Treating Iron Chlorosis In Pears and Other Fruit Trees

I live in Texas. On top of our heat and drought, I have high pH soil. In fact our ground is so basic, that our tap water will kill acid loving plants, just by watering with it.

High pH soils make certain nutrients hard to take up by your plants. For me I’m almost constantly facing iron chlorosis in pH sensitive plants. Iron Chlorosis is not necessarily a lack of iron in the soil, it’s that the high pH (basic rather than acidic soil) makes the amount of bioavailable iron lower. It’s there, but your plant’s roots can’t take it up. So, just adding more iron isn’t going to fix your plant’s issues. (Just like adding calcium to the soil won’t fix blossom end rot in tomatoes, although both can be limited by good watering practices.)

Yellow to white new growth is a symptom of iron chlorosis. The tip die back looks a bit like fireblight but the yellow and white new growth means this is iron chlorosis. Plus you will see leaves stay on the branch and the tip will bend like a shepherd’s crook if it’s fireblight.

To help a chlorotic tree, you will need to either lower your soil pH (nearly impossible if you have free lime, soil test explanations, and will take years to work up to the crown of your tree), hire an arborist to do trunk injections (very expensive) or, do what I just did, and drill holes in your tree and place implants directly into the trunk. Hopefully, these implants are going to rock my pear’s world… in a good way!

Here’s a good link to information on iron chlorosis

Timing is important with implants. You are supposed to place them in your tree while it’s dormant, or as it is waking up in spring. Another issue with implants is that you need to seat them right beneath the inner bark (inside the cambium) layer. The idea is that your tree will close the wound and the inner part of your tree is not forever exposed to outside pathogens and insects.

The best thing to do with high pH soil is: to plant plants that are better harvesters of the nutrients that they need, such as: iron, magnesium calcium etc. But, if you are planting fruits, you don’t always have that option. Trees most often susceptible to iron deficiencies are: citrus, peach, pear, apple and avocado. (Most of us growing patio citrus or avocado are growing in pots and adjusting soil pH is very simple in pot culture.)

If you have decided to grow a plant that is sensitive to high pH soil (in my case a Biscamp pear) , your next best option is to amend your planting hole with acidic options like peat or compost (not a big factor in changing pH but will help hold water evenly), sulphur and iron. Unfortunately, whatever you choose to do, it’s going to be a constant battle that will last the life of your plant.

If you amend your planting hole it’s not recommended that you replace more of 1/3 of the native soil. If you change more than that amount: you will create a pot like culture. The lazy roots, that have enjoyed your amended soil, will stop pushing outward and turn back in, towards the softer soil. Your tree will be “root bound” Just as if you had put the plant in a large pot.

You can also drill holes around the dripline and place a mixture of sulphur and iron in the holes. Unfortunately, this will take years to make a difference in the upper canopy and your tree will continue to weaken before it gets better.

I am doing a combination. I drilled holes and inserted the implants, which should affect the tree this season and for several years to come. I will add a soil correction within the next year or so with the dripline drilling option. This should help my pear tree bear and grow, without the struggle of trying to green up without enough iron.

My pear has always had chlorosis, but this last summer we got 0 rain for several months. Our hot Texas climate and dry winds burned back the almost white, chlorotic leaves. It was a sad sight. No amount of added water changed the issue and the plant was not making enough energy through photosynthesis. The leaves lacked color, and therefore lacked chlorophyll, to change light energy into food for the tree. As often happens with chlorosis one side of my tree was worse than the other. I ended up cutting some limbs out in an attempt to stop the drain of resources in my sick tree.

The drought was followed by a deluge. In late summer, we got our entire year’s worth of moisture, and the trees struggled with the opposite problem they’d been dealing with earlier in the season.

While my pear struggled in the late summer/fall, it still put out 50 pears this year. This was the first year (year 6-7) that it had many fruit. I had a few dimpled, corkey pears. That was purely a water issue. It was caused by a lack of available calcium, when I’d occasionally overwater the tree (it’s the same cause as blossom end rot in tomatoes.)

You can see from this photo that the bark is very thin on this tree. Depending on the type and age of the tree you’re working on, bark thickness will vary.

According to the directions for the medicap implants I bought, you start 6 inches up the tree from the soil level and place the implants in an upward spiral. To find out how many implants you need you use this formula:

Tree diameter (at 4 feet up the tree) x Pi (3.14) = circumference, or just measure the circumference.

Circumference ÷ 4 (or 6, your choice) = amount of implants needed.

My tree was 17 inches in circumference at 4 feet up, 17÷4 (I chose to place them 4 inches apart rather than 6) is 4.25 so I used 5 implants. This is a very important equation. Too much iron is as problematic as too little. You need to get the application rate right.

You can see bark damage from our severe drought, followed by the entire year’s worth of rain in 2 months. The treatment of the chlorosis should help the plant bounce back from its very stressful year of extreme weather.

Mark your drill spots in a spiral around your tree. Drill and place implants. Make sure they are seated below the inner bark and inside the cambium layer.

I tried using a bolt to seat the implants correctly but honestly: my husband just used the hammer, by itself, and had better luck.

I recommend a wood boring spade bit. I tried a regular 1/2 inch bit but it skipped across the bark and was impossible to drill with. (Depending on the size implant you get, your drill bit will be a different size)

So, we’ll see how this works out. There is a lot positive of feedback I’ve found on these implants and I’m excited to see what my spring holds for my treated pear.

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4 Comments Add yours

  1. Samnjoeysgrama says:

    Good luck. I hope to hear this was a success! I tried putting sand from a creek in Ft Worth around a potted cactus I had grown for years. It ate it off at the soil level! I felt terrible. If a plant wants acid, even a little base won’t make it happy.

    1. Agreed! I killed a cactus with coffee grounds. Some plants can’t take acid, some can’t take base. Some need neutral soil. But with gardening you think you know what you’re doing, until you don’t, and then you always remember the results of winging it! I am really glad I researched this before trying it and I got a diagnosis of iron chlorosis from a university who helps our local master gardeners. Trees are long term, and trying something new takes some reassurance!

  2. How fascinting. I have never heard of tree implants and would instinctively fear that drilling into the trunk would lead to fungal infections. I am very interested to hear how your tree fares. Good luck!🌞

    1. That’s exactly why they need to be seated correctly. The end of the implant spreads to cap the hole, and if it’s inside the cambium layer it should close over the cap and seal the hole. I was nervous about drilling into my tree, too. However, iron chlorosis will eventually kill a tree. And trees here face damage like this from overzealous woodpeckers. Trees are pretty good at dealing with injuries. There are enough positive reviews for this that I am trusting it to work. Plus, tree injections by arborists are the alternative, and those require drilling, too. We’ll see! I’ll update this as the season progresses. Thanks for coming by and commenting! I appreciate it.

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