Biological Fungicides

Pear Scab

Cankers, oozing sap, fruit scab, fruit rot, leaf spots or leaf curl, and are all signs that pathogenic fungi/ bacteria are out competing beneficial fungi/ bacteria, on your fruit trees. It’s a numbers game. Simple as that. Whoever owns the space, rules the day. Your job is to turn the equation on its head, so that the beneficials rule the roost and fill the space, leaving no room for the pathogens. It really is that simple, and we have the answers at hand. Allay the panic, my friends.

Before we get going with the practical stuff, lets clear your mind of the wish for an instant fix. Our solutions lie within the web of life. A web is resilient because of it’s many strands. When a few break, the rest hold the ship steady while the organisms for repair, swoop in allowing life, in all its glory, to continue on. The health of your garden, is a web, it rests on many strands. There are no instant fixes in a resilient system.


crabapple blossoming in long grass in the orchard

Best garden health springs from a solid, wise set up. Read through my healthy fruit tree game plan – step by step guiding you, to resilient fruit trees. Whenever you get stuck, revisit this information and remind yourself of your holistic path. Use it as a check in when anything goes awry, at the same time asking yourself “What does my garden (as a whole), need more, or less of?”

Its entirely possible to sidestep outrageous populations of pathogenic fungi, they aren’t inevitable you know! New gardens, and gardens transitioning to a holistic style, are more prone because they lack the necessary diversity of life, but it doesn’t take long to build. Stay the path, and all is coming.

Biological Fungicides

Tui feeding on flax flowers blossoming apples in the background

Biological fungicides are the product to turn to, when pathogens start to dominate. They’re well proven in organic grape and kiwifruit orchards, but, once again, a new mind set is required – they’re very different from the ‘instant fix’ fungicides we’ve been used to.

  • Biological fungicides are alive! Like EM, or compost tea – they have a use by date, so buy small and use up. Sharing a bottle is a great idea.
  • They perform best in a diverse, natural, living environment – be sure to be heading in this direction.
  • They need to be applied early, onto emerging foliage in spring. This gives the beneficial organisms time to establish and get a head start on the pathogens. Repeat as required, following the advice on the bottle.

Biological fungicides are not easy to get for the home gardener, but our asking for them will make them so. Ask for NZ made biological fungicide or Botryzen. Here’s a list of Botryzen stockists. Commercial packs are a great option for co-ops.

If a particular tree is consistently hammered by disease in your carefully crafted set up – consider letting it go. Find a variety better suited to your conditions. Local gardeners are great help here.

Copper + Sulfur

I used to advise copper, and or sulfur, to clean up poorly fruit trees before kicking off a holistic regime, but now that biological fungicides are on the market, there’s no need.

I hope to stay your hand in the use of copper and sulfur. The environmental damage is enormous – residues on your dinner plate, leaching into water tables and killing off of soil life. Without life, soil cannot function at optimum – nutrient conversion, disease management and immune support are all compromised ergo lots of compost and fert is needed for cropping. So inefficient!

Add life instead, and strengthen your garden web.


  1. Kara Wright says

    Hi – Could you please tell me if I can use copper and lime sulphur sprays on citrus? I have what look like rust spots on my lemon trees at the moment. Thanks!

    • Good to check – most definately not lime sulfur! You can use copper – usually late autumn depending on what you’ve got going on. How about you send through a piccy.

  2. Hi Kath,
    Avo,s they seem to have quite yellow leaves?
    How best to make soil ph about 6.7
    cheers Carina

  3. Shona McKee says

    Hi Kath what do you use on Codling moth which my apple trees were suffering from last Summer?