources in the soil. Invaders will be there while the food source is there and the feeding is easy, but their populations will dwindle when the host food source is gone. So, if you remove the leaves and debris they’ve been feeding on, they will starve and hopefully not survive to reinfect your plants next year!

Generally the survivors are root and crown pathogens, such as the bacteria responsible for diseases like Southern bacterial wilt, and fungi like Thielaviopsis or Phytophthora. There are also pathogenic nematodes, like the root-knot nematode, as well. Some fungi overwinter in the debris left behind in the form of sclerotia, which are small, truffle-like structures that can withstand the cool, wet conditions of our winter and allow a fungus to regrow when the conditions are favorable.

Best Practices- Crop Rotation and Sanitation

There are strategies you can use to leave the leaves AND control overwintering diseases.

In the case of vegetable gardens: make sure you are using crop rotation strategies in your garden. Don’t plant your tomatoes and broccoli in the same bed every year. Yes, we know this means you have to have the space to plant them in different areas each year, but this should be part of your garden planning process. Crop rotation reduces access to the pathogen’s preferred food source and is a good technique to manage pathogen populations. The naturally-occurring soil microbes live longer in the soil because they have structures and strategies that help them survive time when resources are not available or are not picky about what they consume.

Do not think twice about destroying or removing diseased tissues from your vegetable or display garden. It is far better to rip out that diseased vegetable and remove a dying branch than it is for that pathogen to spread to other plants. On your ornamental plants, make sure to discard diseased material, especially spent flowers, instead of letting it sit under your plants. You can rake up this debris and remove it, and bring back in leaves from another area! You can burn the diseased debris in a burn pile or put it in the dumpster. Just don’t put it in your compost pile! Some pathogens can survive in a home compost pile.

If you have recurring disease issues, look into resistant cultivars of plants or consider removing a plant and replacing it with a more appropriate plant. If you are not sure of what you are dealing with, don’t hesitate to reach out to N.C. Cooperative Extension.

Balance

Removing diseased materials in a few select areas of your garden are not going to negatively impact your pollinators in the long run. You are in control of your garden or farm. You have the power to manage pests and diseases as a land manager. All management strategies have benefits and costs associated with them. It is better to sacrifice some leaves in the short term to solve a potentially long-term issue with a plant pathogen.