How Long Does Tree Spray Need?

[Pavel314]

I've been wanting to spray my small orchard for three days now, since the petals fell, but it's been too windy. I'd hoped the wind would die down this evening, Thursday, but no luck. I'll try tomorrow evening, when I get home from work.

They're predicting thunderstorms Sunday afternoon. So if I spray Friday evening and it rains Sunday afternoon, about 40 or so hours later, will the bug spray and fungicide have had enough time to do their job before washing away? What's the minimum time needed between spray and rain?

Paul

[Thos]

What are you trying to spray, and what are you trying to control?

[Pavel314]

I'm spraying fruit trees, mainly apples, with copper fungicide and insecticide.

Paul

[David E. Ross]

You may be too late. Copper fungicide should have been sprayed just after pruning while the trees were dormant. In some cases (e.g., peaches), you should spray again just as the flower buds begin to swell and show a little color.

The copper spray that I use says that, if it rains within 48 hours after being applied, it has to be sprayed again.