Number 5 - May 23, 2016

What is That Yellow-Flowered ? duced tillage conservation practices, butterweed has become more prevalent The springtime color scheme provided in areas devoted to agronomic crop pro- by winter annual weed species in many duction. no-till fields has shifted from the hearty purple of flowering henbit and purple Butterweed completes its life cycle with- deadnettle to the bright yellow flowers in one year (an annual growth habit). of two species. Yellow rocket and cress- Field research was conducted from fall leaf groundsel (a.k.a. butterweed) both 2004 through spring 2006 at the Uni- produce bright yellow flowers and are versity of to determine the common across much of the southern emergence timing and growth charac- half of Illinois. Although flower color is teristics of butterweed in no-till fields. similar, the are distinct species. Butterweed emergence was predomi- Most of the yellow-flowered plants cur- nately during the fall months and was rently in fields is butterweed. essentially completed by November, alt- hough some emergence occurred in the Native to the United States, butterweed spring. From these results, we generally ( glabella) can be found from consider butterweed to be a winter an- east to , northward along nual species. the Atlantic coast to Virginia, and west to . Herbarium specimens Following emergence, the formation of from the Illinois Natural History Survey rosettes occurs prior to overwintering. indicate that butterweed specimens The rosette leaves have petioles that were collected in Illinois as early as connect the leaves to the stem. Often 1932. The earliest herbarium speci- the under side of the rosette leaves are mens of butterweed generally originat- deep purple. Bolting (stem elongation), ed from counties in southern Illinois. flowering and seed production occurs During the 1980s and 90s, the Illinois the following spring, often during late Natural History Survey augmented their April to early May. The stem of butter- collection with specimens from more weed is glaborous and hollow. After northern counties, such as Champaign bolting, petioles are absent from leaves and Vermillion. While scouting fields in on the upper part of the plant. The Kankakee County recently, butterweed leaves are pubescent, generally irregular was easy to find. Typically favoring in shape, and are deeply cut to the mid- moist to saturated soils, butterweed rib. The elongated stem often has a pur- thrives in areas such as wastelands, pas- plish tint. A member of the tures, fence-rows, and roadsides. With family, butterweed produces two types the increased adoption of no-till and re- of composite flowers. The outside por- tion of the flower contains ray florets during springs with prolonged, cold while the center part contains disk flo- temperatures that extend dormancy and rets. The flowers are bright yellow and allow the pathogen additional time to grouped in clusters that are located on colonize bark and bud tissues. several flowering stalks of the plant. Seeds are easily disseminated via wind Shoot blight describes the rapid death to due to the white hairs (pappus) on the newly expanding shoots and leaves. apex of the achene. Shoot blight occurs either as the patho- gen infects and kills the branch on which Yellow rocket (Barbarea vulgaris) is a a new shoot was developing or as the winter annual species in the mustard pathogen enters succulent new growth. (Brassicaceae) plant family. The plant This phase often occurs during cold can produce numerous stems that grow spring weather and can be confused from a basal crown surrounded by a ro- with frost injury. sette of deeply green leaves. These basal leaves range in length from approxi- The leaf blight phase develops from fun- mately 2–8 inches and have a large ter- gal spores produced on cankers. Infec- minal lobe that is somewhat heart- tions are most severe on the inner por- shaped at its base. Stem leaves are ar- tions of lower branches where moisture ranged alternately and become progres- remains the longest. Infected leaves de- sively shorter toward the top of the velop brown lesions along the primary plant. Flowers are produced on spike- veins. As the fungus kills the primary like racemes and consist of four petals veins, larger brown leaf areas die. The that form a cross. Seed pods (siliques) infection continues down the petiole and are about 1 inch long and nearly square into the main shoots where it overwin- in cross section. (Aaron Hager) ters. Premature defoliation is common.

Cool moist weather during the two Sycamore Anthracnose weeks following bud break favors both shoot blight and leaf blight phases. Seri- Recent weather has provided ideal con- ous infections are more likely to occur ditions for anthracnose diseases of when the average temperature is be- shade trees. Sycamores are the most tween 50° and 55°F. In contrast, syca- commonly affected trees in Illinois. more anthracnose infections are mini- mal if the average temperature is above Sycamore Anthracnose occurs in three 60°F. phases: canker, shoot blight, and leaf blight. The canker phase occurs in April In general, anthracnose diseases do not and early May while the tree is dormant. kill trees; but repeated infections can This phase kills either individual buds or weaken trees, making them susceptible the tips of year-old shoots. Girdling can- to other problems. Some defoliation may kers form just below the buds often kill- occur, but new leaves will emerge in ing them before the end of dormancy. warmer weather. Focus efforts on boost- Cankers can continue to enlarge, encir- ing tree vitality. Prune in and around the cle and kill small shoots. The canker tree to open it to better air movement. phase can be quite damaging, especially Remove dead or dying branches. Water in periods of drought. Fertilize affected can affect all above-ground parts of the trees in the fall. plant; symptoms are most often found on leaves and buds. Botrytis blight on London planetree (Platanus x acerifolia) peony causes reddish-purple spots on is a cross between the anthracnose sus- leaves and shriveled, discolored buds. ceptible Sycamore (Platanus occidental- Stems and flower petals may also be- is) and the anthracnose resistant Orien- come discolored, wilted, or shriveled. tal Planetree (Platanus orientalis). Brown or gray fuzzy masses may be ‘Columbia’, ‘Liberty,’ Exclamation!™ seen on the surface of affected tissue ('Morton Circle'), Ovation™ ('Morton with a hand lens; these are dense thick- Euclid') are several cultivars of London ets of spores produced by the fungus, planetree that exhibit resistant to an- which will blow or splash away to initi- thracnose. ate new infections. This disease is fa- vored by cloudy, rainy weather, and Unless anthracnose fungi have repeated- usually shows up in spring or early ly hit a tree or a very young tree is in- summer. volved, we do not recommend using fungicides. Additionally, treatment may Measles, or red blotch or leaf blotch, is not practical for larger trees. Trunk in- sometimes confused with Botrytis jected fungicides are available and may blight. Measles is also caused by a fungal be an option for high-value sycamore pathogen (Cladosporium paeoniae) and trees. (Travis Cleveland) symptoms are superficially similar. Ini- tial infection causes small, reddish spots on the leaves and stems, which may ex- Peony Problems pand and coalesce to form large, irregu- lar reddish-purple blotches. Warm, wet So far, it’s been a beautiful year for peo- weather favors this disease, and like Bo- nies. The tree peonies bloomed earlier, trytis blight, it usually shows up in and the herbaceous peonies are starting spring or early summer. to open. While it’s easy to enjoy these lovely plants while they’re flowering, Peony powdery mildew usually shows they’re also easy to forget about later in up later in summer. It’s a common dis- the year when the colorful blossoms are ease found on a wide variety of plants. gone, and all that’s left are the leaves. While the fungal pathogens that cause powdery mildew on various hosts are Peonies get a number of foliar diseases related, they’re not the same species. in summer and fall. The most common in Each species is fairly host-specific, so the Illinois are Botrytis blight, measles (aka powdery mildew pathogen affecting red blotch or leaf blotch), and powdery your oak tree is unlikely to cause disease mildew. to your phlox or bee balm. Powdery mil- dew can affect both leaves and stems, Botrytis blight is caused by a few related producing a white film over the surface species of the fungus Botrytis, including of the plant tissue that can be smudged B. cinerea. B. cinerea has a very wide off with fingers. As the infection pro- host range and may infect a large num- gresses, fruiting structures are produced ber of ornamental plants. Botrytis blight that can be seen with the naked eye. They appear as tiny black specks in the of loose soil mediums to raise moss gar- white film. dens on rocks and boulders, spraying them daily with moisture. Books have None of these diseases are considered a been written on developing your own threat to an otherwise healthy plant, but moss garden. they can drastically reduce aesthetic ap- peal. Rarely, on plants that are heavily On the other hand, more people get frus- stressed due to other pest pressures or trated with moss taking over their poor environmental conditions, these lawns, choking out the turfgrass. diseases can be lethal. Happily, man- agement of all of these pathogens is fair- Moss is classified as a bryophyte, one of ly straight-forward. simplest forms of plants. They absorb water and nutrients through their leaves. Cultural management practices include They differ from most of our typical planting peonies appropriately by avoid- weeds in that they reproduce by spores ing heavily shaded areas and spacing instead of seeds, and don’t have a vascu- plants to avoid over-crowding. Watering lar system – the xylem, cambium and at the base of the plants and early in the phloem we learned in elementary school. day can also help reduce some disease Not having the vascular system means issues. Most importantly, good sanita- that food and water flow freely within tion should be practiced. Spent blooms the plant. It also means the plant doesn’t should be cut from plants, infected have the ability to produce tall stems, leaves and stems removed, and all with plant growth just bunched on top of above-ground plant tissue cut and re- each other creating a layered effect. moved in autumn when the plants begin to senesce. Moss prefers a loose growing medium which is why you find it growing on the Fungicides are available and can be sand between brick and stone pavers, on helpful to suppress heavy infestations, shake shingles, and on rock scree under but are rarely needed most years. Cop- trees in foggy, tree-lined mountains. per, copper + mancozeb, copper hy- However, moss will grow on the thatch, drozide, copper sulfate, and mancozeb organic layer, sitting on top of a poorly- are labeled for use against Botrytis drained clay soil. blight and measles; neem oil, potassium bicarbonate, sulfur, tebuconazole, and Moss is generally an indicator of site triticonazole are labeled for use against condition problems. Fix those condi- powdery mildews. (Diane Plewa) tions, and the moss problems usually subside, though they may not be totally gone. Just killing the moss without Moss changing the site conditions will only al- low moss to re-grow. Conditions favor- Some folks spend time and money mix- ing moss generally don’t favor turfgrass. ing up concoctions to get moss to grow between bricks and stone pavers in Moss thrives in shade and moisture, sidewalks and patios. Others fills con- though the plant still needs some light in crete or hypertufa troughs with all sorts order to manufacture food for growth so you won’t find it in dark, shaded condi- Gnats in Your Face tions. If moss is growing under a tree canopy, careful and professional thin- Gnats have been bothersome recently. ning of the branches of trees and shrubs Numerous tiny flies hovering in one’s will bring in more direct light which it face can result in reduced productivity turn will thin out the moss. However, and distraction can result in physical you can’t easily move buildings if they injury. Rove beetles are also numerous, are causing the shade. appearing similar to gnats (small flies) while flying. Moisture may be more difficult to change, though not impossible. Eye gnats (Family Chloropidae) live as larvae in decaying organic matter. The Aerating the soil can help with drainage, recent frequent rains have aided in the though it may require several years of decomposition of dead vegetation from fall aeration to really make a difference. the winter, producing the organic mush Adding organic matter may increase needed for their development. Mature drainage initially, but would need to be larvae pupate with adult flies emerging added every two or three years as it a few days later. Adult eye gnats are breaks down. black and about 2 mm (1/16 inch) long. They feed on secretions of the eyes and French drains can funnel water away noses of people and other mammals, re- from low-lying areas if aeration doesn’t sulting in their common name. They are work. In large areas, underground tiles also attracted to secretions of the geni- may work. tals of male dogs, resulting in various colorful colloquial names. Of course, watch your irrigation. If moss is unwanted, avoid watering those areas Buffalo gnats (Family Simuliidae) are when irrigating. Reposition sprinklers also known as black flies. Their larvae or choose a type that allows you to di- are filter feeders in streams and rivers, rect the water to certain areas and avoid using mouth fans to strain out tiny crea- others. There’s not much you can do to tures and organic debris in the water control rainfall. current. The larvae of most species only survive in clean water. Efforts to reduce Herbicides are limited because the plant soil runoff and pollution of streams have has no vascular system, which is why allowed these and other insects such as grass and broadleaf weed killers provide mayflies, stoneflies, and caddisflies to no or limited control. Instead, products become more numerous in Illinois. Adult containing iron in the form of ferrous buffalo gnats feed on the blood of mam- sulfate or ferrous ammonium sulfate mals, birds, reptiles, and amphibians, compounds seem to provide the best frequently being specific to particular control. There are some herbicidal animals. The buffalo gnat species flying soaps, usually potassium salts of fatty at this time do not appear to be biting acids, that also claim some control. people, but become nuisances flying Though with all products, if the site con- around one’s face. They are half again ditions aren’t modified, the moss usually larger than the eye gnats, being about 3 returns. (David Robson) mm long, and black. Typically in June, buffalo gnat species emerge that bite eggs laid. Refer to the articles on emer- humans and birds, being nuisances to us ald ash borer in Issue 3 of this newslet- but killing poultry and other birds ter for further information. (Phil Nixon) where they are numerous.

Rove beetles are slender with pointed Modified Growing Degree Days (Base abdomens and shortened wing covers 50°F, March 1 through May 21) (elytra). They vary in size and habits Histori- with various species being herbivores, Station Actual cal Aver- One- Two- predators, or scavengers. The currently Location Total age (11 Week Week year) Projection Projection numerous species are black with brown Freeport 356 358 434 523 St. Charles 338 342 410 492 elytra and are about 3 mm long. Many DeKalb 364 394 448 543 insects will taste what they land on to Monmouth 452 447 537 637 Peoria 471 481 558 660 determine whether it is edible. Tiny rove Champaign 502 488 596 704 beetles such as these commonly produce Springfield 578 546 682 797 Perry 564 518 656 761 noticeable pinch-like nips when they Brownstown 545 600 654 775 Belleville 754 630 866 989 land on your skin. Rend Lake 756 682 875 1005 Carbondale 719 645 832 957 Dixon 742 698 860 990 Insect repellents containing DEET are Springs effective although those with floral fra- grances may be attractive to rove bee- tles. Small rove beetle species commonly Insect development is temperature de- feed on pollen. Hats with netting that pendent. We can use degree days to help protect the head from bothersome in- predict insect emergence and activity. sects are also available. (Phil Nixon) Home, Yard, and Garden readers can use the links below with the degree day ac- cumulations above to determine what Emerald Ash Borer insect pests could be active in their area.

Emerald ash borer adult emergence was GDD of Landscape Pests reported in southern Illinois in early GDD of Conifer Pests May. They are being found at this time, mid-May, in central Illinois. They should Degree day accumulations calculated start emerging in northern Illinois using the Illinois IPM Degree-Day Calcu- around the end of May into early June. A lator (a project by the Department of major means of control relies on killing Crop Sciences at the University of Illi- the newly emerged adults as they feed nois and the Illinois Water Survey). on ash leaves, reducing the number of (Kelly Estes)