Recommended Spray Programs
As soon as you receive your pesticide, write the date on the label. If properly stored in a climate-controlled area, the product should be good for 3 to 5 years (depending on the product) once opened.
Remember to always wear protective clothing and a pesticide respirator when spraying any pesticide.
With any good spray program, the key is "Prevention". You don't want to be spending all your time fighting blackspot and powdery mildew. You want to prevent it from happening in the first place.
When you prune in the spring, you should immediately start your spray program. We recommend you spray the canes and the bed with a blackspot contact-killer such as Mancozeb or Pentahlon DF (Note: these are the same chemical so use one not both). This will eliminate any black spot spores that may have wintered over.
One week later, start your preventative program and continue until your roses go dormant from cold weather. Rosarians in warmer climates like Florida and California may need to continue their spray program year round.
Our Best Program
If you have a large garden (100+ bushes) or if money is no object when it comes to protecting your prized roses, we recommend alternating the chemical "propiconazole" (Honor Guard, Banner Maxx II or Quali Pro) with either Heritage or Compass every two weeks.
Spray Honor Guard every two weeks. Add Penthalon DF or Mancozeb to the Honor Guard every other spraying. The Pentathlon DF or Mancozeb will kill any blackspot spores that are building up a resistance to the Honor Guard. Anytime you combine products, always use them at full strength.
If blackspot is already active in your garden, spraying a preventative alone is not going to be enough. You need a blackspot contact killer. Spray Pentathlon DF or Mancozeb every three days for three applications. Example: Spray on Monday, Thursday and Sunday. Spray the top and bottom side of the leaves and the bed. This will kill all the active spores and give you a fresh start. Once completed, go back to your regular preventative program.
If you are using products like Cleary's or Immunox, you will need to spray every seven days. These are excellent products but they do not give long protection like Honor Guard, Compass or Heritage.
Insecticides & Miticides
We do not recommend spraying insecticides or miticides preventively. Spray them only when you have a pest problem. Products like Orthene work great on most common pests like aphids and thrips. However, they also kill the beneficial insects that naturally keep the spider mites under control.
For best protection against aphids or Japanese beetles, we recommend Merit or Talstar. For best thrip control, use Conserve SC or AzaMax. Spray for spider mites when you first start to see evidence of them. Remember that Avid miticide only kills the adults so you will need to repeat after three or four days to kill the newly hatched mites. Floramite, Shuttle SC, and Forbid will eliminate both the adult mites and the eggs so it is rare to have to repeat more often than 21 days.
We strongly recommend the use of Indicate 5 with all of the products mentioned above. Indicate 5 is a spreader-sticker that will enable the spray to easily coat the entire upper and lower surfaces of the leaves an help the pesticide to "stick" to the plant.
All products mentioned in this article are available from Rosemania at www.rosemania.com.