So here we are in the middle of summer and there’s a few of us already dealing with fungal issues in the garden.
The higher rainfall we’re having but still relatively warm temperatures create the perfect humid storm for fungi like powdery mildew.
Powdery mildew shows as grey splodges on the topside of leaves and usually doesn’t rear it’s ugly head til the end of the season when plants are tired and there’s a bit more moisture (Autumn) in the air. Your cucurbits, ie. zucchini, pumpkin, cucumber etc are the most susceptible. Greenhouse/tunnel house plants can fall victim too if there’s not enough air flow.
I’ve been getting it on my potted white sage which is a horrifying first for me!
Let’s go through the battle plan together. Unfortunately once you have powdery mildew you can’t reverse its course, the best you can do is pick off the affected leaves and try to curb the spread. This is why it’s a worry to have PM now – if it’s the end of the season you have your main harvest already and the plants are going to be pulled out soon anyway.
Fungicides;
Are used to prevent fungus diseases in plants and animals. Chemical sulphur based products are widely used, but not on my watch here.
In the past, I have used watered down milk at a ratio of about 30% milk 70% water, sprayed on susceptible plants in the early evening.
Lactic acid bacteria (LAB) is traditionally used in the food industry to inhibit mould but is also used with success in the horticulture industry and is one of the main ingredients in EM, which many of our beloved gardeners use; Kath Irvine of Edible Backyard (the Edible Backyard link will take you to how Kath is tackling rust, another fun guy you don’t want at your party), Kay Baxter of Koanga Gardens, Setha of Setha Seeds for example.
Getting a fungicide that is also going to give your plants a boost like EM is pretty much win win hey!
Another product you can use is a trichoderma based application which helps the plants turn on their defence mechanisms and helps from the roots up. Daltons has a product, “Organic Bioinoculant Powder” that is easily accessible from Bunnings.
Or you can try to make your own fungicide using botanicals like I have… Black elder (Sambucus nigra) leaves contain a weak hydrocyanic acid (that’s why we don’t eat any green part of the elder plant people!). Thyme and lavender also have anti-fungal and anti-bacterial actions. Peppermint, geranium, lemongrass and of course manuka/tea tree have antifungal properties also that can be utilised in a homemade spray.
How I went about it; I grabbed a handful of elder leaves, chopped them up, I also chopped up a nice big comfrey leaf for some nutrition and soapwort (Saponaria officinalis) leaves and stems as a surfactant (a surfactant helps the goodies stick to the leaves, might nab some aphids while it’s at it too!). I then covered them with water and simmered for about 20 minutes, let cool, strained and watered it down in my 1 litre sprayer…
Now, learn from my mistakes!! You know how on hair dye packets or skin products they recommend that you test first on a patch of skin or a couple of strands of hair (who actually does that??) well I highly recommend that you do a similar thing before spraying a made up spray willy nilly. Because I actually ended up burning a lot of leaves with my concoction, I made it waaaay to strong, I watered it down with only 1 litre of water when I should’ve watered it down with at least 4 litres of water. Blimey!
So if you go the way of making your own, general recipe is;
- 1 cup of fresh herb chopped or 1/4 C of dried herb
- Simmered in water that covers the herb
- Strain and water down with 4-5litres of water
Alternatively you can use the same quantity of herbs but instead of simmering you can blend the herbs together (I would only do this if you have a blender for non-food purposes) then soak it all in 4-5litres of water.
So I can’t show you before and after photos- because remember, no fungicide is a fixer – just a preventer. There are also other pro-active things to do if you’re tackling fungi, taking off the bottom leaves of plants or any other leaves that you see that might restrict airflow, if you’re dealing with potted plants, spread them out so no leaves are touching, eliminate any areas that will create humidity.
Now credit where credit is due, an Instagram friend https://www.instagram.com/the_bro_cam/ gave me heaps of inspiration and information about fungicides and integrated pest and fungal management, this guy is super passionate about it and super knowledgeable about it too, this article I’ve written here has merely skimmed the surface of what he knows and what he shared with me!
So go people, this weather is demanding us to be pro-active in the garden, go while there’s a break in this damn rain!
If you have your own recipe that you’ve used with success let us all know in the comments~
Share your thoughts!