Spring Disease: Managing Fungus

By far and away the most common cause of garden disease is airborne fungi and the mild moist conditions of spring set the scene for primary infections of rust, black spot, leaf curl, shot hole, brown rot and other fungal delights. As I write this it’s raining and cool, the kind of conditions that strike fear in a growers heart. I hate to sound smug, but I feel happiness filled knowing my mid week biological spray of EM and seaweed, have leaf surfaces colonised with good guys, in a timely manner.

Prevention is smart, especially if your garden is prone.


  • Airflow is key. Create space around vulnerable plants like roses and peaches with good pruning and keep vegetables like celery and garlic weed free.
  • Raindrops flick spores from infected plant debris back up onto plants. Collecting up infected matter is a small task with big outcomes. Minimise the splash back effect with mulch.
  • Beneficial fungi out-competes pathogenic fungi. Colonise the surface of your plants and soil regularly with aerated compost tea, good quality fermented liquid seaweed or EM
  • There’s a two step benefit to spraying milk – calcium inhibits the growth of fungal spores and ferrugobulin protein in whey is toxic to fungus. Dilute 1:10 and spray weekly as a preventative.
  • Rotate your crops

Make A Fermented Herbal Liquid Feed


Fermented herbal teas keep plant immunity high and leaf cuticle primed to resist attack. Stinging nettle to the rescue!

Place a bucket in a warm sunny spot. Half fill an onion bag with fresh cut nettles (not in flower or seed), and stomp on them to crush them a bit. Tie the sack making like a giant teabag, and pop it into the bucket. Top up with non chlorinated water.

Stir daily by squashing the bag of nettles then whirling round the edges to create a vortex – oxygenation is key to a healthy microbial brew. It’s ready to use when it stops bubbling (in about a fortnight). Empty the contents of the tea bag onto your compost pile.

To stop my backpack sprayer from blocking up, I pour the brew into another bucket through a bit of muslin then decant it into a clean, labelled bottle. Store in a dark cool place where it’ll stay vital for 6 months. Foliar spray at 1:20 dilution throughout spring.

The Whole System

Beautiful sunshine photo of Edible Backyard with a cloche net over the brassicas

We are what we eat, and so too the garden. Too much rich stuff brings as many problems as not enough. It’s easy to get carried away with “more is better” but big doses of strong inputs make for strong reactions in our soils that grow lush, sweet vulnerable plants. Tread carefully with bought composts, fresh manures and for best results stay away from artificial fertilisers.

Little and often is powerful. With a capital P. It’s steady and solid, like a daily dose of yoghurt, an evening glass of kombucha or an apple a day. As are gentle inputs like herbs, leaves, seaweed and homemade compost – these are things that soil understands and quickly assimilates because together they’ve been at this business of soil building a very long time.

This kind of gardening grows plants that are a bit less lush but more fruitful with robust cells less susceptible to pest and disease and richer in nutrients. Better for the earth, better for us – we are winning all the way here.

There is no silver bullet friends. It’s the coming together of many things, especially your own quiet observations and wonderings.

Fungicide: Pro’s and Con’s

Once fungus gets a grip – it’s really hard to manage naturally. If fungus gets away on you, repeat sprays of sulfur will stay the infection. Without sending you into an anxious spin – be aware that sulfur sprays (copper too) are indiscriminate – beneficial fungi gets wiped as well. So for me – this is an emergency call. I have uprooted crops to stop the spread – tomatoes with verticulum wilt is one example, rather than use a fungicide. However – last year on my garlic crop I chose to spray sulfur to save the day.


  1. Hi Kath,
    I am soon to be the owner of two lovely raised garden beds. What would you recommend I put in, in the way of soil, compost etc? I have compost ready from kitchen and garden with a bit of bokashi compost thrown in. (no longer able to dig and bury it). Any suggestions gratefully received!

    • Hi Helen – filling raised beds is a bit tricky – straight compost is way too strong. Garden soil with a fine layer of compost on top is perfect but not always achievable. Some landscape yards do a garden mix. Trenching your bokachi through the new bed will be magic to start to colonise it with beneficial bacteria. Whatever you do I recommend a greencrop before cropping as this will help settle everything and bring it together. happy gardening! Kath

  2. Alana Cornforth says

    Hi Kath

    I’ve got myself some EM, some seaweed concentrate, some neem and a spray backpack. Now I’m just wondering how frequently I should be spraying these and whether it’s ok to mix them all together to minimise the labour? I’ve got veggies, roses, and a lemon tree. The lemon tree is covered in sooty mould, ants, and aphids so really needs it all I’m guessing. I’m not sure whether I should be spraying the neem over the veggies too though? It’s mainly leafy greens at the mo and I was also wondering how soon after spraying with the various sprays I can eat the veg/lemons? And if I want to add milk or nettles to the mix can they also be chucked in with the rest?

    Thanks for such a timely post!

    • Hey Alana
      Yes EM, seaweed and Neem go beautifully together. There is no withholding period for any of these wonderful things although Neem brings a strange taste! I recommend harvesting for the day and then spraying. As an all round tonic I’d go for once a month over the whole garden – roses respond really well and I LOVE one brew for everything. I use this same on my fruit trees too.
      As for your lemon this brew is exactly what it needs to get on top of the aphids and build it’s strength up for the season to come. I would spray weekly until the aphid infestation disappears. So timely to get on top of these sucking critters before the heat comes and the population booms. Once you’ve sorted them out, a monthly spray should keep on top of it.
      You can add nettles to the brew for sure. I hear ya about time efficiency!
      But as for milk – I do a separate spray here. I have hardly ever required it and when it’s needed ie first signs of fungus (not a curative so needs to be used when the problem is small), I can quickly mix up a milk spray and get it on without mucking about.
      I think you’ll find that if you are using a monthly biological brew your garden will be rocking and rolling πŸ™‚ Enjoy your backpack!
      All the best Kath

  3. Alana Cornforth says

    Thanks Kath!

  4. Cath Goodrick says

    Hi Kath
    Do you recommend a particular species of stinging nettle? My googling is leading me towards Urtica dioica…
    Thanks Cath 😊

  5. Do you need lid on the container when you make this or not?

  6. Hi Kath
    I’m reading above comments… Just wondering for all round fruit trees and flowering plants (inc roses) could I just use EM and seaweed brew? Or is the neem pretty essential? Stone fruit trees currently suffering mild leaf curl and roses moderate aphid infestation (though a lot of calendula around them), if that makes a difference πŸ™‚
    Thank you so much x

    • Yes Julie – it is! I’m all about (as much as possible) one treatment for all and these biological sprays are just that. Your roses will need the Neem for the aphids. As it happens its a good idea in spring for fruit trees to manage pests. Remember the key to Neem is the repeat sprays ok.
      happy gardening

  7. Annette Vessey says

    Hi Kath, my apricot tree has silver leaf. Can you help me..

    • Oh no – are you sure its silverleaf Annette, thats the first step here. Whats happening? A few things can look like silverleaf.

      Once you are sure manage it like this – Prune out infected branch going to back to clean wood (ie no internal brown stains) using clean as tools and burning the wood immediately after. Spray with EM to innoculate the tree and pruning wound with beneficial organisms. If the infection isn’t too far gone you can use vinevax/ trichoderma dowels with good success. This wont clean up existing damage ok it innoculates the tree to minimise spread. Your local hort/ ag supply store will have them.

      all the best