Q.Phoma Costaricensis In Coffee Plant
Other than copper based fungicides, what product is used to treat phoma?

Certified GKH Gardening Expert
The problem with all of the genus, Phoma, is that they are all very resistant to fungicides, or any treatment for that matter.
The best defense, going forward, will be prevention. This will come down to keeping all leaf litter and plant material off of the surface of the soil, mostly. Pair this with watering ONLY when the soil is completely dry ,down to about halfway, the container and you may beat this.
One defense that I will recommend is something that I use for my citrus when they contract hard-to-rid infections is a casting of 1/2 cup DOLOMITIC LIME and about a Tablespoon of WETTABLE SULFUR per tree, around the soil.
This can make the soil very unfavorable to fungi and quite favorable for the tree, while providing a few of the lesser nutrients- Like Carbon, Oxygen, Sulfur, Calcium, and Magnesium.
Here is an article for more information on Phoma: https://www.gardeningknowhow.com/plant-problems/disease/phoma-blight-disease.htm