Begin spraying susceptible roses weekly for black spot. To learn more, read "Black Spot of Rose" at edis.ifas.ufl.edu/pdffiles/PP/PP26800.pdf.
If the leaves take on a dusty appearance or show signs of yellowing without black or brown spotting, check for spider mites or Chilli thrips. Mites are a common problem on roses in the dry spring months. Chilli thrips are very hard to see. Feeding damage turns tender leaves and buds a bronze color. Damaged leaves curl upward and appear distorted, and the leaves will fall off the plant. Several products, including insecticidal soaps and oils, can be used to control mites. For Chilli thrips, use neem oil.
The amount of maintenance needed for your roses varies according to the kind of roses you are growing. Most modern roses, hybrid tea and grandiflora roses need weekly watering and spraying, frequent grooming to remove old flowers, fertilization after each flush of bloom and pruning and mulching in early spring. Low-maintenance roses like "Bourbon," "China," "Bermuda," "Tea" and "shrub" roses typically require minimal maintenance. For more information, visit edis.ifas.ufl.edu/pdffiles/EP/EP33900.pdf.
Theresa Badurek, urban horticulture extension agent, UF/IFAS Pinellas County Extension Service. For additional landscape and garden information, visit pinellascountyextension.org. For regular tips and information about what's growing in Pinellas, go to facebook.com/growpinellas.