Top 5 Ways To Prevent Or Stop Plant Diseases In Your Organic Garden
1. Focus On Soil Health (Prevention)
Biological systems and lifeforms are complex. As such, it’s much easier to practice prevention than treatment. The same applies to people. For instance, it’s much easier NOT to ingest sodas and highly processed foods than it is to try to treat Type II Diabetes.
Likewise, it’s important for you to understand that the foundation of any organic garden or farm is the health of its soil. Without healthy soil, trying to grow plants will be a never-ending battle of treating symptoms.
Healthy soil means soil that has all the biological life forms present to:
- feed your plants all the macro and micronutrients they need while optimally cycling nutrients and water, and
- protect your plants from pathogenic/disease-causing organisms.
2. Stop Powdery Mildew on Squash, Pumpkins, Cukes, and Other Cucurbits
Powdery mildew is the common name given to any number of fast-growing, airborne fungal diseases that cause white powdery patches on the leaves of cucurbits and other garden plants. Left untreated, powdery mildew causes the leaves to turn brown and dry out, eventually killing the plant.
Powdery mildew can be easily prevented using organic methods. The easiest, most proven method of treatment involves milk. Make a mixture of milk and water (30% milk to 70% water is fine) and spray it evenly on the surface of the leaves of affected plants during the morning on a sunny day.
Any type of milk will work: skim or whole. In studies, this method has proven to be as effective as any synthetic fungicide in stopping powdery mildew, although scientists aren’t quite sure how it works (likely an antiseptic effect resulting from the sun burning the fungus as it’s bound by the milk protein).
3. Prevent or Stop Tomato Foliar Diseases
If you live in the hot humid south, it’s extremely unlikely that you’ll get through a whole summer without seeing some type of foliar (leaf) disease on your tomato plants, especially if you’ve been growing tomatoes for more than a year without “crop rotation” (e.g. not planting the same type of plant in the same spot year after year). There are probably hundreds if not thousands of bacterial, fungal, or viral tomato foliar diseases.
What’s the best organic way to prevent or stop tomato foliar diseases? For prevention and treatment, you can try either:
- Actively Aerated Compost Tea (AACT) – You can make AACT from hot compost (Berkeley Method) or non-anaerobic worm castings (worm castings that have been stored in an airtight container, a hot place, or in a liquid will have mostly dead microbes that aren’t a good inoculate for compost tea).
- How To Use It – Apply AACT as a foliar spray throughout the growing season; also apply as a soil drench 1-2 times per year during seasonal transitions (summer > fall garden or winter > spring garden). During particularly rainy periods when disease pressure will be higher, you might want to increase application frequency.
- How It Works – The best analogy here is the human microbiome, e.g. the trillions of microorganisms in and on you that play a wide range of roles in keeping you healthy and alive. If your gut flora is out of balance, it can have profound impacts on your physical and even psychological health. The same is true with plants. By keeping their leaf surfaces coated with beneficial bacteria, fungi, etc, you make it exponentially more difficult for pathogenic microorganisms to take hold or proliferate. Similarly, you can keep soil-borne pathogens in check by applying AACT as a soil drench.
- Serenade – If you want to take the easier, store-bought approach, you can use Serenade. Serenade is OMRI listed for organic farms and gardens.
- How To Use It – Use preventatively as a foliar spray or immediately upon seeing signs of disease on your tomato plants’ leaves. You can buy it as a pre-diluted, ready-to-use spray bottle or in concentrate to mix at home as-needed.
- How It Works – Serenade is a patented strain of bacteria (Bacillus subtilis) that basically eats many types of pathogenic bacteria and fungi or outcompetes them for prime real estate on the surface of your plants. Actinovate is another excellent bio-based organic product that is also excellent at preventing or stopping plant diseases.
4. Proper Irrigation Methods
You can use drip irrigation rather than overhead irrigation or sprinklers.
Irrigating your plants with a sprinkler/overhead irrigation is less water efficient than irrigating through drip lines (overhead sprinklers can lead to water losses up to 50% due to evaporation). Also, sprinklers cause your plants’ leaves to get wet and therefore makes them more prone to infection by pathogenic fungi and bacteria (foliar diseases). If you absolutely have to use sprinklers, irrigate in the early morning to maximize water efficiency and give your plants’ leaves plenty of time to dry off!
5. Don’t Touch and Spread!
if your plants’ leaves are either: a) wet, or b) showing signs of disease (discoloration or spotting) outside of normal seasonal color changes as the weather cools, you need to learn to control your plant-touching urges. Otherwise, you might well end up spreading a foliar disease to other plants in your garden.
Be sure to practice good “clipper hygiene” by washing or disinfecting your garden tools between uses–especially if you’ve used those tools to remove diseased plants or plant foliage. Rubbing alcohol or scalding hot soapy water should do the trick.
