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Extension objectives: My extension program's overall goal is to improve the understanding and management of diseases of greenhouse and nursery crops.

  • To help growers better utilize new tools, including resistant cultivars, new reduced-risk fungicides, biological and biorational controls, and SAR (systemic acquired resistance) materials.
  • To identify new diseases confronting the ornamentals industry and develop control recommendations for these.
  • To develop new information that will lead to better management of diseases that commonly cause crop losses.
  • To communicate information promptly and effectively to growers, through participation in national and regional trade and extension meetings, extension newsletters, trade journals and publication in books and journals.

Impact on the Flower Industry:


Coleus Copper Glow with CVNV

Our studies on coleus downy mildew have identified a new Peronospora species, recently reported as a basil pathogen, as the cause of the disease (in collaboration with G. Holcomb, Louisiana State University, B. Eshenaur, Cornell IPM, and B. Lassaad, Univ. of Lullier, Switzerland). We have established that the pathogen can also affect agastache and perilla as well as basil. As a result of our control studies, specialist propagators and growers have been guided in identification and management strategies for this highly contagious new disease. We have also collaborated in the identification of a new virus on coleus, Coleus Veinal Necrosis Virus (CYNV).

PM on Petunia

Powdery mildew on petunia

In collaboration with Mary Hausbeck (MSU), research has been extended to growers on the environmental cues and management options for the powdery mildew disease of poinsettias. As a result, crop losses have sharply declined since a peak in 1992, and florists now rarely observe this disease. Most recently we have shared with growers trial results on new biological controls and reduced-risk chemicals that are effective for managing this disease. Knowledge of new management options for other powdery mildew and downy mildew diseases affecting snapdragon, miniature rose, gerbera, verbena and pansy has been extended as well. Comparisons of verbena cultivars for their susceptibility to powdery mildew have been published and extended at national and regional trade conferences and extension meetings. We have recently described a powdery mildew new to North America, causing crop losses in vegetatively-propagated petunia (in collaboration with L. Kiss, Plant Protection Institute of the Hungarian Academy of Sciences).


Fusarium isolate plate from mum stem.

Root and vascular wilt disease management guidelines for growers have been improved through studies on management of Fusarium oxysporum pathovars (on cyclamen and chrysanthemum) and Thielaviopsis basicola (on calibrachoa), as well as Pythium and Phytophthora species. Ongoing work at Cornell in collaboration with Gary Moorman (Penn State University) and Steve Jeffers (Clemson University) has improved knowledge of what oomycete pathogen species are present in greenhouses today, how they may be identified using new DNA technologies, how they interact with fungus gnat vectors, and how they may be better managed. We are learning how to track Pythium strains within the greenhouse. Many reduced-risk and biocontrol options have been identified. Floral and nursery product appearance and landscape performance for the consumer are improved through skillful root health management during crop production.

Margery is currently working with other ornamental pathologists across thephlox country on a book on the recognition and management of diseases of herbaceous perennials for APS PRESS See this website for the Compendium of Flowering Potted Plant Diseases, published in 1995, which covers diseases affecting many important floral crops.

Extension Publications

2008 Cornell Guide for the Integrated Management of Greenhouse Floral Crops

Margery doing extension

Margery Daughtrey providing extension information at a greenhouse.

downy mildew on coleus

Downy mildew sporulating on undersides of coleus leaves.