Over-fertilization results in succulent leaf blade growth that leads to an increase in the amount of brown patch, melting out, and other diseases. Perennial Flowers and Vines Roses will be completing their first major flowering period in early May. Spray modern rose varieties with fungicide on a weekly basis to control blackspot. Include Immunex fungicide in your spray rotation to extend control and give some residual. Mulch with pine straw to conserve moisture. When irrigating, apply water to the soil and eliminate wetting the foliage.
Wet foliage leads to more blackspot.
Remove old flowers to encourage the next flower cycle. Pentas will normally be perennial for us in central Louisiana. The new 'Butterfly' series of pentas are great landscape performers. Butterflies love these. Perennial salvias are also becoming very popular.