IPM advocates integrating as many suitable pest management practices as possible.
At the farm level, IPM is approached as a series of activities that culminate in a decision made by the grower. The first activity is gathering information about the environment, pest, and crop. This activity is termed scouting, or monitoring, and is performed frequently during the growing season. In scouting the grower assesses the growth status and general health of the crop and determines the presence and intensity of pest infestations or the potential for future pest problems. The resulting data are entered into a record-keeping system such as a notebook or computer data base.
The next activity is comparing pest levels noted during scouting with threshold values. Thresholds may be economically determined when the damage to the crop caused by a given pest population is compared with the cost of implementing a control procedure against that pest. If pest damage is higher, control is warranted. Other thresholds may be used depending on the desires of the fruit grower.
Once an over-the-threshold determination has been made, a control tactic or set of tactics can be selected and used. Tactics include biological control (using one organism to control another by predation, parasitism, or competition); cultural control: using horticultural practices such as planting disease-resistant cultivars, specialized pruning, and orchard sanitation; and behavior modification, such as mating disruption. The success of the control tactic should be assessed at a later date, usually the next monitoring period, and corrective action taken if necessary. All IPM activities should be permanently recorded so they can be used for making decisions in subsequent years. Increasingly, spray records are necessary for GAP, PRIMUS, and eco-label certifications to document pesticide use patterns and possible residues on fruit for export.
Some IPM practices should be performed in anticipation of future pest problems. These include pruning and shaping the tree to improve air circulation and prevent disease, selecting cultivars resistant to various pests, and managing the orchard to be hospitable to beneficial organisms, such as the mite predator Typhlodromus pyri. Other IPM practices occur after the growing season. Fruit from the orchard at harvest time represents a cumulative record of insect and disease activity for the season. This record can provide valuable insight into how well an IPM program is working and what changes in the program need to be made the following year. A sample of fruit from each orchard block should be inspected, insect and disease damage identified, and a written record made. The grower can refer to this record in subsequent years to make decisions about insect and disease control.
Basics of Insect Monitoring with Sex Pheromone Traps
The presence (or absence) of insects pest species in the orchard can be detected and monitored by a wide variety of traps and/or other methods, but the utilization of traps with an insect sex pheromone is probably the simplest and, at the same time, the most accurate way to monitor insect pests. Although multiple designs of traps work best for various pests, the general principle of how the average trap works is almost always the same: each trap needs to have a source of pheromone or attractant (usually rubber- or plastic-based lure/septa with incorporated sex pheromone and/or attractant), means to capture visiting moths (usually floor or liner coated with nondrying glue) and some kind of plastic or paper dome to protect the lure and floor.
The pheromone traps can be used to monitor insect species that are able to release pheromones. Most lepidopteran insects (moths and butterflies) produce pheromone to improve the ability of one gender individuals to find the individuals of the opposite gender. As long as the sex pheromone for the species is identified and can be manufactured, there is a possibility that pheromone traps can be used for monitoring of this species. And although the pheromone traps are a great tool for insect monitoring, they will not control insect pests. In our specific orchard ecosystem, traps are competing with the female moths in attracting male moths, but since normally there are a lot of more wild moths than traps, there is a strong possibility that mating occurs anyway and female moths will still be able to deposit viable eggs. Therefore, traps are excellent tool for moths monitoring but by themselves will not control the pest(s).
In Pennsylvania orchards, numerous pests can be responsible for injuries in fruit orchards. The importance of various pest species fluctuates from year to year, but almost always the most important pests will be part of leafroller complex with tufted apple bud moth (TABM), obliquebanded leafroller (OBLR), internal fruit feeders complex with Oriental fruit moth (OFM) and codling moth (CM), or borers such as dogwood borer or peach tree borer. Fortunately, with the current emphasis on practical implementation of IPM methods, the sex pheromone traps for all of those species are available for a purchase.
A single trap should be used to monitor only a single insect species. In properly monitored orchard, at least two traps per species should be used per block. In larger blocks--more than 20 acres--at least one trap per every 10 acres should be employed. It is important that traps within each block be placed in such locations that they would be able to provide accurate readings of moth pressure. Placing traps too far away from, or close to, possible moth sources such as large bin piles and abandoned or neglected orchards may provide inaccurate image of actual pest pressure. In orchards where only the absolute minimum trapping program is to be implemented, and traps will be used only to provide information about the best timing for insecticide applications, at least two traps per species have to be used per farm.
Pheromone traps should not be placed closer to the border of the blocks than on second to third row/tree from outside of the orchard. All traps placed in the orchard should be easily accessible by the person who will monitor them. The optional height for trap placement on the tree is at about 5 to 7 feet from above the ground, although traps for some pest species, especially codling moth, should be placed in the upper fourth of the tree height. For this higher placement, traps can be attached to bamboo posts and elevated into the upper part of the canopy. All traps should be placed within a tree canopy, not outside the tree. To make it easier for the person who will monitor traps during the season, traps for different pest species can be located on adjacent trees. It also may be helpful if the trees and tree rows with the traps will be marked with contrasting flagging tape.
The pheromone-loaded septa attracts moths only for a set period of time, usually from 4 to 8 weeks depending on the lure specification. In order to maintain reliable pest monitoring, the lure needs to be replaced before its attractiveness starts to deteriorate. Usually, the manufacturer provides the information for how long a lure will be active in the orchard. The glue-coated floors or liners also need to be replaced regularly, especially if high numbers of moths are being collected regularly and the glue layer is no longer sufficient to capture moths. In contrast to lures, which cannot be reused, the liners after cleaning and coating with new layer of glue can be reused in traps. It is very important that the reusable liners be used only in the traps for the same species as they were used previously.
Insect pheromones are species specific, and each species use a different set of chemicals to attract individuals from the opposite sex. Therefore, unless the trap (or the lure) is contaminated with some other pheromone specific chemicals, only the addressed species should be encountered in the trap. Of course, various colors of the traps can also attract other insects by visual attraction, but the presence of other insect species in the trap most likely will be incidental and/or sporadic.
With the yearly estimated price of monitoring system for one species (2 traps, 10 lures, 10 liners) circulating around $40 to $70 (without labor), the traps will pay for themselves in no time. A vigilant monitoring system should help growers avoid problems with unexpected occurrence of pests in the orchard. Even, as a result of pest monitoring, additional insecticide application will be necessary to manage detected problem, dealing with the infestation before actual fruit damage occurred seems to be a much better approach than dealing with injured fruit at harvest.
Unfortunately, in our Mid-Atlantic fruit region, a number of other common pest species such as stink bugs, apple maggot, plum curculio, European apple sawfly, or various plant feeding bugs also can create a serious threat to fruit. This group of pests does not have a good pheromone-based monitoring system; however, other trapping/monitoring methods using other means such as visual or food-odor-related clues are also being used for pest detection. It is very important that growers monitor these pests as well.
Even though the best designed and most complete monitoring program will not eliminate the insect problems from the orchards, such activity will certainly help to better manage fruit pests.
Source: Penn State Tree Fruit Production Guide