Implementing Landscape Plant Management Programs in Institutional and Residential Settings

The homeowner IPM program: organization and implementation

The primary objective of the homeowner IPM project was to develop and implement a program that homeowners could use to more effectively manage their lawns, shrubs and shade trees. As an educational program, the operational objectives included increasing the homeowner’s ability to (1) recognize the ornamental plants at the homesite, (2) identify the agents creating problems for those plants, (3) decide if and when pests needed to be controlled, (4) select an effective control tactic from available alternatives and (5) apply controls in a timely, safe and cost effective fashion.

The program was orgnized and implemented following earlier ones developed by Davidson and Gill (1,2), Davidson et al. (3) and Hellman et al. (6). The foundation of the program was the 100 participating homeowners in Montgomery and Howard counties. Community leaders arranged for interested homeowners to meet with program supervisors during the spring of 1982. Homeowners paid a $50 fee to cover the scouting costs associated with the program.

After homeowners enrolled, IPM scouts were hired. Scouts were selected from undergraduate students at Maryland who had excelled in plant care and pest management courses, such as Woody Plant Materials, Pests of Ornamental Plants, Plant Diseases, etc.

The scouts made a preliminary visit to each homesite. The result of this visit was a detailed landscape map that indicated the location and type of each shrub and shade tree at the site (Figure 1). Once the maps were complete, the scout visited each homesite biweekly from late May through August to monitor all plants for pests and cultural problems. Populations of beneficial insects were also observed. Plants with unknown causes of damage were sampled as needed. In addition to examining plants, scouts used other techniques such as pheromone traps to monitor pest activity. Furthermore, soil samples were taken to evaluate and correct nutrient and pH problems in the lawn and selected beds.

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Figure 1.

An example of a landscape map used in the homeowner IPM program.

Following each scouting visit, scouts met with supervisors to discuss remedial actions. Scout supervisors were county agents or graduate assistants at the University. Recommendations for most problems were made by the supervisor in consultation with the scout. However, problems that could not be solved at this level were forwarded to the University of Maryland’s Plant Diagnostic Clinic and other appropriate extension specialists.

When all problems had been discussed, each landscape map was annotated to show the location of each problem encountered and management options available (Figure 2). Accompanying the updated landscape maps were newsletters that summarized pest activity within the community and extension fact sheets that provided detailed information on specific problems. Homeowners received this information by mail usually within a week of the scout’s visit and incorporated it into a looseleaf binder provided at the beginning of the program. By the end of the summer, each homeowner had a personalized IPM guide of approximately 80 pages that could be used season after season.

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Figure 2.

An annotated landscape map sent to the homeowner following the scout’s visit. Location of pests and management recommendations are listed on the map.

During the latter third of the program, homeowners were surveyed by mail. The survey was a short questionnaire designed to evaluate how well the operational objectives of the program had been fulfilled.

Results and discussion

With respect to the operational objectives outlined above, we considered the homeowner project to be a success. Survey results indicated improvement in the homeowners’ abilitities to recognize their ornamental plants and identify the agents causing plant problems. Furthermore, the majority of homeowners believed that their ability to select the correct chemical controls and apply them at the proper time had increased. Most believed that they were more likely to substitute control tactics other than sprays such as pruning out pests as a result of the program. More than 80% of those responding to the survey felt that their ability to deal effectively with plant problems had increased and that they would save money and reduce pesticide use in the long run by adopting an IPM approach.

In addition to evaluating program objectives, we also surveyed homeowner willingness to participate in IPM programs offered on a commercial basis. Half of those responding to the survey said they would subscribe to a commercial IPM service.

Data gathered during the homeowner program have been compiled and summarized below. These results provide information on the type of plant materials being used, their tendency towards various problems, and the types of problems encountered. Extension and research entomologists at the University of Maryland are using this information to focus educational and research activities.

Plants encountered

A total of 5,855 individual plants and plant units (plants of the same species with coalesced canopies) were encountered in the 100 homesites. The 10 most common trees and shrubs are listed in Table 1.

These lists agree very closely with earlier lists published for suburban Maryland homesites (Hellman et al. 6). Differences in plants scouted reflect variation in characteristics such as the age and geographic location of the community.

During the 1982 growing season, 1716 plant problems, including those in lawns, were encountered in the 100 homesites monitored. The most common recommendation (43%) involved the application of chemicals to control the problem. However, 38% of the problems required non-chemical controls such as pruning, mulching, hand removal of pests or correction of water, nutrient, or pH levels. Nineteen percent of the problems required no action for reasons such as presence of natural enemies, or the lack of sufficient numbers or damage potential of the pest to warrant control.

When information on plant materials and types of problems are examined simultaneously, plant materials can be rated according to their likelihood of harboring problems. Table 2 lists the 5 most problem prone trees and the 5 most problem prone shrubs encountered in the 30 most common trees and shrubs. In contrast to the plants listed in Table 2, Table 3 lists the 5 trees and shrubs with the fewest problems of the 30 abundant plants. Trees such as peaches, apples, crabapples, cherries and dogwoods were beset with a great variety and number of insect, mite, disease and cultural problems. The same was true for pyracanthas, lilacs, boxwoods, roses and euonymus. Some plants such as peaches had multiple problems hence the percentage of plants with problems exceeded 100. Of the 1390 chemical and non-chemical control recommendations made for all plants during 1982, 520 or 37% were made for the 10 plants listed in Table 2 alone. These 10 plants comprised only 21% of the total plants encountered. Therefore, homeowners could greatly reduce time and money spent on plant maintenance by replacing these plants with others that would achieve the same effect or by using available cultivars that are more resistant or tolerant to diseases, insects and environmental stress. Greater consideration of the placement of plants at homesites would also help alleviate many problems.

Several commonly used shrubs such as yew, honeysuckle, and viburnum were almost pest free (Table 3). We found black gum to be an excellent native tree lacking insect, disease, and cultural problems. While black locust and tulip poplar are attacked by leaf miners and aphids respectively, they are trees least preferred by the gypsy moth, a serious regional threat to landscape plants. These plants probably deserve more attention in landscape design and construction.

Of the 1716 pest and cultural problems encountered, 53% could be attributed to insects and mites. Ten percent were caused by plant pathogens including bacteria, fungi, and viruses, while weeds accounted for only 2% of the problems. Nematodes were found killing a zoysia lawn at one homesite. The remaining problems could be attributed to cultural problems such as improper soil pH, fertility, exposure, etc.

The 10 most common insect and mite (arthropod) pests are summarized in Table 4. Several of the cateogries in Table 4 are groups of several pest species. The most common lacebug was the azalea lacebug. This pest was the single most common insect species encountered in 1982. Spider mites were the most common type of mite found. The abundant scale insects were euonymus, juniper and obscure scales, and the most common borers were the dogwood and peach tree borers and the oriental fruit moth. Important leaf miners included those on boxwood, arborvitae and birch. The most common aphids of import were on roses and the most common galls were those on spruce caused by adelgids. The primary weevil pest was the Japanese weevil.

Our findings agree well with results of previous homeowner programs (Hellman et al, 6). The majority of pests listed in Table 4 are now considered key pests or ornamental plants in typical suburban Maryland homesites. However, in situations where plant materials differ from those found at homesites, pest complexes will also differ. For example, the pests of large scale plantings at the University of Maryland, reported on later in this paper, are quite different than those found at homesites. Furthermore, Holmes and Davidson (7) worked with homeowners of a different socioeconomic class and found differences in plant materials and associated pests. A thorough study of the types of plant materials and their pests is vital to conducting any IPM program.

An Institutional Landscape IPM Program at the University of Maryland Campus: Organization and Implementation

The primary objective of the campus IPM program was to design, implement, and evaluate an IPM program for managing pests in a large scale landscape. The operational objectives included improving decision making regarding the need for control tactics, providing better selection and timing of controls, and reducing the amount of chemicals being applied by adopting practices such as spot sprays. By altering management practices we hoped to reduce economic and environmental costs associated with unnecessary or poorly timed sprays and yet maintain or improve the aesthetic quality of ornamental plants in the landscape.

The program was modeled after ones developed for homeowners by Davidson and Gill (1,2), Davidson et al., (3) and Hellman et al., (6). The University of Maryland at College Park occupies a 1300 acre site. The large size of the campus and the limited budget for scouting precluded the possibility for monitoring all the plants. Therefore, several high priority areas such as the Administration Building, Chapel, and Plant Nursery were selected by the Grounds Division to receive regular monitoring.

Each week all plants or plant units (clusters of the same species with coalesced canopies) were inspected for insect, mite, disease and cultural problems. When problems such as plant diseases could not be diagnosed in the field, plant samples were taken to the University’s Plant Diagnostic Clinic where identifications and control recommendations were made (extension specialists in Entomology, Botany, Horticulture, and Agronomy assisted in this process).

In addition to visually monitoring pest activities, pheromone traps were used to sample Japanese beetles, clearwing borers, and the gypsy moth. Data gathered from these traps served as a basis for timing chemical applications. Information gathered by the IPM scouts was summarized in a report. This report included control recommendations for the observed problems. Recommendations were based on pest populations and damage levels, densities of natural enemies, environmental and site conditions, and the landscape use and value of the plant. Plants with problems warranting control were indicated on a map (see Fig. 2).

Within three days of the actual scouting, written reports were given to Grounds personnel. Problems that required immediate attention were communicated verbally to maintenance people as rapidly as possible. Each week scouts and Grounds personnel met to discuss the findings of the scouting activities and to plan the spray schedule for the following week. The verbal communication was an important aspect of the management process.

Applications of chemicals were made by Grounds personnel and 1 of the 2 IPM scouts under their supervision. Although some treatments required the use of a large hydraulic sprayer, many were adequately administered with a backpack sprayer. Spot applications were used whenever possible.

Results and discussion

Conclusion

The accomplishments of the homeowner and institutional landscape IPM programs may be viewed at several levels. First, we have demonstrated that the IPM approach can be implemented in small and large landscape systems such as homesites and institutions. Second, participants in both programs believed that they were able to deal more effectively with their plant problems as a result of the program. Homeowners felt that they would save money and reduce unnecessary pesticide application with an IPM approach. Similar changes in pesticide use patterns were seen on campus. A third and vital benefit of these programs has been the production of highly trained plant care personnel. The students trained in these programs have moved on to jobs as arborists, research technicians, institutional pest control supervisors, and private consultants. Finally, these programs along with their antecedents and descendents, are generating a much needed data base documenting the occurrence and status of pests in the mid-Atlantic region.

The introduction to this paper lists several elements basic to an IPM program. Many of these elements such as information sources, control tactics and hardware are available and in widespread use in the plant care industry. However, other aspects such as the regular monitoring of pest populations and those of beneficial insects are not widely used. Progress in developing decision-making guidelines for the major pests of ornamental plants lags far behind the progress made in agronomic systems. Compounding this problem is a devastating lack of detailed information regarding the biology and ecology of the major pests or ornamental plants. Although preliminary IPM programs can and should be designed, implemented, and demonstrated in suburban settings, maximum benefits will not be realized until basic research needs have been fulfilled. Unless priorities shift in sources of funding for ornamental plant IPM or new sources become available, we believe progress in these areas will be slow. Despite these obstacles, we firmly support IPM as the most rational approach to managing the pests and problems of trees, shrubs, and turf in suburban systems.