DS
Applying Etho before rain: How long should you wait?
Hi team I was wondering if there is any advice on how long a window of time should be before rain after applying etho as a pre-emergant?
I have a bit of light green grass in my MDR, and although I know it’s not the best time of year to apply etho I figure it’s better than not applying it at all. The problem is, every free day I get to apply it seem to have rain forcast in the afternoon. I know etho needs to be irrigated in with 3-5mm of water after application, but if there is rain a few hours after that it would get washed in even further and not be effective?
Also ill apply it as a post emergant 2 weeks later, how long would i need before rain with a post emergant application?
Why isn’t it the best time to apply Etho? Everything I’ve read recommends applying pre-emergents through winter to prevent Poa annua germination.
Rain doesn’t really matter when using Etho as a pre-emergent because you’re going to water it in anyway, provided it’s not absolutely pouring. As a post-emergent, I generally aim for 4–6 hours without rain before irrigation or rainfall.
@Lance McClure as a post emergent in winter it’s not ideal because of slowed growth and it just takes weeks to work. As a pre emergent definitely fine. What’s more important is confirming it’s actually Poa, you will still get good results when caught in the very early stages using just a pre emergent as it is root absorbed too.
@Garry B any idea on how much of a window before rain i need? Was looking to get some down today as pre emergant but with rain forcast this arvo and for days afterwards I thought I'd hold off
@David van Schreven 4-6 hours is a good rule for both pre and post emergent applications. Although not such an issue when applying as a pre emergent.
Etho's not purely a surface acting product, it works through both roots and shoot uptake as it moves through the plant. For the pre-em side, it needs to move into the top of the soil profile where it clings to organic matter, thatch and humus mostly, and that's what keeps it up in the root zone instead of leaching straight through. That's the point of watering it in, you're not trying to drive it deep, just far enough that the organic matter up top can hold it and the roots can pick it up as they grow through.
A bit of rain a few hours after you've already put your 3-5mm on isn't washing your application away, if anything it's doing more of the same job the irrigation started. What you don't want is a proper downpour before you've got any water on it at all, that's when you risk runoff, especially on a slope or if the ground's already wet.
The post-emergent application is the one where timing before rain actually matters, because you're relying on the leaf absorbing the product rather than the soil. You want the leaf dry and the product sitting on it long enough to get absorbed before anything washes it off. I'd be giving it a minimum of 4 to 6 hours before rain is forecast, longer if you can.
@Jonny Hicks thanks Jonny, very informative and detailed reply, just applied it now. Will do another post emergant application in 2 weeks.