*Report based upon observations between June 10-18, 2015
Southern Illinois
- Multiflora rose, Rosa multiflora, bush honeysuckle, Lonicera maackii, and Autumn olive, Elaeagnus umbellata- These common woody shrub species are all past bloom with green fruit that is starting to ripen. At this time the plants are susceptible to herbicide treatments (both foliar and cut stump work at this time of year).
- Garlic mustard, Alliaria petiolata - This herbaceous woodland invader is senescing and starting to drop mature seeds. Control at this time of year is not practical because of the risk to spreading seeds.
- Sweet clover, Melilotus sp. - Sweet clover, both yellow and white, are in full bloom throughout the region. Look for them along roadsides, in prairies, and other open areas
- Sericea lespedeza, Lespedeza cuneata - Sericea lespedeza is reaching its full height but not in flower yet. Look for this species growing in open areas, prairies, pastures, and roadsides. Control is effective at this point through flowering.
- Japanese stiltgrass, Microstegium vimineum - This annual grass species is starting to put on a lot of growth but will not flower until near the end of summer. Germination is likely finished for the year so treatments can begin.
- Poison hemlock, Conium maculatum - This biennial members of the carrot family is past peak on blooming. Most plants are transitioning into seed production Herbicide treatments are likely not effective at this point.
- Reed Canarygrass, Phalaris arundinacea - This perennial grass species is transitioning from flowering to mature seed. If control is desired at this time of year, the most productive method would be to mow the plants down (clean the equipment afterwards) and wait until the regrowth is 18-24" high before applying herbicide. Keep in mind that this species often grows in wet areas. If so, an aquatic-labelled herbicide should be used.
- Crown vetch, Securigera varia - This perennial herbaceous vine is in full bloom. You can find this plant along many roadsides in the region.
- Chinese yam, Dioscorea oppositifolia - This herbaceous perennial vine is growing rapidly. Look for the aerial tubers, called bulbils, to start to form at any point.
- Teasel, Dipsacus sp. - Both common and cutleaf teasel are bolting and initial flower heads forming, though no flowers have been observed yet. Now is the perfect time to treat teasel with herbicides but once flowering has started, switch to hand-pulling. Mowing or cutting the flower heads off is not effective.
- Mimosa, Albizia julibrissin, and rose of Sharon, Hibiscus syriacus - both of these shrubs/trees are starting to flower right now. Look for them along roadsides and forest edges.
- Common reed, Phragmites australis - This huge grass species is growing very fast and starting to get very tall but flower formation has not be observed yet. The best time to treat this species is right at the point of flower initiation.
- Hedgeparsley, Torilis sp. - This herbaceous member of the carrot family is just starting to bloom now. Hedgeparsley is a relatively new invader to southern Illinois but can be found along roadsides and other disturbed areas and can grow in both sun and shade environments.
- Johnsongrass, Sorghum halepense - This state Noxious Weed is just starting to come into flower. Control is most effective on populations that are almost blooming, but treatments can still be made to populations in early flowering.
Central Illinois
- Sweet clover, Melilotus sp. - Yellow sweet clover is in full bloom and white sweet clover is just starting to bloom. Look for them along roadsides, in prairies, and other open areas.
- Dame's Rocket, Hesperis matronalis - This species is past peak in blooming. While some blooms can still be observed, plants mostly have seed pods on them at this point. Mechanical control (i.e. hand pulling) can still be effective though care needs to be taken not to spread the seeds.
- Poison hemlock, Conium maculatum and Wild parsnip, Pastinaca sativa - both of these biennial plants are in bloom right now, though moving towards past peak. While treatments can still be somewhat effective the best timing is just before blooming.
- Teasel, Dipsacus sp. - Teasel is bolting right now but not forming flowers. This is the ideal time to treat teasel chemically.
- Canada thistle, Cirsium arvense - This perennial thistle is just starting to come into flower. Unlike most of the other thistles, this species can also spread via rhizomes.
- Reed canarygrass, Phalaris arundinacea - This perennial grass species seeds are starting to harden. If control is desired at this time of year, the most productive method would be to mow the plants down (clean the equipment afterwards) and wait until the regrowth is 18-24" high before applying herbicide. Keep in mind that this species often grows in wet areas. If so, an aquatic-labelled herbicide should be used.
- Crown vetch, Securigera varia and Birdsfoot trefoil, Lotus corniculatus - These two invasive members of the bean family are in full bloom. Look for them in open areas, such as roadsides and prairies.
Northern Illinois
- Wild parsnip, Pastinaca sativa - This biennial species is blooming, but past peak. Care should be taken to not expose your skin to wild parsnip sap, particularly in the presence of sunlight, as this can result in sever rashes and burns.
- Poison hemlock, Conium maculatum - This biennial invader of open lands is forming buds but not yet blooming. This is an ideal time to treat this species. Unlike wild parsnip, this species typically does not give you burns or rashes when it contacts your skin, but it is extremely poisonous if ingested.
- Multiflora rose, Rosa multiflora - This species is blooming but past peak flowering. At this time this species is susceptible to herbicide treatments (both foliar and cut stump work at this time of year)
- Bush honeysuckle, Lonicera maackii - This woody shrub is past flowering and beginning to set fruit, though the fruit are not ripe yet. At this time this species is susceptible to herbicide treatments (both foliar and cut stump work at this time of year)
- Common buckthorn, Rhamnus cathartica - This woody shrub/small tree is past blooming but fruit have not yet formed. At this time this species is susceptible to herbicide treatments (both foliar and cut stump work at this time of year)
- Crown vetch, Securigera varia and Birdsfoot trefoil, Lotus corniculatus - These two invasive members of the bean family are starting to bloom. Look for them in open areas, such as roadsides and prairies.
- Sweet clover, Melilotus sp. - Yellow sweet clover is blooming but white sweet clover has not yet started to flower. Look for them along roadsides, in prairies, and other open areas.
- Japanese knotweed, Fallopia japonica - This aggressive herbaceous perennial is blooming at this point. Even though flowers are present, seed viability is often low and this species can be effectively controlled at this point.
- Purple loosestrife, Lythrum salicaria - this wetland invader is not yet blooming. While it can be hard to spot when it is not in flower, this is a great time to treat the species. When using chemical treatments, be sure to use an herbicide approved for use in aquatic situations.
- Teasel, Dipsacus sp. - Teasel is starting to bolt right now but not forming flowers. This is the ideal time to treat teasel chemically.
- Yellow sweet flag iris, Iris pseudacorus - This invasive iris is past flowering. Because this species often grows in wetlands, be sure to use an herbicide that is approved for use in aquatic situations when treating it.
- Reed canarygrass, Phalaris arundinacea - This species is in full flower. While pre-flowering and very early flowering are the best times to treat this species, effective control can be achieved at full flower. Once the flowers start to fade, consider mowing the grass and treating the regrowth.
- Fig buttercup, Ficaria verna - This species is starting to senesce. It is too late to do any management on this species for this growing season. The early phenology of this species causes it to directly compete with many of our spring ephemeral wildflowers.
