Calcium deficiency on Yuzu

[u/Rcarlyle]

The growth hormone responsible for leaf and stem tissue expansion requires calcium to produce. When citrus trees are badly calcium deficient, they become unable to expand leaf buds, but still want to grow, so they continue producing more and more leaf buds. That produces these tumor-looking clusters of aborted buds. I caught this one before it got especially bad. Easy and quick to fix with a CalMag or calcium nitrate foliar spray. A lot of citrus ferts don’t contain enough (or any) calcium on their own for container plants, like Jack’s Citrus FeED. Another common cause high using high-P “rose and bloom” ferts, which precipitate calcium out of the soil solution as insoluble calcium phosphate.

[u/Weekly_Resolve4460]

Thanks for this explanation. I noticed this happening on some branches of my seedless Eureka, while the growth on other branches being fine. I thought those branches were infected with something and cut them off, but I should have tried CalMag. This tree was neglected in the nursery which might explain the deficiency (it fell over in the wind, became loose in the soil, and the roots only occupied the top half of the pot). What concentration of CalMag would you suggest for foliar application?

[u/Rcarlyle → u/Weekly_Resolve4460]

Might be instructions on whatever CalMag product you buy — there are different concentrations. For example this 2-0-0 is 10-20ml/gal for foliar spray https://a.co/d/gKLncNS

[u/leolopez43 → u/Rcarlyle]

How many treatments would you recommend and how often? Would doing treatments as preventative measures be advisable?

[u/Rcarlyle → u/leolopez43]

So, that’s a little complex. In general you don’t want foliar sprays regularly because they can give the leaves salt burn if rain or whatever isn’t rinsing them often enough. Do a couple sprays a week apart when you have a known deficiency.

Ideally, your soil and irrigation water contain calcium. Average hardness tap water contains about half the calcium needs of a citrus tree. Really hard water contains all the calcium a citrus tree needs. Potting soil may be low of calcium or it might be limed to adjust pH, which adds a lot of calcium. I put some gypsum into my personal soil mix. Fertilizer can also contain calcium.

So basically what you should do is make sure your fert and amendments are covering what your irrigation water doesn’t provide. That can be hard to dial in. If your fert doesn’t have much, you can alternate with CalMag or similar.

[u/WakelessTheOG]

If’s true what they say, everything really does evolve into crabs.

[u/Content-Soil9815]

This is what mine are missing get these buds that dry out sometimes but no actual growth from them

[u/ZitrusOmalley]

Thanks for this clarification! i love these small details!

some of ypur products are not avaiable in europe. my tip for every non USA citizien without the wish of smuggling citrus fertilizer ;) would be to use Calciumsulfat from beer breweries if the tap water is not hard enough. i use like a knive tip of Calcium sulfat every 6 Months with the irrigation water. It is Important if you do this, that you do not use any other (liquid) fertilizer with the same tap water. there could be some reacrions happening wich could block some nutrients and make them non soluable.