Phenology Report for May 18, 2015

From time to time, we will be reporting on the development of invasive plants across Illinois, informing readers about what is in bloom, leafing out, setting seed, senescing in different regions of the state.  Feel free to add to the knowledge by emailing chris.evans@illinois.gov and letting me know what the plants are doing in your area of Illinois.

Phenology Report for May 18, 2015*

(Contributors include Mike Davis, Nick Seaton, Caleb Grantham, Eric Smith, Scott Schirmer, Cathy McGlynn, and Kathleen Garness)
*Report based upon observations between May 11-15, 2015

Southern Illinois

• Multiflora rose, Rosa multiflora and bush honeysuckle, Lonicera maackii - These two common woody shrub species are in full bloom.  Spring leaf expansion is complete and the plants are susceptible to herbicide treatments (both foliar and cut stump work at this time of year).  Since both species do attract pollinators, it is recommended that you wait until the blooms have diminished before any foliar applications of herbicide.
• Japanese honeysuckle, Lonicera japonica - this invasive plant is blooming now.  This species has a very long bloom window and can flower from now through the summer and fall, even into early winter.
• Autumn olive, Elaeagnus umbellata and Callery pear, Pyrus calleryana - These invasive shrubs/small trees are both past flowering and have small, unripe fruits.  They are both susceptible to herbicide treatments at this point in development. 
• Garlic mustard, Alliaria petiolata - This herbaceous woodland invader is nearly finished blooming and now mostly has green, unripe fruit pods.  Herbicide treatments are not effective at this developmental stage.  Instead, hand pull, bag, and remove plants.
• Sweet clover, Melilotus sp. and Sericea lespedeza, Lespedeza cuneata - both of these invasive members of the bean family are starting vigorous growth.  Sweet clover is in full flower.  Sericea lespedeza is not flowering yet but is in some place about knee high.  Look for these species growing in open areas, prairies, pastures, and roadsides.
• Japanese stiltgrass, Microstegium vimineum - this annual grass species started germinating about three weeks ago and is now several inches high.  As the temperatures increase, expect the growth rate of this plant to drastically increase.  While the plants can be easily killed at this time of year, subsequent germination can still occur.  Either plan on coming back at a later date for follow up treatments or hold off on treatments until mid-late summer.
• Poison hemlock, Conium maculatum and Wild parsnip, Pastinaca sativa - Both of these are biennial members of the carrot family.  Poison hemlock is flowering at this point and wild parsnip is just starting to come into flower.  Herbicide treatments can still be effective at this point, but watch poison hemlock and stop applying herbicides when the flowers start to turn into fruit.
• Reed Canarygrass, Phalaris arundinacea - This perennial grass species is just starting to flower.  Now is a great time of year to control this species with an herbicide application.  Keep in mind that this species often grows in wet areas.  If so, an aquatic-labelled herbicide should be used.
• Crow vetch, Securigera varia - This perennial herbaceous vine is just starting to bloom.  You can find this plant along many roadsides in the region.

Central Illinois

• Garlic mustard, Alliaria petiolata - This biennial invasive plant is in full flower right now but many are starting to show the seed pods.  While herbicides could still be effective at this point with so few seed pods, it may be more effective to hand pull, bag, and remove plants.
• Sweet clover, Melilotus sp. - is starting to bolt but is still low and "bushy" looking with no flowers yet.  This is a great time of year to treat this species, taking care to avoid non-target impacts.  UPDATE: On 5-18, Sweet clover was just starting to come into flower in this region.
• Dame's Rocket, Hesperis matronalis  - Is in full flower right now, but no seed pods have been observed yet.  As with garlic mustard, the best method of control when the plants are in full flower is to hand pull, bag, and remove all plants.
• Poison hemlock, Conium maculatum and Wild parsnip, Pastinaca sativa - both of these biennial plants are bolting but neither is flowering as of yet, though they are close.  This is the ideal time to treat them.
• Crown vetch, Securigera varia - This perennial herbaceous vine is growing quickly, but no flowers as of yet.
• Bush honeysuckle, Lonicera maackii and Autumn olive, Elaeagnus umbellata  - These woody invasive shrubs are both flowering, but no fruit formation as of yet.  Spring leaf expansion is complete and the plants are susceptible to herbicide treatments (both foliar and cut stump work at this time of year).  Since both species do attract pollinators, it is recommended that you wait until the blooms have diminished before any foliar applications of herbicide.
• Star of Bethlehem,Ornithogalum umbellatum  - This weedy low growing plant is in full flower, but is past peak.  Flowering should end soon.

Northern Illinois

• Garlic mustard, Alliaria petiolata - This biennial invasive plant is in full flower right now and just starting to develop seed pods.  While herbicides could still be effective at this point with so few seed pods, it may be more effective to hand pull, bag, and remove plants.
• Yellow rocket, Barbarea vulgaris - This weedy mustard is in full bloom now.  You can see this plant in roadsides, old fields, and other open areas.
• Canada thistle, Cirsium arvense - This perennial thistle is starting to grow but not yet near bloom.  Bull thistle, Cirsium vulgare, and teasel, Dipsacus sp., rosettes are apparent but not near blooming.
• Reed canarygrass, Phalaris arundinacea - This perennial grass is starting to mature but not in flower yet.  The best time of year to control this species with an herbicide application is just at the point of flowering.  Keep in mind that this species often grows in wet areas.  If so, an aquatic-labelled herbicide should be used.
• Common buckthorn, Rhamnus cathartica - This woody invasive shrub/small tree is fully leafed out.  Spring leaf expansion is complete and the plants are susceptible to herbicide treatments (both foliar and cut stump work at this time of year). 
• Japanese honeysuckle, Lonicera japonica - this woody invasive vine is just starting to bloom.  This species has a very long bloom window and can flower from now through the summer and fall, even into early winter.
• Bush honeysuckle, Lonicera maackii and Japanese barberry, Berberis thunbergii - These woody invasive shrubs are both in bloom right now.  Spring leaf expansion is complete and the plants are susceptible to herbicide treatments (both foliar and cut stump work at this time of year). 
• Leafy spurge, Euphorbia esula -  This herbaceous plant is in full bloom.