June 15, 2013
The latest research project, entitled Functional Biopesticides for the Lawn Care Industry, addressed the problem of white grubs and chinch bugs in lawn turf.

Landscape Ontario applied for and received funding from the Agricultural Adaptation Council (AAC). Laura Sider served as the program coordinator.

“There is a real need in the lawn care industry for pest management tools that are sustainable as well as being effective,” says a researcher on the project, Dr. Michael Brownbridge from Vineland Research and Innovation Centre. European chafer and hairy chinch bug were the two main turf pests examined.

The research team looked at different methods to determine whether biopesticides would be effective in Ontario’s climate and conditions. There was also evaluation on the influence that time of application has on effectiveness.

“With bio-based products, you have to use them under conditions where they’ll be most effective. For example, if the outside temperature is too high, it kills them and if it’s too low, it makes them inactive,” explained Brownridge.

“With the chafer, the older the larvae, the less susceptible they will be to the control product. So timing is absolutely critical,” said Brownridge.

Tests found that the most effective nematodes against European chafer were Heterorhabditis bacteriophora and Steinernema glaseri, which are registered under a variety of trade names. Even so, the best control using optimal timing and targeting the most susceptible stage of the grub resulted in a kill of only about half of the population. Brownbridge says this shows the need for additional work to determine treatment thresholds and highlights the importance of taking an integrated management approach to maintaining a healthy lawn.

Researchers also found that treatments applied in the spring and fall provided different levels of grub control. Those applied in the spring, when soil temperatures were less than ideal for the nematodes and the larvae were too old, were largely ineffective.

The fall treatments, which targeted younger larvae and soil temperatures were higher, provided about 50 per cent control. “Interestingly,” adds Brownbridge, “when experiments included a chemical treatment as a comparison, not once did the chemical controls show better results than the biological ones.”

In 2012, nematode (H. bacteriophora and S. glaseri) sprays targeting young European chafer grubs in infested turf (late August) reduced populations by 50 per cent. Spray adjuvants used with the nematodes were generally compatible (Slither 0.02 per cent, Yucca 0.8 per cent), although survival was poor in Termitafoam. “Use of Termitafoam is therefore not recommended together with nematodes,” reads the report.

Rhizomatous tall fescue (RTF) and regenerating perennial ryegrass (RPR) plots were established at the Guelph Turfgrass Institute; both out-performed the standard home lawn mix (HLM) in terms of improved survival through the drought of 2012, faster establishment and reduced weed ingress. Bird feeding damage was also observed exclusively in the HLM plots, which were right alongside RPR and RTF plots; soil core samples showed that more grubs were present in the HLM plots than the RPR plots.

In greenhouse trials, chafer grubs showed a preference for grasses in the HLM, and larval growth (as measured by weight gain) was lower in both RTF and RPR grass pots. These data indicate that the fescue and rye grasses could play an important role in mitigating white grubs in lawn turf.

Several biopesticides were tested against chinch bugs, but none provided the level of control seen in previous years. “This may have been a result of the extreme weather conditions (drought, heat) which affected chinch bug behaviour, causing the insects to seek refuge in the soil to escape effects of the heat. As a consequence, they would have been protected from biopesticide sprays; all of the products tested rely on direct contact to be effective,” says the report.

“Results from the trials show that microbial biocontrol agents can successfully impact chafer grub populations, but use of these strategies alone is likely to be insufficient to provide the levels of control required to eliminate feeding damage. “It will be imperative for the industry to incorporate use of these control tools with cultural practices that promote growth of a healthy lawn, together with the introduction of new grass varieties that can complement pest management efforts which contribute to a more sustainable lawn,” says the report.

Results have provided information on chafer control tools that can be used by the lawn care industry, in terms of product efficacy and application considerations. “The products are available from commercial producers and can be purchased by turf professionals. From this perspective, the project has achieved its goal. However, additional tools are still needed for chinch bug management, so additional work in this area seems warranted. In addition, integration of complementary tactics — how to achieve the best results with the combined use of cultural, i.e. grass selections, and biological pest management approaches — would be worthy of further investigation.

A simplified report may be found at http://bit.ly/turfresearch.