What is wrong with my hyssop?

Are there brown to black spots or blotches present on the leaves?

Are the leaves covered with white powder?

Are the leaves pale on their upper side and are there any dusty blisters on the undersides?

Do the roots and crowns have dark brown spots at the soil level?

Leaf spot diseases are caused by several fungi that thrive on moist leaf surfaces. Brown to black spots develops on the leaves of infected plants. These spots often come together to form larger patches of dead tissue. Pick off and discard infected leaves, and spray the vine foliage every seven to ten days with sulfur. Avoid wetting the foliage while watering the vines. Mulching around plants helps prevent fungi from being splashed up from the ground by rain.

White, powdery patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from below to keep foliage dry. Any affected leaves should be cut off and removed. The appropriate fungicidal spray will protect your plant from further infections.

Likely cause for these symptoms is a fungal disease - Rust. Provide good air circulation around plants by thining them. Avoid making leaves wet when watering. All infected leaves should be removed. Spray leaves with sulfur early in the season to prevent rust or to treat mild infections.

These symptoms indicate fungal disease Phytophthora Root and Crown Rot. Phytophthora pathogens are favored by wet conditions, and the risk of disease can be reduced with good water management. The disease tends to affect plants in poorly drained areas, where susceptible plants are surrounded by standing water or saturated soil for prolonged periods. Provide adequate drainage and know the water needs of individual plants.

Mineral deficiencies can cause tip chlorosis or necrosis or cause foliage to discolor, fade, distort, or become spotted, sometimes in a characteristic pattern that can be recognized to identify the cause. When nutrient deficiencies occur, nitrogen and iron are the most commonly seen deficiencies. Apply only the mineral found to be deficient. Excess nutrients, on the other hand, cause symptoms like leaf tip dieback, marginal leaf chlorosis, necrosis (or burn), branch dieback, and pest problems. In this case, you should provide good drainage, and use good practices during fertilization and irrigation.