Treatment of disease with metals and trace minerals

The more I learn about growing fruit the more I realize minerals are important in disease cycles for what that’s worth. When we think of disease treatments things like boron , manganese, zinc, copper, calcium, magnesium, sulphur almost immediately come to mind. Is there a good book about these complex relationships in fruit production, disease control and minerals? Heavy metals that are very toxic to us such as lead were once the go to spray for apples. Wanting to make sure history does not repeat itself with copper sprays in my own orchard. I feel like two or three copper sprays a year is fairly safe but what are your thoughts? My trees are very responsive to magnesium. The trees green up and grow beautiful once magnesium has been applied. No doubt we are short on minerals in our soil. Most Kansas soil was stripped clear down to the clay due to poor farming practices. In 100 years the soil in my area was nearly completely destroyed by modern agriculture. Many advances in agriculture have been made now and better methods such as no till are now being used. Much has been learned by mistakes made in agriculture. Like with anything there is a learning curve.


I thought that y’all would have mag deficiency, but these articles kind of refute that.

I guess it depends on what type of soil you have. Judging by your bumper pear crop this year, it doesn’t seem you have too many deficiencies. Of course, I don’t know how you fertilize your trees.

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It’s hard to say Clark without a couple of soil tests, one for available nutrients and one for what else might be there but not available.

Most of the metals can be unhealthy in excess. Copper is one of those, however on the flip side studies back around 1900 showed a correlation between copper deficient soils and stomach cancer in Britain. Best is to keep all in balance, which is hard to do if you don’t know where your soil is starting from. If your soil’s copper levels are low, then even more copper sprays might be OK. If it’s already in excess, maybe time to find another spray if you can.

Check around on the soil tests for trace elements. I found coop extension to have outrageously high prices for those tests. There are some online/mail testing labs which include many of the trace elements in their basic tests, and they tend to be the best deal. You can ask them how they are testing, and if they tell you the available amount or the total present but not necessarily available.

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The extension office did tell my neighbor all our ground was short on magnesium. I give it in small quantities to all my trees. I use cow manure and wood chips as my other standard supplements for my trees. Sure makes them grow nice. Don’t like my trees to grow real fast but I do like them to grow.

Seems odd that if you have a clay-based soil you would be short on Mg. But I suppose anything is possible.

For a baseline, I like the labs which follow Albrecht’s system, having major elements at a certain % of CEC. It gives a good target for where you want your soil to be, rather than just guessing. Another nice thing is the lab I used ( gives most trace/minor element number too.

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Clay as your aware locks minerals up which is why I add composted manure and composted wood chips to the top of the soil. Cation exchange capacity sounds simple but it gets very complexed. Cations as you stated are there in the case of clay but not always usable without a balance of humus in the soil. There in lies part of the problem modern agriculture reduces organic material in the soil due to erosion. In the case of the dust bowl it was wind erosion that took off 20 ’ of organic rich topsoil. Soil is now lacking that balance of positive and negative particles that allows roots to uptake those nutrients. Positive particles without negative is not valuable to the plant. Anions are just as important as cations. Magnesium deficiency does seem odd but it could be compensation for locked up minerals.

Indeed it does get complex. It is not that the soil needs a balance of + and - ions, but becomes more complex than that. To some extent the roots will give off ions in exchange for what they take up. They also “feed” sugars to fungi and bacteria in exchange for elements/compounds they need. But it is a complex dance in the soil and root zone as to what can be taken up and how.

Mg levels are typically quite high in clay. In fact they recommend higher Mg for sandy soils that they want to “stick together” more. How you could have a bunch of clay and still have Mg deficiency is a puzzle. I’d be going to one of the better soil test firms and asking questions.

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That’s sound advice Steve. Last time I contacted my agent on a disease results were inconclusive. To make matters more complexed I have several types of soil on different parts of the property. It’s mostly clay loam.

I had a detailed soil analysis from a soil testing lab. I thought I was low on iron, but it turned out the iron was very, very high. I also have high potassium and phosphorus, and recommendations were not to use a multipurpose fertilizer. What was low, was magnesium, and calcium was very low. Copper was borderline. So I limed for the calcium, and to bring up my pH which was 5.3, but didn’t do anything about the others. That lab does not test for nitrogen, they just say to add it, because they say nitrogen is so transient in most soils and circumstances

One of my persimmons has had yellow leaves for 4 years. I thought it was just that variety, Saijo, or effect of the rootstock for that variety - lotus. I didn’t want to add nitrogen, which wasn’t included in the soil test. I read that adding nitrogen can cause persimmon fruits to drop. As an experiment this year, when this tree started leaving out, I added about 1/4 cup of epson salts to 2 gallons of water, and watered it into the ground around the persimmon tree. This year, the foliage is lush and dark green. I guess it was either the Magnesium or the Sulfur, or both. IT might be my imagination, but I think the flower buds look bigger and more lush, too.

For what it’s worth, my soil is also a fairly high clay soil. I guess it depends on the geologic history and what has happened in modern times as well.