I'd wait until late March, early April. Interested to hear what sort of success you have with it?

I treated a Chinese Chestnut and only saw moderate improvements overall. There were a couple of dark green branches but the chlorosis was still prevalent (but not quite as severe over the rest of the tree.

Some say that sulfur applied in the root-zone of the tree is a good method of treatment. Not sure how/where this is bought/supplied, but a quick web-search would answer that.

general search: https://duckduckgo.com/?q=Medicap+iron+tree+implants&t=ffcm&ia=products

last couple paragraphs of this one: http://www.treecareproducts.com/Application%20Guide/Application%20Guide.htm

website of your product: http://acecap-medicap.com/

medicap application guide.. which seems to be the same as the second above: http://acecap-medicap.com/Application%20Guide/Application%20Guide.htm

Thanks all for the helpful comments. I’ll look to apply late March and see how it goes

Here's an example of elemental sulfur:

https://www.homedepot.com/p/20-lb-Fast-Acting-Sulfur-100510896/203342315

Always wondered about the effectiveness of sulfur for >6" diameter trees? Surface application on limestone derived clay soils seems unlikely to have a great effect at tree root level?

Hello All! I wanted to circle back after my initial post. I did end up applying the iron supplement tree implacts in late March '19 and the tree has been flourishing ever since the leaves started coming out in spring. So i am very happy with that. This is the first time the tree has looked this good for the entire season. The directions on the supplement say it may need to be reapplied every 2-3 seasons. Any suggestions on if I should just re-apply in spring '21 or should I wait until/if i see any yellowing or signs of the chlorosis again first?