Preventing + Managing Fungal Disease

rusty garlic

By far and away the most common cause of garden disease is airborne fungi. 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 feel happiness filled knowing my spray of EM and nettle tea has leaf surfaces colonised with good guys, in a timely manner.

Prevention via holistic thinking

Drone shot of edible backyard nz

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 fresh manures, and avoid overdosing on anything no matter how natural. For very best results stay away from artificial fertilisers.

Little and often is powerful. With a capital P. It’s steady and solid, like eating a bowl of fresh picked leafy greens everyday, an evening glass of kvass or a daily stretch. Use gentle inputs like herbs, leaves, seaweed and 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.

Biological Fungicides

choose the best soil in your garden

Biological fungicides manage fungi without destroying a single hair on your gardens head. They are the longterm solution we seek, outcompeting pathogenic fungi restoring balance and increasing the biological life in your garden – thus leaving it better + stronger!

A completely different approach to traditional fungicides that kill all life – pathogenic and biological. They work immediately, yes – but the collateral damage is enormous. Residues on your dinner plate, leaching into the waterways and a bereft soil that needs much repair and wont grow crops as well in the future without alot of extra inputs like compost and fertiliser. So inefficient, don’t you agree.

Because these aren’t killers you need to use these early for them to work. Get hold of a bottle in winter, ready to spray emerging shoots/ foliage in spring.


zuchinni and living mulch mustard and marigold

Yes milk! An awesome fungal preventative for vegies with a two step benefit – calcium inhibits the growth of fungal spores and ferroglobulin protein in whey is toxic to fungus. Dilute 1:10 and spray weekly as a preventative where you usually have issues.

Fungicides: Sulfur + Copper Sprays

Can I encourage you to stay your hand? Fungicides have become a habit, an easy quick solution but they are super strong. An emergency call for growers with a crop for sale that are relying on the income but otherwise lets look to other ways before wiping out all the carefully cultivated beneficial fungi and bees in your garden. Your best bet by far is to breathe. Stay calm and think carefully about the bigger picture before acting.


  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

  8. Christopher Graves says

    Hi Kath,
    I’ve been spraying our fruit trees & veggie gardens with EM & Nitrosol in combination to great effect for the past two years. Our previously canker-ridden lemons now sport smooth, shiny skins and we no longer suffer black mould – miraculous!
    My question is about EM’s longevity; I bought 5ltrs of concentrate two years ago & have about half left after making two x 30ltr batches. May I use my remaining concentrate past the February, 2020 expiry date?
    We love your monthly letters – such sage & practical guidance can only come from a very wise woman πŸ˜‰
    Best to you,
    Chris & Alison
    Waitakere Ranges
    West Auckland

    • Thanks for your note Chris – such a thrill turning disease and misery around! Makes gardening a joy when our plants are in fine form. EM is a living product though so best before dates are a real thing. I’d use it up as soon as. If you need more help here contact EM hq – they’re happy to help. Love Kath

  9. Hi Kath,

    With the milk spray do I keep spraying it weekly during srping only?

    I have peach trees that suffer from leaf curl ( I usually just pick teh diseased leafs off and teh tree seems to do alright) I also have rasberries that get rust, unfortunetly this often effect teh fruits. Will also see fi I can find any wild nettles on my next walk to try the nettle tea. Would I have one week off the milk and use the nettle tea?