Nearly 15 years ago I did major switchgrass seeding and tree planting, and doing so led to an unexpected result where two overlapped.
I had of course killed ALL the sod the fall before and winter seeded the switchgrass well ahead of the tree planting, so no surprise that I planted a little to far into the area where the trees eventually would end up being planted.
The tree plantings were sprayed with Oust herbicide and weed control was perfect! No other herbicide impresses me with such awesome residual effect with the exception of atrazine applied at higher rates.
This is what the switchgrass looked like in the rows band sprayed with Oust the
first fall!
Where I had not used any herbicide there was not a switch plant to be seen the first year, held back by weed growth and clipping.
At the time both atrazine and Oust were restricted use pesticides and Oust was extremely expensive and only available in large containers costing $600-700, so buying more was out of the question for me.
Years passed by and I found a source for Oust XP (Townsend Chemical) who would sell it by the ounce and since it was not restricted in other states, I had it shipped to a friend and then back to me so I could use it on tree plantings again.
Once again the fact that switchgrass and big bluestem are impervious to Oust XP became apparent as I sprayed new tree plantings this spring where switch and big blue existed to some extent.
It's a little difficult to see in these pics, but the switchgrass plants are thriving in the band sprayed areas
Oust is now down to $5.50 an ounce and one needs 1-4 ounces per acre and at the moment is no longer restricted in Iowa making it more affordable and easier to obtain then atrazine.
Switchgrass just does not compete well with other plants when it's young, but released from that and given the freedom to grow it will flourish!
These pics are from a friends place where the exact same thing occured as happend to me 15 years ago. I broadcasted the switch seed in Febuary and again, seeded into an area where trees ended up being planted a few months later.
Oust has long acting residual effects and I took these pics while mowing in the tree planting the other day.
I had mowed this a few weeks earlier but you can see the switch plants in the narrow band sprayed area
Oust is NOT labeled for switchgrass so I'm going to test some different rates and see how new seedings handle it and release some areas that have become overgrown with goldenrod and blackberries.
Oust will kill most plants (including trees) when sprayed post emergence so it's not something one wants to spray after switchgrass emerges. Most of my tree planting sprayings where done in late April to early May when switch may have been growing but I wasn't aware of it.
So far anything I have sprayed Oust on post emergence has...died...
I frost seeded this switchgrass in a waterway last year so this is second year growth and you can really see the brome on either side, already gone to seed while the switch is lush and green in the middle of July!
Situations like these however are difficult to keep the brome from creeping back in and will require burning and some heribide use along the edges .
I tilled the rows between the trees in a tree planting where switchgrass existed, waited for grass and weeds to emerge and then nuked it all with roundup.
I went back yesterday to till it an plant it and found it full of switchgrass!
Roundup will sure kill switchgrass but apparantly it had not emerged yet? Dunno, but it sure seemed to be doing fine and I'm sure that re-tilling didn't hurt it much...
When I kill some sod this fall to prepare for frost seeding switchgrass I'll use some Oust also at that time to take advantage of it's strong residual effects and make certain that it does not effect the germinating switchgrass in anyway.....stay tuned...
