We’ve had a really wet spring here in East Texas so far! Unless you’re on a Black spot prevention program for your roses, they most likely have been infected.

What Exactly is Black Spot?

Black spot is a fungal disease that can devastate roses. The fungus develops as black spots on the leaves, and over time, causes the leaves to turn yellow and drop off. Aside from looking unsightly, it can weaken the rose plant overall. Black spot thrives during hot, humid, or rainy summers and hot days with cool, damp nights.

What Does Black Spot Do?

Black spot will look like somewhat circular black spots on leaves. It usually occurs on the upper sides of leaves, but can also develop on the undersides. The outer margins of the black circles are ragged or feathery and they are usually surrounded by a ring of yellow.

Spots begin on the lower leaves and move upward. They can appear as early as when the leaves first unfurl. These spots can enlarge and eventually merge. Affected leaves often fall off the plants, and if left unchecked, the entire plant can defoliate.

The fungus can also infect young canes, causing dark purple or black blisters on the canes, and even the flowers may show some red spotting. Infected plants will set fewer flower buds and without leaves, the plants become stressed and susceptible to more problems.

How do I treat Black Spot?

Black spot is easily treated with a Systemic Disease Control spray. With the active ingredient being Propiconazole (say that 5 times fast!). The systemic disease control will be absorbed up into the plant, so there’s no chance of washing away! You can find Systemic Disease Control at THGC today!