What Is That White Mold On My Plumeria And Other Plants And What Can I Do About It?

Question

I have been squirting a 5% neem and water solution on it. It comes back. I use the flat sprayer on the hose and really turn on the pressure to clean it off and it comes back. I dont want to lose any leaves. The soil her is very sandy, poor but good drainage. Plants get lots of sun. Only one plumeria out of 4 gets and t hey are quite separated. Now a plant whose name I forget get it. I’ll look that one up. Very common n FL also used as a flowering hedge. Comes in dwarf also and red, orange, yellow, or coral flower clusters. This one is also far from the others. Could I be overwatering?

Answer 1

It sounds like powdery mildew, but make sure it isn't mealybugs which leave white cottony growth at leaf and stem joints. (info below). Powdery mildew can be treated with a fungicide suggested in the article below, however prevention is more effective than trying to remedy a fungal infection.

Most plants are not permanently harmed by powdery mildew except for fruit plants and if the mildew continues year after year.

https://www.gardeningknowhow.com/plant-problems/disease/get-the-cure-for-powdery-mildew.htm

https://www.gardeningknowhow.com/ornamental/flowers/plumeria/pest-control-for-plumerias.htm

https://www.gardeningknowhow.com/ornamental/flowers/plumeria/growing-plumeria.htm

Overwatering probably isn't causing the mildew as much as humidity. Make sure you don't wet the leaves when you water, always water from below.