Cost of IPM scouting: A case study wtih Poinsettia

Alan H. Michael, Roland Freund, Judy Smith, Robert D. Berghage

In 1995 a greenhouse crop management association (CMA) was started in the Capital region of Pensylvania. Since then this association has been very successful. Total grower membership tripled, from five in 1995 to 15 in 1998. CMA members have been able to document reductions in pest problems including: impatiens necrotic spot virus, western flower thrips, whitefly and many other pests and diseases. Plant losses have decreased while plant quality has improved. Pesticide usage has also decreased resulting in reduced worker exposure.

When greenhouse CMA members were asked to place a value on crop consulting services (primarily scouting) all found it difficult to quantify. Even though members agreed that the service was worthwhile and the actual value was three to four times greater than the cost of scouting, none were able to provide records to substantiate these conclusions. A systematic cost accounting was needed to accurately evaluate the cost of IPM scouting relative to all other crop costs. To address this need, the Pennsylvania Department of Agriculture's IPM Program, Penn State Cooperative Extension, and the Greenhouse Crop Management association decided to cooperate in an analysis of IPM costs for the 1997 poinsettia crop. Case studies were utilized to complete this project which started in the summer of 1997 and continued through December 1997. Funding was provided by the Pennsylvania Department of Agriculture's IPM Program. Production data was provided by cooperating commercial greenhouses. Reports were collected by the Lebanon-Lancaster Crop Management Association's crop consultant, then analyzed by Penn State Extension.

The focus of this study was limited to the finishing phase of poinsettia production from planting of a rooted cutting to shipping the final product. Even with this clear focus it was difficult to reliably define the starting and end points of the analysis. Some growers may consider cleaning out the residue of a former crop as part of the preparation for poinsettias, while others may start with an empty and clean greenhouse. Production controls and management items like automatic misters, irrigation systems, driptubes and shade require setup time. There may be differences in the packaging requirements for plants which are trucked away to wholesale distributors versus those which are sold retail from the facility. The important thing is that packaging and carryout are still activities which must be included in the production costs. Every attempt was made to ensure data were similarly reported from each grower. Data were initially collected from four commercial greenhouses as part of a weekly IPM crop scouting program from July through December 1997. Two of the four growers were unable to provide all the data required and dropped out of the project. Data for this study were therefore summarized from two greenhouses: case #1 was a large grower (over 200,000 ft2) with a high capital investment including central heating; case 2 was a smaller grower with 10,000 ft2, a lower capital investment, and heating provided by unit heaters located in each house. Crop records were maintained by greenhouse workers as various production practices were completed. Data sheets were collected and reviewed weekly by the CMA crop consultant. Her familiarity with the greenhouse operation and its employees allowed her to interact and coach workers charged with keeping data ensuring consistency, and helping to reduce errors. We found workers willing to collect and record data if it was easily integrated into their normal work schedule and did not require calculations or substantial writing. Recording forms for a record keeping system that relies on workers must be simple and straight forward. Growers and managers who were involved in this study from beginning to end were those same growers who already were keeping some records. Growers who dropped out or provided incomplete records had little history of detailed record keeping and managers placed less value on having their workers spend time keeping detailed records or redoing incomplete records. It is worth noting that if the greenhouse crop consultant had not diligently coached and reviewed the workers record keeping procedures, especially during the first few weeks, it would not have been possible to provide the required accuracy and consistency. The crop consultant was able to provide exact plant counts at the start of the crop and noted losses each week, especially plants that were discarded due to disease or poor growth, as well as unsold plants at the end.

Input costs.
Data collected included costs and quantity of all inputs (variable costs) such as usage of pots, media, fertilizer, cuttings, pesticides, and packout materials. Scouting cost was also considered an input, as the scouting is contracted by individual greenhouses. Energy records utilized monthy gas and electrical. It was not possible to isolate the energy cost for only 6-inch poinsettias, since other sized poinsettias were also being grown, so costs for the growing period were allocated.

Labor costs.
The number of person-hours spent on each task, such as planting, pesticide application, maintenance, spacing, watering, and packout, was recorded No effort was made in this survey to distinguish between permanent and casual workers nor to assign different wage rates based on pay scale. An arbitrary rate of $10 per hour was used to cover wages, fringe benefits, taxes, workman's compensation etc. Supervisory or managerial labor working in the production process was counted as regular labor hours. An allowance for managerial overhead was assigned as a fixed cost in the overhead calculation.

Overhead costs.
These costs included both capital and fixed costs. Market value was used for assigning land use costs. Office and storage buildings; heating, venting, irrigation, and other greenhouse equipment were assigned an estimated replacement value, depreciated, and amortized at 8.5% interest. Grower interviews were used to estimate useful life of buildings and equipment, opportunity-cost, interest rates, greenhouse, and general maintenance costs; as well as repair, supervision and management costs. Only summary data are reported and discussed in order to protect the confidentiality of the growers.

Results:
The larger, higher investment greenhouse had both greater labor efficiencies and lower variable inputs costs, but higher overhead. In this study the larger greenhouse had a break-even cost of $2.79; whereas, the smaller, lower capital investment greenhouse had a break-even cost of $3.07 for each six inch pot poinsettia. This occurred even though the smaller greenhouse had a plant loss of 3.7% verses 8% for the high investment greenhouse. As would be expected, the larger operation was able to purchase many inputs at a lower cost than the smaller operation. The cost of a 6" pot was 3.7¢ for the large greenhouse compared with 6.2¢ for the smaller facility. There was a similar cost differental for growing medium, 9¢ vs. 16¢, respectively. In contrast packaging material and rooted cutting cost were similar for both operations.

The rooted cutting cost was similar, however it is important to note that the cutting cost used was the price of purchased cuttings. The smaller greenhouse purchased all their rooted cuttings, but the larger greenhouse purchased only a portion of their total cuttings, the majority they grew and rooted themselves. No attempt was made to analyze cutting production costs but the larger producer indicated that their self-produced cuttings may have been 25% cheaper than those they purchased.

Heating was more efficient in the high investment greenhouse. The smaller greenhouse was heated with bottled propane with individual heaters in each greenhouse and had a total energy cost of 36¢ per pot. The larger grower had central boilers burning natural gas resulting in a total energy cost of 27¢ per plant. Energy costs were allocated based on the finish spacing of the crop. No attempt was made to address cost allocation to any empty portion of the greenhouse. This may be misleading if for example poinsettias occupied only half of the space and the rest was empty.

The larger operation achieved a much higher labor efficiency for many tasks such as planting, watering, and shipping. Spacing was a notable exception. The larger greenhouse devoted 41% of the total hours to the moving and spacing of plants.

IPM and Scouting Costs were similar for both greenhouse operations. Compared to other costs, crop scouting was almost negligible. In this study crop consulting costs (scouting) were equal to 0.3% (less than 1 cent per plant) of total costs required to finish growing a six inch poinsettia (average $2.93) Analysis of all costs indicated that variable inputs accounted for about 55%, labor 18%, and overhead 27% of total costs.

The results from these two case studies provide an interesting glimpse of the cost of producing six inch poinsettias in south central Pennsylvania. The authors realize and emphasize that the information presented are based on only two case studies. It is suggested that these data be used for comparison only. It is necessary that individual growers collect their own records to ensure accuracy for proper decision making.

• Do not feed deer. This only develops a feeding pattern that is difficult to break.
  
  
• Repellents do not eliminate browsing, only reduce it; therefore, repellent success is measured by the reduction, not elimination, of damage. If minimal damage is not acceptable, 8-foot fencing is the best option. Bird netting can be used to protect individual shrubs or small planting beds.
  
  
• Rainfall will wash off repellents, so they will need to be reapplied. Some repellents weather better than others. Generally, odor-based repellent products usually out-perform taste-based products. In general, it is unrealistic to expect more than 5 to 6 weeks of protection from any commercial repellent when you have high deer populations and browsing pressure during the dormant season.
  
  
• Repellents do not reduce antler rubbing.
  
  
• Repellents work by altering deer behavior. Therefore, they work best if used before feeding habits become established in a certain area. Deer establish their winter feeding habits in the late fall and spring.
  
  
• The availability of other, more palatable deer food dictates the effectiveness of repellents. When food is scarce such as during the winter or a drought period, deer may ignore both taste and odor-based repellents.
  
  
• A repellent that works in one area may not work elsewhere, even if the crop and conditions are similar to the first site.
  
  
• If you use repellents, do not overlook new preparations and products. New products are constantly appearing on the market. Learn about repellents by their active ingredients, not just by their trade name.
  
  
• Deer become accustomed to the same repellent and may learn to ignore the foul taste and odor. Alternating repellents on at least an annual basis will help to keep them confused and wary.
  
  
• Deer damage is an increasing problem and will be with us for years. Growers and homeowners who are facing long-term problems should compare the cost of repellents and fencing over many years. In many cases, it is more cost-effective to invest in a fencing system.

Applying a Commercial Repellent

Application methods for commercial repellents range from machine sprayers to manual backpack sprayers to handheld sprayers purchased at department stores. For large farms and commercial operations, machine sprayers are most economically efficient. The number of applications can be reduced by using compatible repellents (there are very few) in regularly scheduled pesticide programs.

Apply repellents on dry days when temperatures are above freezing and rain is not expected for a number of hours so they can dry properly. Whereas young trees should be completely treated, limiting repellent application to the terminal growth within reach of deer (6 feet above the deepest snow) can reduce the cost of treating older trees.

Repellent applications are divided into two general classes based on the time of the damage: 1) winter or dormant season, and 2) summer or growing season. Dormant season damage is most common in nurseries, orchards, forest seedlings, residential landscapes, and Christmas tree crops. It is most difficult to control due to the lack of other food sources. Growing season damage is most common in field and row crops. Apply repellents before the anticipated periods of deer browsing. The objective is to make the planted material unattractive to deer, so that they feed elsewhere. Once a feeding pattern has been established, repellents are usually less effective. It is important to note that if no alternative food source is available or if deer pressure is too high, even the best planned repellent program may fail. This is why it is essential to analyze your situation.

As a preventative measure, the first repellent application of a summer control program should take place within 2 weeks of bud break. During the growing season, repellents should be applied as necessary to protect new growth, usually every 3 to 4 weeks. For some crops, it may be possible to disrupt deer feeding simply by spraying a wide strip on the border of the planting. For dormant season protection, mid fall and early winter applications are recommended.

Regardless of the type of application program used, every program should be planned and implemented on schedule. Periodic monitoring is essential for determining the necessity and timing of subsequent applications.

• Repellents for use on edible plants - as a group these repellents tend to wash off quicker than contact repellents and may require special stickers such as Wilt Pruf, Latex 202-A, Vapor Guard, or Weathershield (known as anti-transpirants) to make them last longer.
  
  
• Repellents for use on non-edible plants -as a group these repellents tend to have formulas that make them stick to the surface to which they are applied. They are commonly used on ornamentals where long-term effectiveness is desired.
  
  
• Zone repellents -these are commercial products that are packaged in a hanging bag (saches) or are sprayed over the area to provide a scent that attempts to keep deer out of the area. Saches filled with soap or meat meal that putrefies with age are available commercially. There is a lack of research to indicate that these products are effective.

Table 1 - Repellents for Use on Edible Plants

These repellents wash off easily with rainfall and may require the use of an adhesive additive to increase longevity. Adhesives are a group of additives known as "anti-transpirants" that are added to the repellent mixture and increase its resistance to weathering. Some common trade names are: Vapor Gard, Weathershield, and Latex 202-A.

Mode of Action	Active Ingredient	Use on edibles	Longevity	Trade Names
Odor	salts / fatty acids	Yes (EPA label)	Washes off after heavy rain *	* Hinder * Deerbusters deer & rabbit repellent
Odor	garlic oil	Yes (EPA label)	Washes off after heavy rain *	* Deerbusters deer & insect repellent
Taste	capsaicin	Yes(EPA label)	After heavy rain *	* Miller's Hot Sauce
Odor	Predator urine's	Not directly (But can apply nearby to protect edibles)	30 days plus or minus	* Coyote and wolf urine (many companies offer products)
Odor Taste	Fish by-products and/or beef by-products	Not within 8 weeks of eating (Used as a growth stimulant with repellent properties secondary)	15-30 days *	* Bobbex * Deerbusters plant growth stimulant
* New growth requires application more often

Soap bars. Several recent studies and numerous testimonials have shown that ordinary bars of soap applied like hair bags can reduce deer damage. Hang bars of soap every 3 feet on vulnerable trees and shrubs. Leaving the wrapper in place, drill a hole in each bar and suspend it with a twist tie or string. As the bars weather away, they must be replaced. This method is labor-intensive, but many fruit growers claim it is an effective and economical control, espe-cially on very young trees. An inexpensive brand of soap will work. Some vendors sell ready-to-use bars.

Tankage (putrefied meat scraps). Tankage is a slaughterhouse byproduct traditionally used as a deer repellent in orchards. It repels deer by smell, which is readily apparent. To prepare containers for tankage, remove the tops from aluminum pop cans, puncture the sides in the middle of the cans to allow for drainage and attach cans to the ends of 4-foot stakes. Drive the stakes into the ground 1 foot from every tree you want to protect or at 6-foot intervals around the perimeter of a block. Place 1 cup of tank-age in each can. You can use cloth bags instead of cans. You may have to replace the containers peri-odically because fox or other animals sometimes pull them down.

Table 2. Repellents for Use on Non-Edible Plants. These are repellents designed to stick to ornamental trees and shrubs and provide a longer period of control.

Mode of Action	Active Ingredient	Longevity	Trade Names
Odor Taste	Putrescent egg-based	4-8 weeks*	* Deer-Away * Deerbusters deer repellent powder
Taste	Fungicide Thiram-based products	4-8 weeks*	* Bonide Chew-Not * Deerbusters deer repellent & turf fungicide
Odor Taste	Edible Animal Protein (bloodmeal products)	4-8 weeks*	* Plantskydd * Repellex * Deerbusters Deer2
Taste	denatonium benzoate or bitrex	4-8 weeks*	* Tree Guard * Ropel * Repel
Odor Taste	Some combination of the following: Putrescent egg-based, garlic, hot pepper, bitrex	4-8 weeks*	* Deerbusters Deer I * Deer Stopper II * Deer Off
* It is not realistic to expect commercially-available repellents to be effective for more than 4-8 weeks with high deer densities and browsing pressure commonly found during the dormant season. New growth requires application more often. Longevity will vary with environmental conditions and locations throughout the state

Considerations in Choosing a Specific Repellent:

Effectiveness and Longevity
Studies of the effectiveness of different repellents on nursery plant species and residential landscapes show large differences in all these factors (Tables 1 & 2). In general, it is unrealistic to expect more than 5 to 6 weeks of protection from any commercial repellent when you have high deer populations and browsing pressure during the dormant season. Protection may be longer when the conditions and seasonal factors are less severe.

Repellents can be effective for short-term forestry applications on seedlings that only need a few years of protection to grow out of the reach of deer. In agricultural applications, repellents may be suited to short-term crops such as strawberries or vegetables that only need protection during the growing season when other food sources are available for deer and they can be discouraged from frequently the target area.

Cost and Ease of Use
Repellents are not usually cost-effective in managing deer damage over a long period for either commercial growers or residential homeowners. Studies in New York have shown that the cost of a repellent spray program for reducing deer damage year round in orchards exceeds the cost of high-tensile deer fencing after only a few years. Money spent on repellent applications could be wasted if unusual weather conditions force deer to eat crops because of the loss of alternative foods.

Many residential homeowners are not as concerned as commercial growers about the cost factors and the use of repellents in residential landscapes is increasing. However, even residential homeowners will soon find that the long-term cost of repellents can be prohibitive and require repeated applications. Table 3 lists a representative list of repellents, their active ingredients, and the cost per ounce for different mixtures. Some repellents can be purchased as ready-to-use (RTU) or as a concentrate and then mixed with water for use as needed. In general, RTU products are more expensive per ounce than concentrates as indicated in the Table 3. Purchasing larger quantities of either RTU products or concentrates will also reduce the per unit cost. Ready-to-use products are easier to use than those that require mixing and are most popular with residential users. Some of the products have mixing requirements that make them difficult to use and may not appeal to some users.

Residential homeowners are increasing looking to the use of electric and non-electric fencing options instead of repellents as the realities of cost, marginal effectiveness, and regular application become apparent. Fencing may pose problems due to aesthetic considerations, local covenants, access, and other concerns, but these problems can addressed by educating community associations and neighbors. Many residential homeowners are finding the use of bird netting during the winter a reasonable alternative to the use of repellents. In the residential environment, there are large differences in the effectiveness and longevity of different repellents with similar costs. Users of repellents should ask their local cooperative extension office for current research on this topic.

References:

Curtis, P., P. Jensen, and K. Oliver. 2000. Relative Effectiveness of repellents for preventing deer damage to Japanese Yews. (In press)

Kays, J. 1997. Controlling deer damage in Maryland. Extension Bulletin 354. College Park, MD: Maryland Cooperative Extension.

Acknowledgments

Special thanks to Paul Curtis, Wildlife Extension Specialist, Cornell Cooperative Extension, Ithaca, NY, who graciously shared research data and his expertise. Thanks to his assistance, this publication provides information of great value.

Author: Jonathan S. Kays, Regional Extension Specialist - Natural Resources, Maryland Cooperative Extension

Information provided by Rob Berghage and Jim Sellmer
Penn State Department of Horticulture
Ornamental Horticulture Extension Specialist
103 Tyson Building
University Park, PA 16802
(814) 863-2571

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