A Newsletter for Professionals Growing Greenhouse Crops in the Rocky Mountain Region

Contents

• Welcome to the New Year
• Downy Mildews
• News from the Lab
• 1999 Poinsettia Evaluation

Welcome to the New Year

January 2000 as usual has proven to be one of the busiest times of the year. All of us in the Horticulture and Landscape Architecture Department have been involved in ProGreen, the Wyoming Groundskeeper and Growers Conference, or just getting ready for classes. In addition to all of this, our Department along with the rest of Colorado State have been involved in a curricula exercise, which has meant dropping credit hours for graduation from 128 hours to 120 hours, implementation of a new academic core, and the reduction of course offerings by our Department by about 20%. Needless to say, this has been a difficult exercise, but our Resident Instruction Committee has completed this task with the needs of our students and respective industries in mind.

The basic changes in the Floriculture concentration in the Horticulture major can be highlighted with a few comments. Students enrolling in the fall semester of 2000 in addition to their traditional horticulture training, will complete a foreign language requirement, Spanish, take more business courses, complete a required internship, and complete courses in a uniform core emphasising global and cultural awareness, health and wellness, historical perspectives, US public values, and institutions logical/critical thinking. We have done this in such a way that enhances our Practicum program and includes a capstone course that will allow students to participate in activities that provide hands-on experiences. Watch for more information in future newsletter editions.

Career Day 2000

Career Day 2000 is scheduled for February 23, 2000. This is an excellent opportunity for you to come to campus and recruit new employees or student interns. For more information, you can contact Dr. Jim Klett or our Department office. Also, you can download a registration by clicking the link below:

Download the Information Form
requires Acrobat Reader

Steven E. Newman, Ph.D.
Greenhouse Crops Extension Specialist
Horticulture and Landscape Architecture

Downy Mildews

Downy mildews are not a common problem in Colorado greenhouses, but appear sporadically each year during the cooler months, late fall through early spring. Plants commonly affected by this fungal disease are snapdragons, roses, and pansies, however the disease can also occur on anemone, ornamental pepper, lisianthus, African daisy, impatiens, monkey-flower, cineraria, primrose, herbaceous potentilla, and rannunculus, among others.

Symptoms vary, quite a bit, depending on the causative fungus (there are three common genera that attack flowering plants, Bremia, Peronospora, Plasmopara) and the type of plant. Downy mildews are host specific, for example the disease on roses is caused by Peronospora sparsa while the same disease on lisianthus is caused by Peronospora chlorae and on snapdragons it is caused by Peronospora antirrhini. None of these species will infect another plant type. On most plants symptoms are conspicuous, irregular or angular shaped patches that appear on upper leaf surfaces. The patches range in color from light green or yellow to wine red or purple. (Almost like a chimera or genetic abnormality). Beneath these symptoms (on the leaf undersides) a light brown or gray felt-like growth will appear. This growth is sporulation (the fungus itself) and is diagnostic for the disease.

Downy mildews develop under conditions of high humidity, prolonged leaf wetness, and cool weather. Generally, temperatures ranging from 59F to 70F are conducive to the development of these diseases. When outbreaks of disease occur, every effort should be made to remove symptomatic plants as well as weeds. The fungi will reside in infected plant debris, in the soil, and on weed hosts. Conditions that allow for prolonged leaf wetness should also be avoided, if possible. The following fungicides have shown some effectiveness against downy mildew: mancozeb, fosetyl Al, and metalaxyl. Make sure the appropriate plant is labeled prior to use.

Laura Pottoff
Extension Pathology Agent
Jefferson County

News from the Lab

Improving Postharvest Quality of Floriculture Crops

This article is a continuation from last month.

Postharvest quality of floriculture crops is a concern to every greenhouse grower, as well as the consumer. Our research objectives to improve postharvest quality include:

1. Determine the biochemical and physiological basis of flower senescence;
2. Use molecular biology to identify genes involved in the regulation of flower senescence and determine the role of the plant hormone ethylene in regulating these genes;
3. Utilize these senescence-related genes to create transgenic plants with longer-lived flowers and evaluate flower longevity and ethylene production in these plants; and
4. To investigate the feasibility of ethylene inhibitors for the commercial treatment of floriculture crops to increase flower longevity and quality and prevent petal abscission.

To achieve these goals, the Colorado Agriculture Experiment Station has established the research project, Improving Postharvest Quality of Floriculture Crops, to advance our understanding of these issues. Equipping the Postharvest Floriculture Laboratory is nearly complete and we now have some new faces who are actually doing much of the work. Last month, you met Dr. Felicity Johnson Potter. This month, let me introduce you to Sarah Ball.

Michelle L. Jones, Ph.D.
Assistant Professor of Floriculture
Horticulture and Landscape Architecture

I am from New Zealand and a graduate of Massey University's Horticulture Department and have recently completed my M.Sc in Horticultural Science at the University of Guelph in Ontario, Canada. I have specialized in postharvest physiology of fruit and vegetables and have worked with the Postharvest Science group at the Mt Albert Research Centre in Auckland, New Zealand and with the postharvest program at the Horticultural Research Institute of Ontario, Canada.

I am currently a research associate in the Department of Horticulture and Landscape Architecture at CSU, sharing my time between Dr. Michelle Jones (postharvest quality of floriculture crops) and Dr. Yaling Qian (turfgrass stress physiology).

One of the projects I am involved with in the Postharvest Floriculture Laboratory is investigating a gene involved in petal senescence. Senescence is a highly regulated process of programmed cell death or apoptosis. The gene we are interested in is called the dad gene, which stands for Defender against Apoptotic Death. The dad gene was originally identified in animals and has been shown to be essential for cell survival. Recently, similar genes belonging to the dad family have been found in plants and have been identified as repressing senescence where the gene is turned on.

The objectives of our project are to identify the dad gene from carnation and petunia, and to determine whether this gene plays an important role in suppressing flower senescence. We need to determine whether the dad gene is present in senescing or non-senescing petunia tissue, and whether stimuli such as ethylene or pollination turns the gene on or off. We hope that by genetic modification to increase the level of the dad gene in petals, we can effectively delay senescence without affecting other developmental processes. If this is the case, we will use the dad gene to create transgenic plants which have delayed flower senescence, resulting in long-flowering bedding plants and long-lived cut flowers without the need for chemical treatment. Since we will be delaying senescence by targeting senescence-related genes rather than inhibiting ethylene biosynthesis or action we will potentially be able to apply this technology to delay senescence in ethylene insensitive as well as ethylene sensitive plant species.

Sarah Ball
Research Associate
Horticulture and Landscape Architecture

The Colorado State University Annual Poinsettia Trial was a success. You can view the results at:

1999 Annual Poinsettia Evaluation

Steven E. Newman, Ph.D.
Greenhouse Crops Extension Specialist
Horticulture and Landscape Architecture