Weed Identification

Luqi Li Author

08/02/2020 Added

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Eric Chestnut and Luqi Li Weed Identification

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[00:00:02.459](upbeat music)
[00:00:20.594]Hello, I'm Dr. Luqi Li. I'm a post-doc.
[00:00:24.410]Today, me and Eric Chestnut will talk about herb grass
[00:00:28.110]and weed identification.
[00:00:30.150]We'll first talk about weed ID and our weed garden here,
[00:00:34.230]and there will be separate video
[00:00:35.760]to talk about turf grass identification.
[00:00:39.970]Here at the weed garden,
[00:00:41.800]and we'll first look at some grassy weed.
[00:00:47.770]This is large crabgrass, or called hairy crabgrass.
[00:00:52.095]Large crabgrass is a summer annual grass.
[00:00:55.340]It has a prostrate growth habit,
[00:00:58.380]and the plant killer in summer.
[00:01:01.320]Large crabgrass leaf blade and sheathes are hairy.
[00:01:07.530]Its seed head is digitate,
[00:01:10.330]with three to five finger-like spikes.
[00:01:14.826]Large crabgrass tolerates a range of conditions,
[00:01:18.120]and it is found almost anywhere.
[00:01:26.695]This is goosegrass.
[00:01:28.143]Goosegrass is a summer annual grass,
[00:01:30.600]and is sometimes confused with crabgrass.
[00:01:34.520]Goosegrass has a seed head digitate,
[00:01:37.310]with three to eight finger-like spikes.
[00:01:40.090]However, unlike crabgrass, the goosegrass seed are flatter
[00:01:44.270]and arranged in two rows like a zipper.
[00:01:48.780]Another key characteristic to identify goosegrass
[00:01:52.320]is that goosegrass sheathes are compressed
[00:01:57.100]with a light green to white color at its base.
[00:02:00.900]This white color base can be used as a key
[00:02:03.770]to differentiate goosegrass from crabgrass.
[00:02:07.187]Goosegrass tolerates close mowing,
[00:02:10.020]and often found in compact soils.
[00:02:15.590]This is barnyardgrass.
[00:02:17.326]Barnyardgrass is a summer annual grass
[00:02:19.850]with prostate growth habit in turf,
[00:02:22.410]but erect when are mown.
[00:02:24.820]Barnyardgrass has smooth leaf blades.
[00:02:27.957]The midriff on leaf is distinct.
[00:02:31.102]Barnyardgrass seed head is branched,
[00:02:33.890]and seeds are with or without (indistinct),
[00:02:36.840]are usually found in moist soils,
[00:02:39.570]often found in turf near agriculture areas.
[00:02:46.490]This is yellow foxtail.
[00:02:48.120]Yellow foxtail is a summer annual grass
[00:02:50.780]with bunch type growth habit.
[00:02:53.018]Its leaves are row and bud.
[00:02:55.671]The leaf blades have several long hairs
[00:02:58.610]at the base of the upper leaf surface.
[00:03:01.614]It has foxtail seed heads, hence its name.
[00:03:05.040]Yellow foxtail are found in pastures, roadsides, and turf.
[00:03:11.980]It tolerates close mowing.
[00:03:22.000]Next weed we have green foxtail.
[00:03:24.430]Green foxtail is also a summer annual grass
[00:03:26.900]with bunch type growth habit.
[00:03:29.024]Similarly, the leaves are row in bud.
[00:03:32.230]And the key difference between green and yellow foxtail
[00:03:35.980]is that green foxtail's leaf blade does not have hairs.
[00:03:41.007]They are often found, just like yellow foxtail,
[00:03:45.429]in pastures, roadsides, and turf.
[00:03:52.520]This is yellow nutsedge.
[00:03:54.470]Yellow nutsedge is a perennial, grasslike weed.
[00:03:58.080]However, yellow nutsedge is not grass,
[00:04:00.730]but a member of the sedge family.
[00:04:03.250]Unlike grass, sedges such as yellow nutsedge
[00:04:06.820]has three ridged yellow-green waxy leaves.
[00:04:10.700]Yellow nutsedge has a triangular stem,
[00:04:14.140]give rise to yellow colored seed head.
[00:04:17.410]Yellow nutsedge is a perennial that reproducing primarily
[00:04:21.030]by tubers that forms at the apical end of its rhizome.
[00:04:26.650]The vegetative part of the plant dies with first frost,
[00:04:30.476]but the viable tubers may remain dormant in the soil
[00:04:34.160]for years, and can sprout repeatedly in the spring.
[00:04:38.880]Yellow nutsedge are found in full sun areas.
[00:04:42.330]It favors moist soil but also grows on well-drained sites.
[00:04:53.110]And now we're gonna move on to broadleaf weeds.
[00:05:01.356]First we have common lambsquarters.
[00:05:04.520]Common lambsquarter is a summer annual broadleaf.
[00:05:07.750]Its leaves are alternately arranged.
[00:05:10.350]The leaves are tubed and are shaped like arrowheads.
[00:05:14.270]Common lambsquarter is mostly found in agronomy fields,
[00:05:17.120]but it can also show up in turf in bare areas,
[00:05:21.250]and it's pretty easily controlled
[00:05:23.050]by most broadleaf herbicides.
[00:05:28.140]Next up we have white clover.
[00:05:30.360]White clover is a perennial broadleaf.
[00:05:33.252]It has a trifoliate leaf arrangement
[00:05:35.990]with a short petiole on each leaf.
[00:05:39.030]The leaves are heart-shaped and have white markings
[00:05:41.900]in the center that form a circle
[00:05:43.620]when the three leaves are combined.
[00:05:45.862]And white clover thrives in low fertility areas
[00:05:49.910]and tolerates low mowing heights.
[00:05:57.158]This is dandelion.
[00:05:59.260]Dandelion is also a perennial broadleaf.
[00:06:02.134]It has leaves that are pointed at the tip
[00:06:04.650]and has a toothed appearance that goes down
[00:06:07.200]to the base of the plant.
[00:06:08.840]It produces a bright yellow flower that forms
[00:06:11.580]into a white, spherical seed head.
[00:06:18.043]This is prostrate knotweed.
[00:06:20.724]Prostrate knotweed is a summer annual.
[00:06:23.760]It has branched stems that spread laterally.
[00:06:27.210]The leaves are alternately arranged,
[00:06:30.320]and it has an ocrea, which is a membranous sheath,
[00:06:34.030]at the stem of the branches that can make it
[00:06:37.539]kind of difficult to control,
[00:06:40.015]and this weed in particular prefers compacted soils,
[00:06:43.830]so it's usually found near sidewalks
[00:06:46.240]and compacted areas such as that.
[00:06:54.342]Next up we have ground ivy,
[00:06:56.770]which can also be called creeping Charlie.
[00:06:59.550]It's a perennial broadleaf.
[00:07:01.685]It has kidney-shaped leaves
[00:07:03.942]with rounded ridges on the edges of the leaf.
[00:07:07.810]It's in the mint family, so therefore it has square stems.
[00:07:12.044]This plants is aggressively stoloniferous
[00:07:14.970]and can spread very rapidly, and it prefers shaded,
[00:07:19.350]moist areas, but it can also adapt to many, many habitats.
[00:07:30.125]This is wild violet, which can also be known
[00:07:33.230]as common blue violet.
[00:07:35.210]It is a perennial broadleaf.
[00:07:37.430]It has shiny, heart-shaped leaves
[00:07:40.218]that roll in towards the stem at the base.
[00:07:44.060]It can be propagated by rhizomes or seeds.
[00:07:47.790]Being wild violet,
[00:07:49.170]it has the typical violet-like purple flowers,
[00:07:52.514]and it prefers thin shaded turf areas.
[00:08:00.442]Next up is yellow wood sorrel, or yellow oxalis.
[00:08:05.649]Yellow wood sorrel can be a perennial
[00:08:08.420]or a summer annual broadleaf.
[00:08:10.938]It has trifoliate, heart-shaped leaves
[00:08:13.770]and can look pretty similar to clover.
[00:08:17.090]It has small, yellow flowers that each have five petals,
[00:08:21.027]and those yellow pods that you see can open
[00:08:24.900]and eject seeds into the surrounding areas,
[00:08:28.260]and it can be found in many habitats.
[00:08:36.540]This is common purslane. It is a summer annual broadleaf.
[00:08:40.870]It has a prostrate growth habit that forms into thick mats.
[00:08:45.210]It has thick, waxy leaves and stems
[00:08:48.210]and small yellow flowers,
[00:08:50.910]and it prefers turf areas that are thin.
[00:08:58.907]This is puncturevine.
[00:09:00.200]Puncturevine is a summer annual broadleaf.
[00:09:04.020]Like purslane, it has a low, prostrate growth habit.
[00:09:08.020]It has an even-pinnate leaf arrangement.
[00:09:11.090]It produces numerous burrs that have sharp spines,
[00:09:14.482]hence the name puncturevine.
[00:09:16.870]It has small yellow flowers,
[00:09:19.180]and it prefers sandy and compacted soil areas.
[00:09:28.740]Next we have spotted spurge.
[00:09:30.800]Spotted spurge is a summer annual broadleaf.
[00:09:33.890]It has an opposite leaf structure,
[00:09:35.950]and the leaves have a maroon blotch in the middle,
[00:09:39.250]hence the name spotted spurge.
[00:09:41.710]The stems are very hairy,
[00:09:43.780]and when snapped, they excrete a white, milky sap.
[00:09:48.060]It has small white flowers
[00:09:49.940]and prefers any thinned turf area.
[00:09:58.290]This is field bindweed. It is a perennial broadleaf.
[00:10:02.320]It has smooth arrowhead-shaped leaves,
[00:10:05.010]and it has the circular white or pink flowers
[00:10:08.610]that you can see on this sample.
[00:10:10.700]It spreads via rhizomes underground
[00:10:13.340]and also has aggressive above-ground vines,
[00:10:16.800]and it prefers dry soils.
[00:10:24.440]Next is broadleaf plantain. It's a perennial broadleaf.
[00:10:29.060]It has rosette leaf pattern.
[00:10:31.160]It has wide, oval, waxy leaves
[00:10:34.040]that are connected to the crown by a thin stem.
[00:10:37.360]Seeds mostly come from the flower stalks
[00:10:40.350]that you can see very well in this example,
[00:10:44.170]and it prefers moist soil conditions.
[00:10:50.530]This is common ragweed. It is a summer annual broadleaf.
[00:10:54.756]It has these fernlike leaves that you see here,
[00:10:58.634]and an upright stem that's covered in hairs.
[00:11:02.130]It has small green flowers that are often hard to see,
[00:11:06.314]and it's mostly found in agricultural fields,
[00:11:09.900]because it prefers heavy, moist soils.
[00:11:16.000]This is velvetleaf. Velvetleaf is a summer annual broadleaf.
[00:11:20.670]It has heart-shaped leaves with a pointy tip,
[00:11:23.550]and they feel, as the name implies, like velvet,
[00:11:26.901]and even though these are not often found in turf,
[00:11:30.870]it can be found on some roadsides.
[00:11:35.076](upbeat music)

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