Another Weed Question

I volunteer spray a couple back-country weed patches for the Forest Service. Last night I was in the Spanish Peaks at a Yellow Toadflax patch I've been treating since 2016. The toadflax is about gone, but in its place are a couple of tall grasses that look out of place.

The first grass has heads about 4' high. It looks vaguely familiar...









The heads on the second grass were about 5' high. The heads were fuzzy looking and probably 5-6" long. They were full of those sharp seeds.




What are these grasses?


As an aside, I did an interesting experiment with this toadflax patch. When I first sprayed it in 2016 it was a lot denser than I originally planned for and I didn't have enough tordon/2-4d mix. Being curious, I put a log down the center of the patch and sprayed everything on south side. On the north side of the log I pulled the larger plants and sprayed what was left.

As you can guess, the side I sprayed heavily is the side with the tall, out of place grasses. The side where I pulled the majority of plants has what appears to be the local native "grass" (it sort of looks like bear grass without the flowering stems). Both sides had roughly the same amount of toadflax, which was greatly reduced since 2016 (virtually gone).

In this case, pulling the mature plants and spraying what was left was just as effective as spraying everything. However, the collateral damage was significantly less.

First looks like western wheatgrass, maybe... https://plants.usda.gov/core/profile?symbol=pasm

Second looks like needle and thread grass. https://plants.usda.gov/core/profile?symbol=HECOC8

First is hard to tell, but does look like some kind of wheatgrass.

Second is not needle and thread- awns too short, head too dense and overall too tall. Looks very similar to green needlegrass though, and that’s a very widespread native western grass.


http://fieldguide.mt.gov/speciesDetail.aspx?elcode=PMPOA4B090

Hunting Wife said:

First is hard to tell, but does look like some kind of wheatgrass.

Second is not needle and thread- awns too short, head too dense and overall too tall. Looks very similar to green needlegrass though, and that’s a very widespread native western grass.


http://fieldguide.mt.gov/speciesDetail.aspx?elcode=PMPOA4B090

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I could agree on #2 and am of the same thought on #1. Not enough in the pics to get to species, but appears to be a wheatgrass.

Which makes me want to ask the OP about their definition of "collateral damage". By the description, I could argue that the heavily sprayed side is "better"...

First looks like Bromegrass.

Agree on green needle or similar for #2. My gut was mountain brome (BRMA4) on #1 but I'm not certain by any means, the heads are shattered enough it's kinda hard to see what's what. In one of the overall pictures there appears to be a stipa, brome, and an elymus. I've been working tall forb sites this summer so I'm semi dialed on purty flowers, but haven't counted much grass over 10" precip since last year. In meadows like that the elymus I most commonly see is trachycaulus, slender wheatgrass, but western pops up for sure.

Where's Grant?

1_pointer said:

Which makes me want to ask the OP about their definition of "collateral damage". By the description, I could argue that the heavily sprayed side is "better"...

Click to expand...

Good question, especially if the new grasses are native. However, after two years the pulled side was very similar to the surrounding area, which you could say is also the control area. Whereas the heavily sprayed side was dramatically different.

This is what the 15' diameter patch looked like in 2016 AFTER I pulled the taller toadflax on the left side of the log. I then sprayed the remaining plants on both sides.



Here is the area from the same viewpoint on Wednesday. The light and contrast are poor, but the right side is full of the two bunchgrasses I asked about.


Here it is looking from the other direction.



Now which side is "better" depends on your mission, but what I found interesting is that after two years the density of toadflax was about the same on either side.

Hunting Wife said:

First is hard to tell, but does look like some kind of wheatgrass.

Second is not needle and thread- awns too short, head too dense and overall too tall. Looks very similar to green needlegrass though, and that’s a very widespread native western grass.


http://fieldguide.mt.gov/speciesDetail.aspx?elcode=PMPOA4B090

Click to expand...

That green needlegrass looks pretty similar, although the tips were 5' off the ground which is quite a bit taller than the 3' height they give.

I take it neither grass is something to worry about...

Green needle is pretty common on my veg plots, and it is often in that 3 foot range. But I've seen it in both prairie reconstructions and in areas with good moisture get near shoulder height on me, and occasionally taller - I'm 5'4". Not sure if there are different varieties....maybe pointer knows?

Just out of curiosity, do you know what grasses are on the other half of your site?

Hunting Wife said:

Green needle is pretty common on my veg plots, and it is often in that 3 foot range. But I've seen it in both prairie reconstructions and in areas with good moisture get near shoulder height on me, and occasionally taller - I'm 5'4". Not sure if there are different varieties....maybe pointer knows?

Just out of curiosity, do you know what grasses are on the other half of your site?

Click to expand...

I don't know the grasses/sedges very well since they are so hard to ID from pictures. The altitude is 7500' in lodgepole and they were what I usually see in that country.

I've never noticed that particular needlegrass before, but now I'll probably see it everywhere. The wheatgrass was present in the meadow, but very scattered.

No clue on varieties of green needle.

Rob- Thanks for getting my point and not being offended. The presence of the noxious weed makes me wonder if your control is not a depleted state? Either way, kudos for helping with the weed control.

1_pointer said:

No clue on varieties of green needle.

Rob- Thanks for getting my point and not being offended. The presence of the noxious weed makes me wonder if your control is not a depleted state? Either way, kudos for helping with the weed control.

Click to expand...

The area is just south of the Flying D, and I'm sure it was was grazed at one time.

The toadflax was an isolated patch on a mostly abandoned trail. It was such an anomaly that I reported it to the USFS and offered to treat it before it spread. I had imagined that the patch started when a horseman spread some contaminated hay and wondered if these other grasses weren't also invaders, but it doesn't sound like they were. I talked with the manager of the Flying D and he said they do have toadflax problems down lower.

It’s hard to tell from the phot, but the stuff with the appears to be green needle grass almost looks like blue bunch wheatgrass with those funny bent awns. Sometimes when it is fully ripe it looks almost fuzzy like that, but it’s hard to tell whether it’s a bunchgrass or not without a photo of the base. Regardless, good job spraying and pulling, that is a job well done. Toadflax is notoriously hard to kill by spraying, especially without nuking the area. However, that’s a pretty weird place for toadflax, pretty wet, so maybe the grass did better. Good job and good f it’s not cheatgrass you don’t have anything to worry about in terms of grasses that I know of.