I'm having problems with rust and mildew on my Zinnia elegans. My USDA Zone is 7a SE. I'm using landscape fabric for my ground cover with driptape as irrigation to prevent splash-back on the foliage and I'm allowing plenty of spacing between the plants. They are getting about 6 hours of direct sunlight a day. Can you please suggest some other options to prevent this? I prefer organic solutions.
Fungal infections in Zinnias can be treated if they are mild or moderate. Here are some organic solutions that seem to have good results:
- **Watering early-morning**: Water early to mid-morning so the foliage has a chance to quickly dry in the sun. This, combined with the space you have provided will allow ample airflow, helping to keep fungal pathogens off of your plants.
- **Natural oil treatments**: You can often effectively treat mild to moderate fungal diseases with horticultural or plant-based oils, such as jojoba or neem oil. Start treatment as soon as you spot any fungal disease symptoms and repeat applications every seven to 10 days, or according to label directions. Fungicidal oils work only on contact, so be sure to completely cover the foliage when you spray.
- **Debris cleanup**: Fungal pathogens often overwinter in plant debris, so rake up and destroy fallen leaves and decaying plant material when the growing season ends.
Rust and mildew are common problems for Zinnia elegans, especially in wet environments.

Here are some organic solutions you can try to prevent these problems:

1. Improve air circulation: 
Adequate airflow around plants can help prevent the development of rust and mold. You can achieve this by providing enough space between plants, trimming back bare leaves and using fans to improve air circulation.

2. Water the soil, not the leaves: 
Since you are already using drip irrigation to avoid water back on the leaves, make sure the water reaches the roots and does not wet the leaves. This can be achieved by using soaker hoses or watering directly at the base of the plants.

3. Apply organic fungicides:
Organic fungicides such as neem oil, baking soda and garlic oil can help prevent rust and mildew on your zinnia. These natural compounds interrupt the growth of fungal spores and are safe to use on humans, pets and beneficial insects.

4. Covering:
Covering around the base of zinnias with organic materials, such as straw or sawdust, can help prevent rust and mold growth by maintaining soil moisture and temperature.

5. Choose resistant varieties:
Some varieties of zinnias are naturally resistant to rust and mildew. When choosing your plants, look for varieties that are labeled as resistant to these diseases.

By applying this set of tips, you can prevent the development of rust and mildew on your Zinnia elegans while encouraging the development of a healthy and vibrant garden.
It is true that improving air circulation, watering the soil, applying organic fungicides, covering the base of the zinnias , and choosing a resistant variety will aid your zinnias in fighting rust and mildew. Please let me know if you need any more help or have any further questions!