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

Contents

• Leading Crop Protection: A systematic approach to pest management
• Poinsettia Scab
• Take Care of Your PPE
• News from the Lab
• Rocky Mountain Greenhouse Short Course

Leading Crop Protection: A systematic approach to pest management

How do you make decisions regarding pest control in the greenhouse? Do you make chemical applications at regularly scheduled intervals? Is pest control utilized only when insect populations are high enough to be noticeable in the crop? There may be a better solution to your pest management needs, a strategy that is based on actual insect population numbers.

Leading crop protection is one facet of an Integrated Pest Management (IPM) strategy that uses real data to prevent insects from becoming a problem within your greenhouse, rather than reacting to situations after they occur. This type of proactive approach can help prevent large outbreaks of pests in the greenhouse, and may reduce the number of spray applications. Fewer chemical applications means decreased operation costs for the greenhouse manager.

The basic strategy is to carefully map out your greenhouse operation, indicating greenhouse ranges, aisles and benches. It is a good idea to map these out in a graphical manner, indicating the house and bench numbers. By making a spreadsheet, you can keep track of the bench location by week, documenting pest population fluctuations over time. It is especially helpful to compare the pest populations with the control measures employed to evaluate the effectiveness of different products.

Two types of monitoring are necessary: plant scouting and card counting. Plant scouting is typically conducted every week, and involves examining plants for the presence of harmful insects. This is not a cursory overview of the greenhouse, but a systematic inspection of specific plants. It is helpful to use a magnifying loop for this purpose. With certain pests, such as whiteflies, it is important to note all life stages, including adults, instars and eggs. A few adults might not be of great concern. However, presence of many eggs or larvae indicates that in a short time there will be a large-scale outbreak in the greenhouse. This means that control measures can be targeted to specific life stages of pests. Targeted control strategies can prevent pest outbreaks that are difficult to manage, at best. In a cut flower operation, it is best to inspect the plant in three sections: top, middle and bottom. When examining the crop, check each part of the plant, and record the number of pests. In a bedding plant system, simply examining each plant for insects should be sufficient, since they are not very tall.

Card counting involves the use of yellow sticky cards to trap insects. This will work for certain flying pests, like whiteflies and thrips. This type of pest monitoring is also conducted once weekly. Basically cards are hung directly over the crop, in specific locations within the greenhouse. Every week, the cards are examined and the number of pests is recorded. This is especially useful in the spring, to know when thrips begin their migration into your greenhouse.

Here is a sample data sheet for plant scouting, the recorded information appears in red:

Record keeping can lead to pest management strategies based on real data. Ideally, this will enable you to notice pest presence early, in time to prevent problems from occurring, rather than reacting to them once they become obvious. For this reason, we consider this facet of IPM "leading crop protection" because in the best case scenario, the grower stays one step ahead of the pests. This is a much preferable situation. As any grower knows, when insects get out of control, they are extremely difficult to manage. This is a very stressful situation to experience. On the other hand, preventing large scale pest outbreaks before they occur by utilizing a systematic approach and real data helps to make a challenging task more tolerable.

No endorsement of products mentioned is intended nor is criticism implied of products not mentioned. As always, before using any pesticide, consult the label.

Chris Freeman
Area Specialist Commercial Greenhouse
Adams County

Poinsettia Scab

Poinsettia scab is likely to be present in greenhouses this year. Growers are advised to become familiar with the symptoms, to identify affected plants and remove them from the greenhouse to prevent spread of the pathogen. The disease is caused by a fungus, Sphaceloma poinsettiae, and has entered the United States via infected cuttings from Central America.

Initial symptoms include necrotic brown spots up to 4 mm in diameter surrounded by 1 to 2 mm chlorotic halos as seen in Figure 1. As the disease progresses, entire sections of leaf tissue begin to die (Figure 2). Eventually entire leaves can fall off. The disorder gets its name from the scab-like raised wounds found on the main stem and leaf petioles (Figures 3 & 4). The scabs are usually tan in color, and the surrounding stem tissue may become discolored. Another symptom is unusual internodal elongation, resembling the effects of gibberellic acid treatment. The stem elongation, shown in Figure 5, usually occurs above a scab lesion. Figure 6 shows the overall appearance of an affected plant.

Figure 1. Leaf Spots	Figure 2. Leaf dieback
Figure 3. Stem Scabs	Figure 4. Scab on petiole
Figure 5. Stem elongation	Figure 6. Plant effect

Splashing water, which carries fungus conidia from plant to plant, spreads this disease. Susceptible species of plants includes members of the Euphorbia family, such as Mexican fire plant (Euphorbia heterophylla L.), painted euphorbia (E. prunifolia Jacq.) and cassava (Manihot esculenta Crantz). Infected plants do not always show all of the symptoms.

Vigilance will help to minimize the loss from this disease. When affected plants are found, they should be placed inside plastic bags and removed from the greenhouse. Plants adjacent to infected specimens should be carefully scrutinized for early signs of the disease. Any measures that minimize water splashing, such as drip irrigation will help to minimize the spread of this pathogen. Fungicide treatment will help also. Systhane (myclobutanil), has been very effective in trials. This product is registered for control of powdery mildew on poinsettias. A real benefit of this product is that it has been used without phytotoxicity on poinsettias. Other treatment options include Zyban thiophanate-methyl plus mancozeb); Dithane T/O, Fore T/O, Pentathalon, & Protect T/O (all contain mancozeb alone); Cleary's 3336, Fungo Flo, SysTec 1998 (all contain thiophanate-methyl alone); or Spectro (contains thiophanate-methyl plus chlorothalonil).

No endorsement of products mentioned is intended nor is criticism implied of products not mentioned. As always, before using any pesticide, consult the label.

Chris Freeman
Area Specialist Commercial Greenhouse
Adams County

TAKE CARE OF YOUR PPE

In the health and safety profession, there are three types of control methods that can be used to mitigate hazards: engineering controls, administrative controls, and personal protective equipment or PPE. Notice how PPE is the last control method mentioned. There's a reason for that. PPE is considered the last line of defense. It's the equipment that employers purchase and employees wear because other types of solutions weren't available, were too expensive, or were impracticable. The biggest downside to personal protective equipment is this: if the PPE fails the worker is exposed.

This article will focus on chemical protective clothing - gloves, boots, aprons, and suits. These articles of PPE are worn to prevent contact of chemicals with skin. The skin is the largest organ in the human body. Chemicals can damage the skin directly or move through the skin to the bloodstream where they can damage other organs and tissues. About a third of reported occupational illnesses are skin disorders. Examples include contact dermatitis, photosensitivity, occupational acne, pigment abnormalities, cancers, and burns. Carbon tetrachloride, O-P pesticides, and toluene are examples of chemicals that can be absorbed through the skin into the bloodstream. Chemical labels and material safety data sheets (MSDSs) will provide information on the type of skin hazards posed by a chemical.

These are some of the questions that should be asked when selecting and using PPE:

• Does each worker's equipment fit properly?
• Is the glove/apron/boot/suit material resistant to the chemicals being used?
• Which is more practical? Disposable or reusable equipment?
• Does the task involve handling or maneuvering around sharp edges or protrusions that could damage PPE?
• Are employees who wear PPE trained on how to wear and take care of it?
• Are employees who wear PPE trained to recognize the symptoms of heat stress?
• If equipment is to be reused, does the employee inspect it for damage before each use?
• If equipment is to be reused, does the employee clean it according to manufacturer recommendations?
• If equipment is to be reused, is it stored is a cool, dry place away from chemicals?
• Do employers and employees allow extra time to perform tasks that require PPE, since it is usually more cumbersome to work while wearing it?
• Do employers and employees realize that if the PPE fails, the worker will be exposed to whatever hazard they were trying to protect themselves from and they may not know they are being exposed right away?

The following photo is an example of poor PPE maintenance. The equipment in the photo has not been cleaned and is not stored properly. This equipment is unsafe for the worker to wear. Simply touching the contaminated gear will expose the worker to the chemical that wasn't cleaned off of it following the last use. How does the worker know that there aren't chemicals inside the equipment?

	Photo provided by High Plains Intermountain Center for Agricultural Health and Safety

PPE can be damaged by heat, direct sunlight, or if stepped on or rolled over by people and equipment. When new, protective clothing comes with instructions on how to care for it and store it. Follow these instructions. Employers who expect employees to maintain their PPE should provide the employees with a place to wash and store the PPE.

Equipment should be inspected prior to each use. Look for the following: · Pinholes and larger holes;

• Areas of discoloration;
• Cracks; and
• Other changes in appearance.

Each of these can be a sign of damage to the protective material, and damaged protective gear won't protect the worker. Damaged gear should be thrown away!

Once a glove, or other piece of protective clothing, is exposed to a chemical it's useful life is decreased. No glove material is "impermeable". In fact, the rate of permeation through the protective material depends on the chemical, the type of contact (splash, vapor, etc.), and length of contact. The greater the surface area of the material exposed to the chemical, and/or the longer the contact time, the greater the chance that chemical will permeate the glove. Once that happens, the glove is no longer useful and has to be thrown out. In this situation, the worker would be exposed to the chemical that permeated the clothing.

Take care of your PPE so it can take care of you.

References:
Mansdorf, Z. "Chemical Protective Clothing" Short Course. 2000.
Plog, B. "Fundamentals of Industrial Hygiene, 4th Ed." 1996.

Tina Daniels
HICAHS Safety & Health Consultant and
Extension Farm Safety Specialist
CSUCE Agriculture Health and Safety

News from the Lab

We have a new face in the Postharvest Floriculture Laboratory. This month, let me introduce you to John Ray.

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

Hi, I'm John Ray. I've just been hired on at CSU as the Floriculture Research Associate. I'm originally from Richmond, VA, but I moved to Colorado in 1984. After graduating from CSU with a Bachelor's in Horticulture Science in 1989, I ran a small mail order nursery in Denver while waiting for my wife Gayle to graduate. Afterwards we both went on to get our Master's degrees at Purdue University. Gayle's was in Horticulture, mine in Agriculture Systems management.

Gayle wanted to continue her education so we moved to Cornell University in upstate NY where for nearly five years I worked as a Pomology research technician in the Fruit and Vegetable Science Department growing Apple, Peaches, Pear, Chestnut and Pawpaw. After Gayle's Ph.D. we moved to WSU in Pullman, WA for her post-doc where I worked as a technician for the USDA-ARSs' Wheat Genetics, Quality, Physiology and Disease Research Unit doing winter wheat cold hardiness research in their new greenhouse/growth chamber facility.

Gayle was fortunate enough to land a job working with the USDA-ARSs' National Seed Storage Lab here in Ft. Collins as their new clonal preservation physiologist, so back to the Choice City we came to find old and new friends. On January 4th, Emily Margaret was born so I'm also learning how to be a father. We've just bought a house so I guess we're "settled down" now.

I'm brushing up on some rusty molecular genetics skills trying to help Dr. Michelle Jones' group get some new and improved, super-dooper, long lasting flower varieties into growers' hands. I'm also working with Dr. Steve Newman so undoubtedly you'll be seeing me hanging on for dear life as he drives me around Colorado setting up various research trials in whatever growers ranges we can find.

I'm really excited about being back in this beautiful state and working with such a great group of people, and if you're ever up in the Horticulture Department on campus, stop in and look me up and I'll show you what we're doing.

John Ray
Research Associate
Horticulture and Landscape Architecture

Colorado State University Cooperative Extension and the Colorado Greenhouse Growers Association is pleased to announce the 2000 Annual Rocky Mountain Greenhouse Short Course.

October 18-19, 2000 at the
Arvada Center for Arts and Humanities
6901 Wadsworth Blvd., Arvada, Colorado

The topic for the program this year is Understanding Greenhouse Nutrition and Media Technology. We have four top speakers who will be providing the material. Contact Bob Briggs at the CGGA Office for more information or download the brochure by clicking on the link below.

Download the Brochure
requires Acrobat Reader

Plan to attend the CGGA 75th Anniversary Gala
Wednesday 18 October, 2000
Keynote speaker will be Paul Ecke, III
Paul Ecke Ranch

Contact the CGGA Office for details

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