I spray every two weeks, semi-religiously, all season long, beginning at when new spring growth after spring pruning, is up 2", then all the way to late October.
The Scott's lithium battery powered sprayer I got makes spraying less of a chore, but the sprayer is poorly designed: awkwardly balanced and prone to teeter, very heavy when full with 2 gal. of formula, about >20 lbs., and the stream is weak even with a full charge, but everyone reports this design fault who owns one.
There are only three spray settings on the nozzle, but I fiddled around and found a sweet spot that's satisfactory. The pressure needed to force out a decent spray from the nozzle causes the hose that attaches to the tank and spray wand to become stiff, creating mobility issues, increasing the risk of the tank teetering over. One full battery charge will last 2 sprayings for me, but barely last for 3 sprayings. The battery is encased inside a removable pump/pressurizing unit, fastened by screwing it into the top of the tank.
I still say that the Scott's Lithium Sprayer is decently usable, but not well designed.
Rifis, may you be the first to know that after more years than I can count right now, this past season, 2025, has unexpectantly and hopefully finally, been Rose Midge Fly FREE!!! I still can hardly believe my good fortune......a true blessing from above. You know the unrelenting dilemma I faced, year after year.
Somehow, the population both in my garden and evidently from the transient RMFs from the neighborhood have completely vanished. I did add Bayer Complete Insect killer, 1 tbl./gal. water, every spray session (mostly concentrating on black spot control), all summer long anyway, because you are probably aware that even with diligent spraying, a bad RMF infestation only means 90% control. Without fail, there will be damaged tips after every spray session, even with diligent spraying. The RMF is that insidious.
Not one single damaged growing tip was encountered all season long. I believe now that I could have dispensed with spraying for Rose Midge Fly by early August if I dared.
I have always included Bayer Complete Insect Killer along with fungicide in my spray mix. I just have to remember to add only 1 tablespoon per gallon of water of the insecticide, while both the Bayer and the Spectricide fungicide require 2 tablespoons of fungicide per gallon of water. It's easy to forget/confuse which gets what.
I alternate fungicides whenever I get to the end of a bottle. Then I switch to the other fungicide until that bottle runs out. This way the contents of a new, fresh bottle are always being used for a current spray session. When I am just about running out of one fungicide, I order the other brand in.
Spectricide Immunox comes only in a 16 oz./pint bottle. $16.99 is Amazon's current price. It's active ingredient, myclobutanil, 1.55%, is a thin, obnoxious smelling, maple syrup colored liquid. Your just sprayed roses will be smelly for a day or so, no more. 2 tablespoons per gallon of water is the recommended dilution rate. Once dry upon the foliage, it cannot be washed off. I only spray the leaf upper surfaces, but do so thoroughly. Immunox is not a systemic fungicide. It kills and prevents leaf surface located fungi. It is not absorbed into the rose's leaves. Every two week sprayings are recommended, which is my program, with occasional, unavoidable additional days per session.
Bayer Bio-Advanced Disease Control for Roses, Flowers and Shrubs, 32 oz./quart bottle. $12.09 is Amazon's current price. The active ingredient is Tebuconazole, 2.90%. It's absorbed systemically. There is no discernable odor to the sprayed foliage. The lightly thick, off-white colored liquid fungicide, is administered 2 tablespoons per gallon of water. When sprayed and the foliage surface becomes dry, it will not wash off. It is rainproof.
When combatting a fungus infection that has not previously been sprayed with a fungicide, spraying every week for a while, should get the infection under control. Every two week sprayings can begin thereafter.
Hope this helps.
Moses.
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