A Homemade Anti-Fungal Spray

IMG 2632 1024x768 A Homemade Anti Fungal Spray

I have an amazing espalier rosebush in my backyard this year that is setting records with the sheer amount of blooms on it.  Unfortunately it’s also suddenly covered in black spot fungus, and needs some major help right now.

Black spot is caused by a fungal infestation that occurs in wet locations, or humid places.  It can be triggered by late evening watering, or misting sprinklers, and it spreads rapidly on roses if it’s not caught right away and pruned out.  For bushes with major black spot problems a store-bought anti-fungal spray, or an application of horticultural oil can work adequately, but for the DIYers like myself, a home remedy will fix the problem and save you the gas and pocket money.


  • Vegetable Oil
  • Water
  • Liquid Dish soap
  • One 25-32 oz. spray bottle (reuse a windex bottle, or purchase a commercial equivalent)


Combine 1/2 a teaspoon of dish soap with 1/2 a teaspoon of vegetable oil in your spray bottle, and fill completely with water, leaving only enough room for the straw and cap to screw on without overflow.  Lightly shake, and then liberally spray this anti-fungal spray all over your roses, leaves, blooms and all.

For the next three weeks apply this recipe to your roses, and you should see results quickly.  For added benefit, if you wash your dishes by hand in the sink you should transfer the soapy sink water to a pail or watering can, and use that water to hydrate the base of your rose bushes.  Gentle soapy water can temporarily kill any fungus living in the mulch, or the soil at the base of the plant, and prevent the fungus from attacking your roses again in the near future.

Your Thoughts: Do you have a recipe that you use to control fungal problems in your garden?  Leave your recipe in the comments section for other gardeners!

About Amy


  1. How often should you spray them. Do you think the mulch around it could be causing the fungus. Is there a difference between black fungus and rust?

    I wonder if this works for rust too?

  2. Amy says:

    I would spray them once per week. The fungus can live in the mulch beds around roses, and then spread to the leaves when you are watering the area through the splash water. One way to prevent further spread of the fungal infection is to avoid watering your roses at dusk, when the moisture can linger in the cooler temperatures and provide an optimal breeding ground. When you treat the roses, spray the mulch bed area as well to better control the Black Spot.

  3. caroline scott says:

    Hi Anna, thanks for this, so easy to do. I’m going to do this today :)

  4. Sara says:

    Can you spray them more than once a week?

  5. Amy Sullivan says:

    I’d like to Pin this on one of my boards on Pinterest. Are you on there? Thanks!

  6. Sam says:

    Will this work on any plant ? My bay tree is showing same spots

  7. Anila Sushil says:

    Hi ….thanks a lot for this advice…..almost all my rose plants have black spots.

  8. Myriam says:

    Will this work on a japanese maple tree? Thank you for the info.

  9. Sandy says:

    I just bought some rose bushes wondering if I should spray them before I plant them in case they have something I can’t see right now (a prevention?!)
    Thanks in advance!

  10. Billy Ross says:

    for use on hydrangia

  11. Billy Ross says:


  12. Kerrie says:

    Just wondering if it would help to prune my roses way back to help kill the fungus then spray. Any advice is appreciated.

  13. Dulcinea Rodriguez says:

    How do you efficiently use this formula if the rose bushes are very large and all affected and spraying all of them with a spray bottle would be a huge undertaking? Is this a formula that can be made in large quantities and poured at the base of the roses? Thank you!

  14. Kim says:

    My blueberry blush had something that looks like black spot to. Would this recipe work on that to?

  15. Vickie says:

    I used this formula on all my rose bushes which were lined up in a row, but I pruned first, removed some of the old mulch and sprayed on the ground and on the new mulch. It worked as well, if not better than the sprays you can buy and you can’t beat the price. I have tried it on hydrangeas also and I haven’t seen the problem at all there. Considering the ingredients, I would use this on any flowering plant that shows signs of spotting.

  16. Tom says:

    Will this formula work for Blueberries?

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