Midwest Factsheets

July 2010

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Comparing Cool-season Lawn Fertilizer and Pesticide Programs: Aesthetic and Economic Trade-offs

Victoria Caceres, Doug S. Richmond and Cale A. Bigelow – Purdue Univ. Entomology and Agronomy Departments

There is increasing public interest in alternatives to traditional cool-season lawn fertilizer and pesticide application programs. Historically these programs have been based on calendar driven fertilization and the attitude toward pesticide applications has been a prophylactic approach for controlling broadleaf and annual grassy weeds as well as insects like white grubs. As consumer attitudes toward the perception of a “perfect lawn” begin to change, alternative management methods that involve more judicious pesticide applications and engaging in Integrated Pest Management (IPM) and scouting approaches these practices may become more publicly accepted. Furthermore, there is a very strong interest in “organic” products and approaches to lawn care. Currently, the information regarding longer-term performance of organic products in the field is very limited.
To examine the effects of these potential lawn management alternatives, an interdisciplinary field study was conducted between the Entomology and Agronomy Departments to evaluate four disparate lawn management programs which were: a traditional calendar driven consumer program (CP), a natural organic program (NOP), an integrated pest management/scouting program (IPM) and all were compared to a no input program (NIP). All programs with the exception of the NIP received approximately 3 # N/1000 ft2 annually with the NOP relying on manure-based fertilizers, corn gluten and entomopathogenic nematodes for annual grassy weed and insect control, respectively. The IPM program used traditional products but pesticides were only applied when warranted or thresholds were met. The mixed cool-season turf stand was located in full sun, maintained at 3 inches and irrigated only to prevent severe stress and facilitate product applications. The plots were regularly assessed for appearance, greenness, and periodic growth measurements. Individual program maintenance costs were calculated based on product cost and estimated labor costs for product applications/scouting.

Study results: While there were seasonal differences for appearance, all programs except the NIP program provided a satisfactory lawn appearance and green color that would be suitable to most homeowners. While the NOP was sufficiently green there were significantly more broadleaf weeds in this program, which detracted from overall appearance. This result emphasizes the need to develop effective natural organic products for broadleaf weed management. Additionally, the economic benefits of scouting were calculated and showed that an IPM program is economically feasible (Table 1). Employing an IPM program illustrates the potential reduction in unnecessary pesticide applications and reduced input costs. It is important to note that the mowing costs were kept constant for all treatments.
It is important to note that these results are observations over only two growing seasons and the long-term implications of this study should be carefully considered. For example, it is possible that some weed or insect pests could become problematic, canopy greenness/turf density could decline in time and the overall appearance may be objectionable to some consumers. Nonetheless, this study provides the framework for future studies and may begin to allow lawncare professionals an opportunity to consider the possibility of providing an IPM/scouting service to clients that desire this management approach. It should, however, be noted that these consumers should also be willing to accept a less than perfect lawn (brown is the new green!!!) at certain times through the growing season.

A more detailed description of the results of this study it can be found in: HortTechnology  20:418-426. Caceres et al., 2010. Aesthetic and economic impacts associated with four different cool-season lawn fertility and pesticide programs.

 

Table 1. Comparative product and estimated labor costs for four disparate cool-season lawn management programs over two growing seasons. 

*Note this value is for two growing seasons and does not include mowing costs.

 

 

 

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