In order to possibily discourage RRD, when is the best time to spray wilt proof? Won't the rain wash it away?
I have never heard of this - what is the theory?
The theory is that the airborne mites will not recognize the leaves as rose leaves so they will choose to move on.
This was inspired by the mites being unwilling to stay on leaves of R. bracteata in laboratory experiments.
At least two rose growers in the central and eastern US have had lower RRD infection rates than they might have had otherwise possibly because of their use of antitranspirant sprays.
To try to answer Lainey's question, I'd need to know where Lainey lives. IF in east Tennessee, I'd start spraying antitranspirants in mid May, or if this heat hold, next week. Midsummer, if temps are above 70s at night, probably not, and then again in August September and maybe into October. This comes with no guarantees. But there is some logic behind it. The problem is, that conditions (local temps, temps in upwind areas where the mites are established, future winds) do vary continually.
This is an attempt to reduce disease pressure on a garden and it has some limited success.
Thank you, anntn,
Actually my zone has changed to 7a, I'm in SW VA. So if night temperatures are above 70, don't spray wilt proof. If that correct?