by Sharon Morrisey, Consumer Horticulture Agent in Milwaukee County
In fall, weeds’ natural biology changes gears from growth mode to storage mode and they start moving carbohydrates into their roots for winter. By applying herbicides to weeds at this time, you trick them into doing some of the dirty work for you. They will carry the chemicals into their roots along with their carbohydrates where these products kill the plants, roots and all. Shorter days and a string of several evenings with temperatures in the 30s are the signals for plants to shirt to storage mode and for you to get out your sprayer.
Choose your weed killer carefully. Although some products can tell a dandelion from a blade of grass, they do not distinguish between that dandelion and your prized dahlia. That is why it is so difficult to use broadleaf herbicides in mixed flower and vegetable beds where the weeds and your precious plants are all broadleaves. Other herbicides kill everything green and living, dandelions, dahlias, and your lawn alike. Making this mistake for spot treating your lawn leaves dozens of little round dead spots where you sprayed.
by Ken Schroeder, Portage County UW-Extension Agriculture Agent
Wild Parsnip, Pastinaca sativa, is an invasive member of the carrot family that continues to spread into unmanaged areas throughout Wisconsin. It likes to grow in sunny, grassy areas along roadsides, railroads, and field borders but is not limited to these conditions. Primary means of spread is by seed that can be moved long distances while mowing roadsides after the plant has set seed.
What’s the concern? The biggest concern isn’t the fact that it is invasive and rapidly spreading but that it will cause burns and blistering of the skin if you come in contact with plant sap in the presence of sunlight. This is known as phytophotodermatitis. Blisters and rashes appear 24 to 48 hours after exposure. Blisters do not spread like poison ivy but are uncomfortable and may leave scars lasting for several months to two years.
How do we identify wild parsnip? The plant is a monocarpic (the plant dies after blooming) perennial and has two growth stages. The first year it produces a non-flowering leafy rosette of pinnately compound leaves with 5 to 15 leaflets. It looks a lot like celery at this stage. In the second to third year, it produces a flowering stem four to five feet tall. Stems are grooved, hollow, and have alternately arranged compound leaves with 2 – 5 pairs of opposite, sharply toothed leaflets and petioles that wrap around the stems. Flowers are flat-topped clusters (umbels) of yellow flowers 2 – 6” wide blooming in late spring to mid-summer in Wisconsin. Seed begins to form mid to late July changing from yellow-green to tan as they mature. Along with the seeds maturing the stems and leaves begin to senesce, turning tan to brown in color.
How do we manage wild parsnip? Early detection when populations are small allow for pulling or digging. Be sure to wear gloves, long sleeves, long pants, and safety glasses or face shields to avoid skin contact with the sap. One can simply cut the taproot with a shovel or spade 1 – 2” below the soil surface. With larger populations mowing is an option if done after emergence of flower heads, but before seeds enlarge. Additionally, several chemical options exist. Be sure to read and follow label directions when using chemicals. For more detailed management options see the UW-Extension wild parsnip management publication A3924-15 at the Learning Store website https://learningstore.uwex.edu/ .
What can I do as a Master Gardener to help?
- Know how to identify wild parsnip and report locations at the Wisconsin First Detectors Network website http://fyi.uwex.edu/wifdn/get-involved/report-invasive-species/. Several options are listed including a downloadable smartphone app.
- Educate others about the existence and danger of wild parsnip.
- Carry a sharp shovel or spade with you and when you see only one or a few plants consider cutting off the stems below the soil surface. As long as they haven’t gone to seed the plants can then be left to die. Check back the next year to see if additional plants emerge and cut those too. CAUTION do not do this on private property without getting permission from the property owner.
Additional invasive species information
- The University of Wisconsin Weed Science website http://fyi.uwex.edu/weedsci/ is a great resource for weed id and management info and has several short YouTube videos to help with identification.
The Wisconsin DNR invasive species website http://dnr.wi.gov/topic/Invasives/ has a wealth of information on not only terrestrial invasive species but aquatic and wetland invasives as well.
by OCMGA Master Gardener Rich Fischer
Shredded Wheat Straw
One of the things I love about master gardeners is that we are always willing to share our experience and knowledge with other gardeners. While at the last master gardener meeting someone mentioned to me that they bought bags of shredded wheat straw from Ace Hardware on Northland Avenue to use as mulch around their vegetable garden. So being the curious gardener that I am I had to check it out. I wish I could give credit to who told me this, but alas old age has affected my memory, or maybe it was too much partying in my wayward youth.
Bag of shredded wheat straw
She was so right. This shredded wheat straw is awesome. Way easier to spread around the tomato plants than any other kind of ground cover. It easily allows the water to get through and keeps down the weeds. And at the end of the gardening season no need to rake it up, just let it decompose as an organic soil amendment.
Like many vegetable growers I have tomato fungal disease carry over from year to year despite my best efforts to rotate the location. It is either early blight or Septoria leaf spot or both. The tomato plant leaves turn wilt, turn brown and die from the bottom up. But we still get enough tomatoes and the fruit is just fine. Hopefully the shredded wheat straw mulch will prevent soil splash and reduce the blight this year. I have also been cutting off and disposing the effected lower leaves at the first sign of wilt in hopes of slowing it down.
I am grateful for the information we gardeners share with one another and hope you find this gardening tip helpful.
Rich’s tomatoes before and after applying the mulch:
Thanks to OCMGA Master Gardener Mary Learman for discovering this information.
Keep an eye on your garden and your lawn. As though we didn’t have enough weeds and invasives to watch, the University of Illinois Extension warns of Pellitory (Parietaria pensylvanica) appearing in the midwest. Funnily, the leaves remind one of peony plants or, perhaps, dianthus before it blooms. Don’t be fooled, however, as it’s aggressive enough to take on your whole garden and flexible enough to grow out of cracks.
For more information, follow this link to the article published by the University of Illinois Extension.
by OCMGA Master Gardener Vicki Schilleman
Everyone wants the perfect sea of smooth green lawn with nary a hint of weed, bare spot, or discolored grass. Alas, easier said than done! However, here are 5 steps that will help create a beautiful and naturally weed-resistant lawn.
- Prepare the soil. Though they are seldom thought of that way, expanses of mown grass are actually very intensive gardens. Loose, fertile soil of the right pH is even more important for good lawns than it is for tasty tomatoes or lavishly blooming shrubs.
- Invest in the best seed, use enough of it, and plant it at the right time. The first defense against weeks is a turf that is thick enough to prevent them from getting the light they need to sprout and grow. The grass won’t be thick if you’re stingy with either quality of quantity, and it won’t fill in properly unless you give it a proper start.
- Think long term. Be sure the seed mixture comprises grasses that will be long lived, such as red fescues and bluegrasses. There should be only a very small amount of rye grass, if there is any at all. Rye grasses grow quickly, helping the lawn to look good fast and preventing the growth of some weeds. But because they are up so quickly, they steal nutrients, water, and light from slower-growing but more durable types. As a result, newly established turf has a lot of rye in it. This is fine for a short while. But even perennial rye dies out within a few years, and when it does it leaves a whole lot of room for weeds to move in. A sprinkling of rye can be used if you are the impatient type. But you’ll have better long-term weed control if you go for the slow stuff and hand-weed for the first year or so while the good grasses are settling in.
- Adjust the mower to the season. No matter what height you like your lawn, letting it get a bit shaggy in summer — a good 3 inches tall — will cut down on weeds. The taller gras provides more shade, keeping the grass roots cool and healthy while making it harder for weed seeds to sprout and find the light.
- Don’t water if there’s a drought. This may seem counterintuitive, and it isn’t entirely true: if you have an endless supply and can water the lawn thoroughly, by all means go ahead. But if water is limited, you’re much better off letter the lawn go dormant than trying to give it “just enough to stay alive.” Grasses naturally lie low and turn brown during droughts. They aren’t dead — they’re just sleeping. A small amount of water won’t be enough to keep grasses green, but it will keep the lawn green, because the watered weeds will thrive
Organic Weed & Feed
For those of us who become frustrated at the growth of weeds in our lawns when we’re using organic fertilizers, there is one help: corn gluten meal, a by-product of corn milling. It is quite high in nitrogen, which makes it a good fertilizer for grass. And it will prevent weed seeds from growing.
But — there’s always a but — that’s it. Corn gluten kills by drying up the baby sprouts as soon as the seed cracks open. It has no effect on perennial weeds (other than to encourage them) or on annual weeds that are already growing.
Furthermore, it must make good contact with the weed seeds in order to kill them, not a problem on bare soil but a tricky proposition if the grass is reasonably thick. It works best when the soil is warm, by which time many annual weeds have long since been up and about. And it lasts for only about six weeks, so you have to apply it frequently.
All that said, corn gluten is a relatively benign fertilizer, and it can help control annual weeds if you use it faithfully, from spring to fall, for a couple of years. It is nontoxic and, in home-garden quantities, safe for the environment.