Yellowing Apple Leaves

Asked July 11, 2017, 10:28 AM EDT

I have a yard in Boyds, MD on reclaimed soil that was compacted for house building. It is red clay with a minimum of organic matter that runs alkaline. (I fertilize the adjacent lawn with ammonium sulphate every few years with turf trust in between). three years ago I planted three apple trees into amended soil and fertilize with Plant Trust in the fall and supplement with fruit tree stakes (Vigoro) in the spring. Because I am not an attentive gardener, they have lots of issues (fire blight, etc) which I try to take care of, but the one problem I cannot successfully diagnose (or fix) is a persistent yellowing of the leaves of one of the trees (probably a Honeycrisp). Last year, suspecting lack of iron because of the alkaline soil, I acidified the soil with ferrous sulphate, no change (but now my soil near the tree is pH 5.8 (ugh, I'll have to fix that). In case it was lack of magnesium, I sprinkled some epsom salts and gave foliar sprays of same last year, no change. My garden shop recommended calcium, so I am spraying with calcium nitrate, no change. Can you help me diagnose and treat this problem? Many thanks! See attached photos.

Montgomery County Maryland

1 Response

We recommend that you submit a sample of your soil to a reputable soil testing lab. That will provide you with an analysis of the pH, organic matter, and macro/micro nutrient content. The test results will indicate if there is an actual magnesium deficiency, for example. It is better to start with the test, and then you will be able to amend the soil accordingly.
See the following web page on how to submit a soil sample.

Here is a list of recommended labs where you can send your soil sample.

We recommend that you hold off on adding any more fertilizers until you have your soil test results. We never recommend using the fertilizer stakes. The nutrients do not distribute evenly and they increase the salt content in the soil.

To help improve your soil structure and fertility, we recommend top-dressing the soil with an inch of compost once a year. This can help alleviate micro-nutrient deficiencies.

If you need assistance interpreting your soil test report and guidance on amendments to use to correct specific deficiencies, please don't hesitate to contact us again.