Purdue Turf Tips: July 2013

White Grub Season Approaching: Remember to Follow Label Directions

Last month, a commercial landscape manager in Oregon made an off label application of dinotefuran to flowering linden trees resulting in the death of more than 25,000 bumblebees and immediate action by the Oregon Department of Agriculture to implement a six month ban on all dinotefuran products labeled for landscape use http://www.oregon.gov/ODA/docs/pdf/news/130627dinotefuran.pdf

The labels on dinotefuran products and all other neonicotinoid products marketed for turf and landscape use (imidacloprid, thiamethoxam and clothianidin; see table 1 below) contain clear and concise statements warning of the potential environmental hazards associated with applications to flowering plants. One example of a potential environmental hazard is the potential negative effects of these insecticides on bee populations which have declined in recent years.

This unfortunate incident should serve to remind us all about the potential costs of ignoring label directions. One mistake can cost an entire industry the use of critically important tools and, as we’ve seen in the Oregon case, State agencies can and will ban these insecticides in order to protect human and environmental health.

As many folks start to think this time of year about making insecticide applications to protect their lawns from white grubs, it may be prudent to keep a few things in mind.

In any given year only about 20% of home lawns will be afflicted by damaging white grub populations in this part of the country.
The likelihood of a given lawn being afflicted with damaging white grub populations 2 years in a row is only about 50%
Some of our most common lawn weeds, such as white clover, provide excellent forage for bees and other beneficial insects, so proper weed control is a must if neonicotinoid insecticides will be used to control insect pests. In other words, if the lawn is weed free then an application of one of these insecticides should not pose a hazard to bees, but if the lawn has high populations of flowering clover these insecticides should not be applied.
Since neonicotinoids are systemic compounds that are readily taken up by plant roots, it may be advisable to maintain a reasonable buffer area between treated areas of the lawn and landscape beds where flowering plants that are likely to attract pollinators are less likely to take these products up through their roots.
When possible, it may be prudent to wait until after flowering to apply systemic insecticides to trees or other flowering plants to allow nearly a year between the application and the production of new flowers.

At the very least, use common sense and do your part by following the label.

Table 1. Trade names of turf insecticides containing a neonicotinoid as one of the active ingredients.

Common Name/Active Ingredient	Trade Name
dinotefuran	Zylam
clothianidin	Arena, Aloft
imidacloprid	Merit, Allectus and many post-patent products
thiamethoxam	Meridian

Doug Richmond, Turfgrass Entomologist

Cliff Sadof, Landscape Entomologist

Aaron Patton, Turfgrass Extension Specialist

Goosegrass

Biology: Goosegrass (Eleusine indica) is an late-germinating summer annual grass that is often found in compacted areas or areas disturbed in the summer. These areas include compacted areas next to sidewalks or cart paths, golf course tees, and areas were soil is disturbed during the summer. Germination typically starts about two to three weeks after crabgrass germinates in early May in most Midwestern States although goosegrass is less common in northern areas of the Midwest like Michigan, Minnesota and Wisconsin.

Identification: Goosegrass is a prostrate growing summer annual grass which forms a mat-like rosette. Its flattened leaf sheaths are typically a white to silver color, especially at the base of the leaf sheath. Because of this coloration and its similarity to crabgrass some call it silver crabgrass.

Seedlings develop several leaves (sometimes six or more) before tillering.

As the plants mature they tiller and become very tough and more prostrate in growth (especially in mown turf). Goosegrass produces seedheads from July to September in Indiana. The seedheads are similar in appearance to crabgrass but the seeds are slightly larger than crabgrass seeds and the spikes on the seedhead are often described as being “zipper-like” in appearance.

Furthermore, goosegrass can be distinguished from crabgrass by its leaf arrangement. Goosegrass leaves are folded in the bud (emerge from the sheath as folded) whereas crabgrass leaves are rolled in the bud (emerge from the leaf as rolled).

Cultural control: Reduce soil compaction through aerification and improve turf density.

Biological control: None known.

Chemical control: Goosegrass is best controlled with preemergence herbicides. Herbicides that contain oxadiazon (Goosegrass/Crabgrass Control, Ronstar, Oxadiazon) are the most consistent products for preemergence control of goosegrass. Other preemergence herbicides typically provide less goosegrass control than oxadiazon but can be effective where goosegrass is not too problematic.

Apply oxadiazon at the same preemergence application timing as a normal crabgrass application (the timing varies by location, but it is generally before April 15 in the Midwest). In areas with severe goosegrass pressure, consider a split application approach. Make the initial application at the normal crabgrass preemergence timing at half the rate, and then apply the second (sequential or split) application 60 days after the first.

For postemergence goosegrass control in cool-season turf, use fenoxaprop (Acclaim Extra), mesotrione (Tenacity), fluazifop (Fusilade II), topramezone (Pylex), or MSMA (golf courses and sod farms only). More than one application of these herbicides may be required for postemergence control of tiller goosegrass. Sulfentrazone (Dismiss) is also effective on pre-tillered goosegrass. These herbicides are labeled for specific turfgrass species or are labeled for use in specific areas. Consult the labels and identify your turfgrass species before application.

Postemergence controls in bermudagrass includes foramsulfuron (Revolver) and Tribute TOTAL (thiencarbazone + foramsulfuron + halosulfuron). You can use Fusilade II and Acclaim Extra on zoysiagrass. Fusilade II and Acclaim Extra work best when tank-mixed with 1 qt/A of triclopyr (Turflon Ester Ultra or Triclopyr 4). When controlling goosegrass avoid applications to drought- or heat-stressed turf.

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

Aaron Patton, Turfgrass Extension Specialist

2013 Turf and Landscape Field Day a Success

On Tuesday, July 9th, 2013 the Purdue Turf Program and the Midwest Regional Turf Foundation hosted the Turf and Landscape Field Day. The Turf and Landscape Field Day is Indiana’s largest green industry field day. It was a much cooler day than last year and we were thankful that the rain stayed away and the breeze made it nice and comfortable for our attendees.

A first at this year’s field day was the addition of landscape research tours, where specialists from four different departments in the College of Agriculture shared their findings and recommendations to Green Industry professionals. It was a great opportunity for those attending to receive education, research updates, product updates from the exhibitors, and also a great opportunity to network with others in the Green Industry.

The field day featured 38 exhibitors representing companies from around the region ranging the gamut from equipment, seed, fertilizers, pesticides, landscape plants, hardscape and more. The 474 attendees where mostly from Indiana and all its surrounding states but many national representatives were also there from various companies to learn more about Purdue’s latest green industry research. Attendees came from a variety of backgrounds including business owners, managers and staff of wholesale and retail nurseries, landscape management firms, greenhouse growers, golf course superintendents and staff, lawn care companies, grounds maintenance departments, landscape design and installation firms, garden centers, consulting firms, educational institutions, suppliers and more!

This year’s field day provided three morning research tours and four afternoon tours including a popular field trip to Purdue Horticulture Gardens. Sixteen different speakers were at the field day including Purdue faculty/staff from Agronomy, Botany and Plant Pathology, Entomology, Horticulture and Landscape Architecture, and Forestry and Natural Resources. The field day was a success again this year and continues to be a leading provider of information and education among the Midwest turf professionals and the Green Industry.

Mark your calendars for next year’s Turf and Landscape Field Day, July 15, 2014.