10-15X magnifying glass or lens
Pest management systems cannot be implemented if a grower does not know which pests exist and whether populations are significant. Therefore, a scouting plan must be devised for each nursery. To be successful, scouting must be performed as routinely as any other nursery practice.
There are several prerequisites which must be satisfied to accomplish a successful monitoring program. An implementor of an IPM program must:
1. Commit enough time and sufficient money to expand pest control practices from dependence on pesticide to a truly integrated system.
2. Establish a procedure to decide who is going to make the pest management decisions.
3. Provide the scout or scouts with a 10-15X magnifying glass or lens, literature with pictures for proper identification of pests, white sheets of paper, a notebook or clipboard, data sheets, and pencils. In addition, small plastic vials with alcohol and plastic bags are very useful for storing samples of pests or damage for later laboratory identification. A good strong sweep net may be used to sample certain flying pests. A detailed map of the sampling area is required for adequate record-keeping.
4. Divide the nursery into logical units and then make maps of these units so all members of the IPM team can communicate pest and crop information uniformly.
5. Provide scouts with adequate training to allow them to identify pests in all life cycles.
6. Hire a consultant or professional scout if employees are already overworked.
Scouts must have common sense and an excellent knowledge of plants and pest biology including pest life cycles, natural enemies, damage, host plants and effects of extraneous risk factors, such as stress and injury. A good horticultural background and experience with the natural growth and appearance of plants will allow the individual to perceive unhealthy plants rapidly.
Monitoring should be performed weekly or preferably twice weekly during the entire production season. Scouts should enter each block of plant material looking for anything unusual in plant color; environmental conditions, such as standing water; or maintenance problems, such as torn plastic, malfunctioning sprinkler heads, etc. Walk at random through the area in a zigzag pattern and visually inspect about five percent of the plants. Check both new and old growth, but predominately the new growth. Examine both leaf surfaces for large insects and disease symptoms. Use the 10-15X magnifying device to facilitate observance of the smaller pests such as mites and thrips. During individual plant inspection, strike the foliage over a white sheet of paper or white paper plate to dislodge small pests, primarily mites and thrips, for easier viewing.
The use of yellow-colored sticky traps (cups, plates or cards), which attract and capture whiteflies, aphids, thrips and leafminer flies is a valuable aid in monitoring for early invasions and serves as an index of activity for these pests. Solo brand yellow plastic cups or plates that are available in grocery stores work just as well as sticky cards that are purchased commercially. Spread STP oil treatment uniformly over the cups or plates and place them on stakes just above the plant canopy. Check for insects stuck on the traps at least two to three times per week. Time counting insects may be saved by counting those within a one inch wide vertical column on the sticky trap.
Memorize the key identification characters for insects commonly caught on sticky traps
Aphids and thrips tend to be caught on the bottom half of the traps. Leafminer flies are caught more often along the top, and whiteflies tend to be spread uniformly on the trap. Since insects are not distributed evenly horizontally across the trap, columns counted should be vertically towards the middle of the trap. The traps should be placed in the same position each time to allow a true picture of insect activity to emerge. Place the traps in a grid-like fashion at least one per 1,000 square feet of production area. Sail traps for capturing male scales and mealybugs and double-sided sticky tape for capturing crawlers of these insects are also important monitoring devices. These traps should be placed on scale and mealybug susceptible plants to indicate when populations are primarily in the crawler stage and vulnerable to pesticide management. These monitoring devices can be homemade or purchased commercially. When certain common pests are detected on woody ornamental plants, all species susceptible to these pests should be monitored carefully at the same time to determine extent of infestation and damage.
At least 10 minutes should be spent in inspecting 20 or more plants for every 1,000 square feet of production area. Inspection starts at the bottom on the plant by checking at the soil level for insect pests or disease and proceeds upwards, looking at older leaves, young leaves and new growth. Containers should be tipped sideways for inspection of the undersides of the leaves. Scouts should become familiar with the key plant/key pest concept. These are plant species or cultivars that are almost always infested with specific pests at specific times of the year. Examples are as follows: azalea - caterpillars, lacebugs; crape myrtle - aphids; hibiscus - aphids, scales, whiteflies, spider mites; Indian hawthorn - wax scale, lacebugs; juniper - spider mites; magnolia - white magnolia scale; pittosporum - cottony cushion scale, aphids, spider mites; oleander - aphids, caterpillars; rose - aphids, spider mites, various beetles. Often such key plants have specialized pests, or are preferred cultivars.
Indicator plants are often used to good advantage. The first plant showing symptoms becomes an indicator plant. This plant is marked with a flag or in some manner that allows the scout to check the same plant every few days. Pests on this plant are monitored for population increases. Other highly susceptible plants that may be placed in the nursery as indicator plants and the pests they attract are as follows: tomatoes, lantana, gerbera daisy, pintas and poinsettias for whiteflies; marigolds, roses, ficus and hedera for spider mites; hibiscus, mums and roses for aphids; impatiens, hibiscus and gloxinias for thrips. Recording information on the pest life stages present will help with decision -making and better target controls to the most vulnerable stage. Counts or estimates of pest numbers can then be converted to the quantity per plant, statistics can be calculated and the results compared and discussed in a meaningful way.
Scouting information may determine that only small infestations exist and spot treatments may be appropriate. At this time, an effort should be made to determine if the pest population is increasing, decreasing or apparently static. Note the presence of natural enemies on the infested plants and record an estimate of the percent of the pest population in each life stage in relation to the sample unit. These data will help assess the risk of further damage and the pest population status. Immediate application of control measures is usually only cost effective for populations that are increasing.
Pest population dynamics relates pest population levels to thresholds and control actions. The important point is that the simple presence of pests (visual threshold) on plants does not necessarily indicate that control actions are appropriate. The action threshold is the pest population level which triggers a decision to prevent pest populations from reaching the anticipated aesthetic or economic injury level; the level at which the loss from pest damage exceeds the cost of control measures. In nursery plants, particularly marketable plants, this level is often extremely low or zero. For those plants not ready for sale, more damage may be tolerated and the economic injury level may be higher.
The vast majority of pest populations are held below threshold levels by plant and weather factors and natural enemies. Doing nothing now and deferring a control decision until the next sampling date is often the most cost effective option. Repeated sampling through time will allow the decision-maker to become familiar with the risk of damage from each pest under various cultural and management conditions. Intelligent handling of the risk appropriate to each situation is the essence of IPM philosophy and practice and is fundamental to economically sound, environmentally and socially acceptable decision making.
Proper records are critical to effective management. Record incoming plant material inspections, scouting results, sticky trap, sail trap, tape information and crop treatments. Make notes as to species of plant pests, plant cultivars infested and any extenuating circumstances that may be related to pest outbreaks. Some species occur more often in one season than another. For example, hot dry weather conditions are conducive to twospotted spider mite outbreaks, but southern red mites usually occur in the fall and winter months. Some pests are more often seen under very wet conditions, while other pest populations increase in response to any type of stress that affects the plants natural defenses.
All production inputs must be noted concisely and accurately. Managers trying to make a diagnosis of a problem without records are at a disadvantage and may overlook potential causes of the problem. Maps of the nursery showing where sticky traps, sail traps, tape and indicator plants are located should be maintained. Pest infestations can be noted on these maps so that movement of the infestations can be monitored. As the season progresses, developing pest trends will facilitate direction for pest management decisions.
Approximately two to five days following the application of controls, the treatment should be evaluated for efficacy. Records of the controls used and other pertinent information should be made available for future reference. Follow-up treatments should be prescribed as needed.
UF/IFAS has for sale the "Commercial Ornamental Nursery Scouting Manual" that provides information on entomology, nematology and plant pathology practices in the nursery. (See order form) The data record forms (Scout Records, Incoming Plant Material, Pesticide Application Log, asnd Yellow Sticky Trap log) referenced in this section are available as full-page samples in the manual and can be copied for printing.
