Downy Mildew On Cole Crops: How to Identify and Control It

As a cole crop grower, you may have encountered problems with downy mildew. This disease can wreak havoc on your crops, causing significant yield loss and reducing the quality of your produce. In this article, we'll discuss how to identify downy mildew on cole crops and provide tips on how to control it.

What is Downy Mildew?

Downy mildew is a fungal disease that affects cole crops such as broccoli, cauliflower, cabbage, kale, and brussels sprouts. It is caused by the pathogen Peronospora parasitica. The disease thrives in cool, moist conditions, making cole crops particularly susceptible to infection during early spring and late fall.

The first sign of downy mildew on cole crops is the appearance of yellowish spots on the upper surface of leaves. These spots will eventually turn brown and develop a fuzzy appearance on the underside of the leaf. As the disease progresses, the affected leaves will begin to wilt and die off, leaving your plants vulnerable to other infections.

Identifying Downy Mildew

If you suspect that your cole crops are infected with downy mildew, it's important to properly identify the disease. Here are some key characteristics to look for:

1. Yellow Spots: As mentioned earlier, downy mildew starts as small, yellowish spots on the upper surface of leaves.
2. Fuzzy Growth: As the disease progresses, the spots will become brown and develop a fuzzy growth on the underside of the leaf. This is the result of fungal spores growing on the leaf surface.
3. Wilting Leaves: Infected leaves will begin to wilt and eventually die off. This is an indicator that the disease is spreading throughout your crop.

Controlling Downy Mildew

Preventing and controlling downy mildew requires a multi-faceted approach.

Cultural Controls

Start with proper cultural controls. This includes:

• Crop Rotation: Do not plant cole crops in the same area every year. Rotate your crops to help break the disease cycle.
• Sanitation: Keep your planting area clean by removing any infected debris or plant material. Make sure to dispose of it properly rather than composting it.
• Irrigation: Avoid overhead irrigation as this can create ideal conditions for fungal growth. Instead, use drip irrigation or soaker hoses.

Chemical Controls

Use chemical controls only if necessary. Some options include:

• Fungicides: Fungicides can be used to control downy mildew, but it's important to follow label instructions carefully. Not all fungicides are effective against downy mildew, so make sure you choose the right one for your crop.
• Biofungicides: Biofungicides are becoming more popular due to their eco-friendly nature. They work by introducing beneficial microorganisms to the soil to combat fungal diseases.

Genetic Controls

Another option is to plant resistant varieties of cole crops. Look for varieties that are specifically bred to resist downy mildew.

Downy mildew can be a serious problem for cole crop growers, but it can be controlled with proper management practices. Remember to rotate your crops, keep your planting area clean, and avoid overhead irrigation. If chemical controls are necessary, follow label instructions carefully and consider using eco-friendly biofungicides. By taking these steps, you can minimize the impact of downy mildew on your crops and ensure a successful harvest.

Yellow spots on a cole crop leaf.

Fuzzy growth on the underside of a cole crop leaf.

cole crops, downy mildew, fungal disease, crop rotation, sanitation, irrigation, fungicides, biofungicides, genetic controls