Yellowing on Meyer Lemon Might Be Magnesium Deficiency

Meyer Lemon with deficiency

Q. We have went to the nursery a couple times about this tree. First we got the water cycle correct, then iron was suggested which we did as they directed then Gold Dust was suggested. Online I read possibly the tree suffers from a magnesium issue. I thought these photos would give a better picture. All we did as directed and the tree is not responding in fact it is getting worse. I am wondering if it is because of where it was planted which is a confined root growing area. Any insight would be appreciated.

Meyer lemon another shot.

A. By looking at the leaves I have to assume this is a Meyer Lemon (which is, by the way not technically a lemon but an unknown hybrid found in a Chinese back yard by USDA researcher D. Meyer in the early 20th century). Your pictures are all pretty good with the exception of not showing a critical view of the trunk where it is just out of the soil. Just for future reference always look at and show this interface of the trunk and soil. W/o that view I have to only guess that the rootstock/trunk union is well out of the soil and we can eliminate that issue. And, a shot of the soil might show how the plant is getting watered. I have to assume drippers and I would guess they are in the same locations as when the plant was planted.

The leaves show two distinctive symptoms that often occur in concert: 1. There is some salt burn and 2. The common symptom that comes with salt issues is the magnesium deficiency. Just FYI Iron def. only occurs on the new leaves.

For the salinity (salt) issue we usually look first at the watering and with watering comes knowing if the water can even be applied uniformly all around the edge of the canopy, sometimes called the 'drip line'. Citrus are botanically a shrub with shallow and wide spreading roots that are tough to grow to maturity with drippers unless they are closely spaced in a wide band around the canopy's edge. There is one picture showing the plant is right next to a step wall with no water being applied in that zone of the root system.

I would not worry too much about adding any supplements and see if you can begin to manage a watering system of application that would give a long deep soaking water application out near the drip line. The 'soaker' hoses could be laid out on the ground out near the drip line and let it run for hours and hours to try and leach out the excess salts that may have accumulated over time with the drip system. Drip systems are fine but, due to their limited water output salts can begin to accumulate thus impacting citrus' sensitivity to salts.

Give it a long deep watering about once every few weeks from now on all during the growing season (May through October)  to supplement the regular water to leach out the salts that inevitably are deposited with the limited volume of drip systems . .This leaching watering is also the great time to add fertilizer and get it into the soil evenly all around the active roots near the drip line.

Terry Mikel