Bordeaux Mixture Preparation: Preventive Spray for black spot & other plant diseases

This is how to prepare Bordeaux mixture at the rate recommended for overwinter (dormant) spraying as a plant disease preventive. If you spray thoroughly on dormant plant, the spray will help to reduce overwintering spores (downy & powdery mildew of grapes, apple scab, etc on orchard crops). I'll use the formula today to reduce blackspot on my dormant roses.

Bordeaux mixture preparation:

For each gallon of water, separately dissolve 6.5 tsp of Copper (II) sulfate and 3 tbsp of Hydrated lime. Stir well, and let sit for 15 minutes. Strain the 2 resulting solutions together into your spray tank.

If you find these videos useful, there are a few little things you can do to help me out:

[jonnsmusich]

My local farm supply has hydrated lime. And I have copper sulfate. Made up my first paint thickness mix this spring. For tree trunks. Thanks for this tip on making a spray mix for my roses and fruit trees. Always good information on your channel.

[bruceritchings]

Thanks for the details on preparing the solution which other sources seem to have forgotten. Very well presented.

[ahsmpa]

In Pennsylvania USA farm stores sell hydrated lime. Dairy farmers use it. Thanks for the easy to understand video.

[LilDirt]

Thank you so much for such a thorough and helpful video on directions for mixing. 👍

[ignaciaforteza]

Thank you Jason. I will try to follow your valuable advice.
Do have a happy and prosperous 2021. I hope for good health for all. 🥂🙏

[coffee]

I'm so glad you're sharing this info just at the right time, right when we (at least I) need it 😊 Thank you!!🌺🌺🌺

[AndYourLittleDog]

Hand on heart, I saw black spot on some canes today and came on the channel to ask you if I could treat it now while the plants are dormant. Thank you for such eerily relevant content😂 Happy New year

[nadfoy]

Very good and useful way to make Bordeaux Mixture. Thanks. 🙏🙏

[paulmingotti]

This is invaluable, many thanks for this. 👍

[ethankoeus]

Great walkthrough! Something I've heard from people - not sure how true it is - is that builder-grade hydrated lime might contain impurities such as aluminum or heavy metals depending on the ores from which it was produced, and it's safer to use food-grade slaked lime/pickling lime (which are made of the same active ingredient, Ca(OH)2) if you're applying the mixture to plants meant for food.

One slight correction - adding the hydrated lime actually doesn't make the copper ions more active, it makes them less active! Copper sulphate is very soluble, and if applied directly, the copper ions can cause all kinds of plant damage to susceptible species. When hydrated lime is added, the increased pH causes the copper ions to precipitate out as various copper hydroxides (Cu(OH)2) and basic copper sulphates (Cu3(SO4)2(OH)2), which are less active and dissolve very slowly. Once applied to plants, the copper hydroxide and basic copper sulphate ions dissolve slightly whenever water is applied, releasing small amounts of the active copper ion - enough to kill germinating fungal spores but not enough to severely damage the plant. This is also why commercial copper fungicides often carry a warning against mixing them with acidic pesticides or with acidic fertilizers as they would release the fixed copper ions and damage the plants.

Also - not sure if Canada has this approach/viewpoint as well, but in much of the world, copper fungicides are considered a marine pollutant. Copper is very toxic to many forms of aquatic and marine life, hence farmers/growers need to ensure that the products/mixes are not dumped into or run off into systems which flow into the sea or other aquatic ecosystems.

[jeangough]

Thanks for the videos Jason Happy New Year to you and your family 🇬🇧🥂

[jensfreund]

As a hobby gardener: Thank you very much for the info. This is useful.
As a chemist: You used more than ten times the amount of hydrated lime (means Ca(OH)2 ) than can be dissolved at room temperature. This is why there is so much in the filter. You can use 10 times less and it is still a bit more than can be dissolved. With your procedure (filtering the surplus Ca(OH)2 out) you savely ensure that you get about neutral pH, so pH will not harm your plants. Mixing the two separate bottles later ensures that you do not get solid Ca(OH)2 again if temperature of the solution is raising. So your procedure is really very error tolerant. I think it will also work fine if you use much less Ca(OH)2 and save a bit of money (as long as there is still a solid part after shaking and waiting for some hours you have a saturated solution). CuSO4Hydrate is acidic and you need a bit of Ca(OH)2 (in solution of course) to bring it to a neutral pH (and since you filter out the solid part of Ca(OH)2, you never make the pH too high for the plants, even though you are using too much of it)

[ryantomkinson]

Hi Jason, thanks for this vid. It's exactly what I needed. I'm going to try this out for my first time in a couple weeks on my small apple orchard near Sechelt BC.. Great to know about the different types of lime. I'll be buying DAP.

[TimurDavletshin]

1:25 — we have similar recipe of thick lime with little copper sulfate used for painting lower part of orchard trees, roses, in smaller vineyards, etc. The only difference is that they apply it autumn and sometimes "refresh' it in March-April. I was kinda skeptical about using it on roses but after couple years of experimentation I was finally convinced in its effectiveness. It does reduce damage by slugs and leaves no space for insects to hide in bark crevices.

[MildaGoesWild]

Glad it works for you. We're not allowed to use Bordeaux mix in the UK anymore... at least not for home gardeners.

[anniehyams]

Wishing you a Happy Healthy Safe New Year and 2021 thank you for sharing the beautiful videos your tips and advice❤️😀🌹👍

[matshagstrom]

excellent presentation. sounds like a less expensive and effective way to treat plants. i was going to ask about adding an antisurfactant or some soap but realized the solution is highly alkaline so it's probably not needed.

[chandraprasad]

This year one of my double flower Azalea was afflicted by petal blight. I used a fungicide which had Carbendazim 12% + Mancozeb 63%. This fungicide caused severe leaf burns on the azalea.

[clannadgirl]

I finally found the hydrated lime. My roses are budding out. Not all, so I guess I will only spray the ones that haven’t started to leaf out?
What say you?

[kevinandlitsamcnaughton]

Great, looking forward to trying it... I hope not to late as there are buds on the roses, maybe I'll wait... just wondering about how the dormant oil factors into the mix.? Thanks.