The energy and excitement of spring is settling into the realization that now we have to take care of all those plants we just had to have for this year’s garden. Last month we talked about some options for Organic Pest Control. This month, let’s talk about Fungus.
There are lots of different fungi – everything from Black Spot on your favorite rose bush to Blight on your prize tomatoes. Fungus controls fall into two basic categories – preventative and curative. I want to be clear that your plant care routines, especially plant placement and watering routines, are your best defense, as well as a very likely cause, of your fungus issues. Plants spaced too closely together, low light, over and under watering and poor nutrition can stress plants and make them easy targets for fungus problems.
The controls in this category are the ones that are most familiar to experienced gardeners and include products containing sulfur and some form of horticultural oil such as neem oil.
Sulfur – in the simplest terms, sulfur works by “burning” off the offending fungus. It will also do moderate damage to surrounding live tissue, so be careful. To be successful it needs to be reapplied as directed on the label. Dr. Earth and Safers are two common brands that contain sulfur.
Neem Oil – works by coating the tissue with the oil so that fungus spores cannot take hold. This is why it states on the label to spray both the top and the bottom of the leaves. The oil wears off relatively quickly so it’s critical that you reapply at the correct interval as stated on the label. You also need to reapply all summer long. Neem oil can also be seen as a preventative. If you have plants you know are susceptible to fungus and you start on a program before problems appear, it will keep fungus at bay.
These products are a little newer and are very effective. These products are a bit like getting a flu shot in the fall.
Tebuconazol – is the active ingredient in some Bayer Lawn & Garden Products. It’s a systemic fungicide and those are kind of hard to find – especially for outdoors. It’s very effective against most common types of fungus found in northwest Washington. It’s not listed for edibles and it needs to be reapplied every 6-8 weeks. My wife and I have had great success using it on the roses.
Bacillus Subtilis – is bacteria found in a product called Serenade. It’s a live bacteria that actually attacks the fungus spores. It’s very effective against Powdery Mildew and many other types of fungus that show up on flowers. Much like neem oil it can be considered both a preventative and a curative depending on when you use it. If using as a preventative, you should start using it early in the season and apply every 3-4 weeks. Serenade comes in a ready-to-use formula and a concentrate. The concentrate contains dormant bacteria spores that are “awakened” when you add water. The shelf life for this product after water is added is approximately 48-72 hours.
Compost Tea – while not really a fungicide it has been shown in numerous studies that the use of compost teas, both as a drench on a regular basis and as a foliar spray, are excellent at preventing blights on tomatoes, pumpkins and squash. If you are a composter you can get as complicated as you want on your brew or simply place compost wrapped in cheesecloth in water for 24-48 hours stirring occasionally. Malibu Compost Tea is available in our stores. 4 small tea bags make up to 20 gallons (5 gallons per bag). It takes 24 hours to “steep” and you throw the tea bag back into your compost pile when you are done.
We have lots of products to help you with the fungus problems you’re going to experience in your garden. The number one defense against fungus is you! Your garden is a living, breathing thing. Treat it like a cherished pet or child and it will reward you in many ways.
Next month we’ll discuss watering tips for the NW drought (drought…really never thought I would use that word my world!). See you then.