2017 ASHS Annual Conference

Growers and landscapers managing weeds in ornamental plants face unique challenges. In agronomic cropping systems, production of a single crop lends itself to effective weed control practices. Weeds can be managed through tillage and use of multiple labeled herbicides. Weeds are also not an aesthetic concern, but are managed only to prevent reductions in yield. In contrast, ornamentals are marketed and sold based upon aesthetic value, thus weed threshold levels are virtually zero. For most growers, weed control is their costliest production input. As limited postemergence herbicide options are available, growers must rely on preemergence herbicides and hand weeding. Hand weeding is extremely expensive with costs ranging from $1,300 to $10,000 per ha. Landscapers face similar challenges in that it is too expensive to handweed and mixed plantings are not conducive to herbicide applications.

The objective of my program is to solve current and future industry challenges through a three-tiered approach focusing on research, extension and teaching. My program focuses on developing proactive and reactive real-world solutions for growers and landscape professionals through research, disseminating findings to the industry through extension, and creating impactful educational programs to train the next generation of scientists and industry professionals. The objectives of each area are codependent, creating a seamless transition between each tier. By interacting with industry professionals at extension programs, current industry needs are communicated firsthand to researchers. As science-based solutions are developed, findings are disseminated back to the industry through presentations, at events, and through traditional and electronic media. This research is then applied to the classroom, bringing the most current solutions and methodology to students, industry, and extension clientele.

In nursery weed management, research emphasis is placed on determining how production variables, such as fertilizer rate and placement (topdress, incorporate, etc.), or irrigation regime, affect herbicide degradation and weed prevalence. This is accomplished by monitoring microbial respiration of substrates subjected to different fertilizer rates and placements and monitoring weed growth variables. Similar studies are carried out using different irrigation levels applied via different cycles. This research is not only allowing us to recommend different herbicides based upon fertilization practices and irrigation schedules, but also helps growers schedule applications based upon rainfall. We are also investigating the impact of different substrate variables on weed growth and herbicide performance, particularly focusing on herbicide leaching, efficacy, weed germination, and growth in different horticultural substrates. Collectively, these objectives will be used to develop more comprehensive weed management programs for growers based upon all production inputs.

Focus is also placed on landscape weed control by examining how different mulches interact with herbicides. To meet the needs of landscape professionals, laboratory tests are being conducted to determine how herbicides are binding to various mulch types and if efficacy or off-site movement is influenced. A one-year study, conducted by a graduate student, is being used to determine the annual cost associated with different mulch choices based upon how herbicide use influenced weed control and mulch degradation. A graduate student is also conducting research on how mulch types affect weed germination by quantifying light levels and monitoring weed germination in different mulch types used in landscapes. Lastly, research efforts are also devoted to invasive plants with emphasis on managing invasive plants in and around native or ornamental species. Collectively, this weed management research has provided graduate and undergraduate research and extension opportunities for seven students in two years.

 Extension activities focus on disseminating research results to the industry to increase knowledge, change behaviors, and improve situations and are accomplished through traditional presentations, field days, workshops, publications and online training. The most significant way we have disseminated our findings is through the development of three unique courses: Foundations of Lawn and Ornamental Pest Management, Masters of Lawn and Ornamental Pest Management and Weed Management Online. The University of Florida’s Pest Management University (PMU) was created as a collaboration between university and industry to deliver the latest research from various fields in a 2.5-day workshop for industry professionals. Both Foundations of Lawn and Ornamental Pest Management and Masters of Lawn and Ornamental Pest Management have been integrated into PMU, where professionals have saved over $336,000 since 2015 implementing more effective pest management practices. Stretching beyond Florida, Weed Management Online is an interactive online course, offered in both in English and Spanish, devoted to all aspects of weed control in ornamental plant production. Students from North America, Australia, Africa and Europe have taken this course with 90 percent reporting significant knowledge increase and changes in production practices following the course.

Another major component of extension programming is on-farm research. Not only do these trials generate publishable research, but also are used to model proper weed control practices on growers’ own farms. Since 2015, 10 on-farm research trials have been initiated at Florida nurseries. In one particularly impactful experiment, results showed a container grower they could decrease labor costs by over 70 percent by weeding every two weeks as opposed to the industry standard eight weeks. In a separate on-farm demonstration conducted in collaboration with county agents, a large container nursery modified soil recycling practices and herbicide application procedures resulting in a weekly savings of over $6,000 during the height of production season. Currently we have two on-farm trials in place to determine the benefit of new mulching technologies on long-term crops.

In addition to providing solutions to growers and landscapers across Florida, my program has contributed to the literature surrounding ornamental weed management, weed science, and extension programming. Since 2015, we have generated 16 peer-reviewed journal articles, 3 co-authored book chapters , 27 conference proceedings and abstracts, 24 extension publications, 3 extension course curricula delivered both in a traditional setting and online, and hosted over 100 extension based presentations, field days and workshops across the country reaching over 3,000 green industry professionals. While weed management in ornamentals is definitely a “hard to row to hoe,” this field is full of tremendous opportunities to contribute to the horticulture industry as a whole. We will get there, one weed at a time.