Blight is a fungus, a soil-borne fungus, and that s@#t sucks. If you don't catch & treat blight, it can wipe out your garden relatively quickly. Don't worry there are ways to cure and prevent it but first let's talk about what it is and how it spreads. When this fungus has the proper conditions, moisture, heat, and humid it releases spores that travel and land on leaves and spread the disease. It thrives under these circumstances. Have you ever noticed that you usually encounter this problem during the late spring? Spores spread from human contact, dirty tools, (why you think I always say keep your tools in a dry location), dirty gloves, insects, and especially from watering. So how you water your plants is critical.
Blight usually begins at the lower leaves and if left untreated will work its way up the plant. Remember, blight is a soil-borne fungus, so imagine you watering with overhead sprinklers or rain and it splashing up and hitting and landing on the leaves that are the reason it starts down low. Blight begins with little brown spots on leaves and if left untreated can cause severe damage. Plants will lose leafs, fruiting will suffer, and eventually, the plant will die.
Blight is known to affect;
Members of Brassica Family
How to prevent
- Overwintering is a significant issue- If you do not take care of the problem, it will return. If your garden dealt with blight during the previous growing season make sure to remove all plant matter and throw away or you run the risk of passing along the same diseases and problems. Do not compost because the spores will take up residence in your compost pile. When you apply this compost to the garden, Blight will spread and pop up everywhere. Remove all weeds and grasses from growing area.
- Mulch- I am an advocate for mulching. Applying mulch will help to create a barrier between the plant's leaves and stems from the soil. Since this is a soil-borne disease and the splashing from overhead watering and rain can create a splash in the soil causing the water to make contact with the soil and then the leaves, therefore, transferring the disease. Mulch is vital because you do not want exposed soil, infected or not.
- Drip Drop- Water from the bottom of the plant with drip irrigation, not the top. Keeping the leaves dry during the growing season is very important. Overhead watering creates that touches the leaves creates a mini microclimate that can harbor the pathogen and help it to spread
- Clean- Keep the garden area clean from plant debris. Keep tools clean. Keep gloves clean. Just because your working outside in the dirt does not mean you cannot practice a little hygiene when it comes to the garden.
- Air circulation- Do not overcrowd your plants, Air circulation helps to reduce the microclimate effect. It will decrease humidity which is a best friend of fungus. Stake or cage your plants to make sure they are not growing and falling on each other. More air circulation leads to a drier environment which is vital.
- Pruning- Remove the bottom 12-18” of growth from the plant. Pruning helps to increase air circulation and light penetration which both help alleviate fungus problems. If the infected water has no plant matter besides the stem to splash on you will be in good shape.
- Remove infected leaves- This is self-explanatory. If the infected leaves remain on the plant, you are allowing the fungus to remain on the plant. If the fungus is on the plant, it will spread to the remaining parts of the plant and the neighboring plants.
- Proactive- Spray plants proactively. Do not wait to see problems. Apply a baking soda solution (3 tablespoons of baking soda to 1 gallon of water- then mix in 1 tablespoon of vegetable oil & a few drops of dish soap ) with a spray bottle. Just spray all over the leaves, the crop, and any other crops surrounding it. If you don't want to mix your own spray you can purchase Bonide Liquid Cooper fungicide.
- Crop Rotation- Do not plant the same varieties in the same spaces year after year. Doing so can cause a buildup of pathogens in the soil which will result in infected plants.
I have found tarping the garden area to be extremely helpful with all diseases and pathogens. Before planting cover the garden site with a tarp and allow the sun and heat the temperature of the ground to over 168F for a minimum of 4 weeks. Tarping will “cook” the pathogens, viruses, and diseases out of the soil. Careful with clear plastic you will end up cooking the good and bad out of your soil in a process called solarization.
Testing your soil yearly and making sure the soil food web is alive and thriving will help to prevent you from ever even having to deal with blight.