Weed of the month for September 2014 is Broadleaf Plantain

Broadleaf Plantain  

Biology: Broadleaf plantain (Plantago major) is a perennial, broadleaf weed that can be found in nutrient-poor soils; however, they prefer nutrient rich-soils that are moist and often high in calcium. Broadleaf plantain is a common weed in turfgrass, nurseries, and landscapes as it can tolerate very low mowing heights. It germinates from seed in late spring through mid-to-late summer and occasionally in the fall depending on temperature and moisture. It has a low growing rosette habit and tolerates close mowing. It's ability to surve a range of environments make broadleaf plantain a common turfgrass weed in North America.

Identification: Broadleaf plantain is anchored primarily by fibrous roots. Some describe the root system as having a central, short taproot with branched-out fibrous roots but my experience is that large, fibrous roots are common and that taproots (especially large taproots like a dandelion) are very uncommon. Broadleaf plantain grows with a rosette habit with leaves that can grow flat along the turfgrass canopy or more erect and upright depending on mowing practices. The plant produces leaves that form on long, broad leaf-stems (petioles) that may grow up to six inches long and four inches wide when left unmown or untreated. Young leaves are oval to egg-shaped, generally have 3-5 prominent veins, and are light green in color. As the plant matures, the leaves start to appear darker green, can be smooth or slightly hairy, and abruptly narrowing to the petiole (leaf stalk). Very prominent leaf veins run parallel to the margin and appear to originate from the attachment point at the petiole. Leaf margins are smooth (entire) and appear more crinkled and wavy as the plant matures. Though the leaves can appear waxy and dark- to bluish-green, the petioles often have a reddish color towards their base, or the origin point of the rosette. Broadleaf plantain can produce flowers from June through September on long, leafless flower-stalks that arise from the center of the rosette. Small, whitish petals emerge from the flower-stalk where seeds are produced in an oval-shaped capsule which can contain up to 30 viable seeds. It may often be confused with blackseed plantain (Plantago rugelii) which is similar in appearance. Additionally, it is thought that many plants characterized as broadleaf plantain may in fact be natural crosses between Plantago major and Plantago rugelii.  

Broadleaf plantain appearance in early spring. it will regrow all its leaves each spring. The purple coloring here is in response to cool, spring temperatures.

Cultural control: None known specifically for broadleaf plantain. Since its primary method of dispersal is through seed, control or removal of the plant prior to seed production could reduce the spread of this weed. However, mowing practices alone to remove the seed stalks will not provide adequate management since the plant can produce viable seed at low mowing heights (produces viable seed at about 2 inches and taller heights of cut). Proper turf management such as higher mowing heights, irrigation, and fertilization will help to produce a dense, aggressive turf which is the greatest defense against invading/germinating weeds. Broadleaf plantain thrives in compacted soils, moist or dry soils, and shady conditions. Some research suggests as well that this plant prefers high calcium soils, but high calcium soils are a common phenomenon in North American because the soil parent material is limestone. Plants can be removed by hand-weeding if there are only a few on the property.

Biological control: None known specifically for broadleaf plantain. Many new organic products contain the active ingredient iron HEDTA (FeHEDTA). Multiple applications of this product are required for control. FeHEDTA containing products injure turf less (can actually make turf darker green), but their efficacy for weed control is yet to be well documented.

Chemical control: Broadleaf plantain can be chemically controlled with several products such as repeat applications of two- or three-way mixtures of 2,4-D, dicamba, MCPP, or MCPA which are available in multiple formulations at local retailers. 2,4-D is the active ingredient that does most of the work in these mixtures. Herbicides that contain triclopyr (Turflon Ester) or triclopyr in combination with other herbicides, such as 2,4-D, can also provide good broadleaf plantain control in cool-season grasses.

For more information on weed control, search this blog and check out our Turfgrass Weed Control for Professionals Publication.

For archives of past weed of the month postings, visit our Weed of the Month Archive.

Aaron Patton, Turfgrass Extension Specialist
Leslie Beck, Postdoctoral Research Associate
Read More

Armyworms Invade Indiana

There appears to be a wide-spread outbreak of armyworms [Pseudaletia (=Mythimna) unipuncta (Haworth)] infesting residential turf across southern Indiana. These insects typically have 2 generations per year in this part of the country and we are in the midst of the 2nd generation of larvae. Adult armyworm moths lay their eggs in large masses and when the eggs hatch, the resulting caterpillars begin to feed and move across the infested area. When the larvae are small, this feeding causes little damage and may go unnoticed. However, As development proceeds, the larvae increase in size, consuming larger amounts of turf.
Armyworm taken from turfgrass in southern Indiana. Photo courtesy of B. Voges.

Where heavy infestations occur, a typical home lawn may seem to disappear almost overnight!! Feeding damage often appears to radiate out from a central point where the main infestation likely started. Although the damage can be alarming, armyworms are easily controlled with insecticides and the damage they cause, although unsightly, will not permanently damage the turf unless it is already stressed from drought.

A home lawn in southern Indiana showing typical armyworm damage. Photo courtesy of B. Voges.

Fortunately, most of Indiana has been experiencing adequate rainfall for the last few weeks, so turf should be resilient to this damage. Still, expect damage to get worse before it gets better. Good cultural practices including adequate fertility and irrigation will help the turf recover more quickly. The caterpillars we are seeing now will pupate by the end of September and attempt to remain in the soil over winter. Unless we experience an exceptionally mild winter, most pupae will not overwinter successfully.

For control information go to: http://extension.entm.purdue.edu/publications/E-61.pdf

Doug Richmond, Turf Entomologist
Read More