B.C. Pest Monitor — Former Newsletter of IPM in British Columbia
Vol. 2 No. 1 May 1993
Developing IPM on Pears in British Columbia
Linda Edwards, Integrated Crop Management Inc., Okanagan Centre, B.C.
Until four years ago, a typical pest control program in most pear orchards in the Okanagan and Similkameen Valleys was based on up to 14 different sprays and cost approximately $1,200 per hectare for materials and application. As early at 1986, however, it was apparent that pear psylla, which is considered to be the key pest, was becoming resistant to synthetic pyrethroids and fungicide (Dithane) sprays. By 1989, resistance in pear psylla was a major problem; most pear orchards suffered severe defoliation and fruit in many blocks was so badly damaged that it was not picked that season (honeydew produced by pear psylla drips onto leaves causing them to turn black and drop; it also stains fruit). In 1987, some growers had begun working with our pest management company to find a solution to their diminishing control over pear psylla. We felt that predators should be studied for psylla control based on observations of organic pear orchards where psylla were seldom a problem because they were suppressed by native predatory insects. The organic pears, however, usually had levels of damage equal to the conventional orchards from other pests, such as codling moth, leaf roller and fruitworm. In 1990, the pear growers helped to obtain the funding we needed to start looking for some solutions. The project began in the winter of 1990 and the research and extension work has been conducted in growers orchards throughout the Okanagan and Similkameen Valleys for the past three years.
Objectives
The pear IPM project had three goals:
1. Augmentation of pear psylla predators.
Research explored the potential for collecting or rearing and releasing lacewings, ants, earwigs and Deraeocoris brevis (a native predatory bug).
2. Development of a predator compatible control program for other pear pests.
We needed to find effective controls for two-spotted mites, codling moth, Campylomma, leafroller and others, that were not destructive to the predator complex.
3. Grower education and involvement.
It was important to develop a program that we were sure growers would use because a predator-based control program, using monitoring and economic thresholds, was a radical departure from what they had been doing in the past.
Results
Of the predators investigated for augmenting natural populations, the earwigs and Deraeocoris were the most successful. Useful numbers could be reared or collected and they were effective pear psylla and mite predators. Campylomma (a mirid bug originally thought to be a pest of pears) was added to the list when it became obvious that it was an important part of the complex of predators required to control pear psylla. As it turned out, naturally occurring predators repopulated all sizes of pear orchards faster, and appeared in higher numbers, than we imagined possible. The predator complex functions well most of the time in most orchards, however, gaps do occur when predators are fewer than needed or when sprays are applied that are detrimental to them. Although we continue to look at augmenting natural populations by introducing predators, our focus has shifted to improving the habitat for the naturally occurring populations. This includes providing shelters for earwigs, planting alternate host plants for Deraeocoris and Campylomma and improving timing of sprays for other pests so they can be applied without killing predators.
In 1992, the pear pest management program used by the majority of growers in the 41 orchards we monitored, averaged 6 spray operations for the season, costing approximately $500 per hectare (see box). Dormant oil was applied in most orchards to prevent psylla egg laying and to control red mites. About 44% of growers did not need a pre-bloom spray of endosulfan (Thiodan) for psylla. Organochlorine pesticides (such as endosulfan and dicofol) do not appear to be destructive to Deraeocoris and Campylomma, therefore can be used in our predator-based program. Thiodan can also be used for curculio and green fruitworm if they are present in significant numbers. If monitoring shows that pear psylla numbers are too high at the pink stage of bloom, chinomethionat (Morestan) is used. We use sulphur (Kumulus S) for powdery mildew; it is much cheaper and less likely to damage fruit than other fungicides. Kumulus is also used by some growers instead of dicofol (Kelthane) for rust mites. Spider mites are no longer a problem under this program. Most growers use two sprays of phosmet (Imidan) for codling moths and about a third of the growers used mating disruption with pheromones. The large-scale sterile insect release program to control codling moths in the Okanagan should take care of this pest in the near future. Insecticidal soap sprays are still needed occasionally to keep the fruit clean. Leafrollers are the main problem now in many orchards and azinphos-methyl (Guthion) is the only really effective control. This chemical is very destructive to most psylla predators, however, we have identified windows in time when it would have the least impact on predators and are working on a program to assist growers in monitoring for, and timing, this spray.
Adoption of the "soft program" of reduced pesticide use in the pear industry was promoted by conducting the research in the pear orchards, giving weekly workshops throughout the valley, engaging in one-to-one consultations with growers, publishing newsletters and working with horticulturalists and field people.
In 1990, pear psylla control in 80% of the acreage was rated as greatly improved to excellent. There were further improvements in pear psylla and spider mite control in 1991 as more of our time and energy shifted to investigate other pests. The 1992 crop was the cleanest in 25 years. Over 90% of the growers have now adopted the "soft program". We were able to convince the marketing agency for 70% of the growers to try marketing part of the 1992 Anjou pear crop as an IPM product.
Success Factors
Several factors contributed to the success of the project. One factor was that we worked with the whole system instead of one pest at a time. We feel that examining many relevant factors and finding simultaneous solutions gave us a workable program within a relatively short period of time. Grower involvement was also fundamental to success. Growers made their orchards available and helped with, and also conducted, experiments. They gave us ideas, support and feedback on the practicality of what was being done and they learned how to make the new program work in their own orchards. Another factor in the success was the extensive and long-term monitoring conducted in many different orchards. Seven pear orchards were monitored weekly from early spring until the pears were harvested for three years. From 40 to 50 other pear orchards in both valleys were also monitored bi-weekly during key times of the year for the same period. This provided the wider context to enable us to evaluate what we were seeing in our experiments. For example, our pear rust mite experiments indicated that, at current levels, neither pre-bloom nor post-harvest control programs had a practical impact. This was validated by the experience of many growers in both valleys carrying out a variety of pear rust mite experiments and control programs.
This project relied on harvest results, such as information from bin checks, packing house records and evaluations by growers as much as on experimental data to assess progress and determine direction. The research program was flexible and evolved with the changing needs of the program. For example, two-spotted mites essentially disappeared by the second year and experiments on controlling them were discontinued. Leafroller and rust mites problems, however, increased greatly, so more time and energy was shifted to them. It is important that a pest management system remain flexible, with on-going monitoring, to respond to problems such as increasing pesticide resistance and the appearance of new pests, such as curculio, a weevil that became a problem in some orchards.
The new pear pest management program is not one set recipe which can be applied in every block, nor will it remain unchanged from year to year. However, with better monitoring and adaption it should serve the pear growers longer and better than a program based on chemical pesticides.
Apple Pest Management in British Columbia
Hugh G. Philip, Entomologist, BC Ministry of Agriculture, Fisheries & Food, Kelowna, B.C.
Although the term integrated pest management (IPM) is relatively new to the vocabulary of most apple growers, the idea of replacing or reducing chemicals through the introduction or preservation of biological control agents dates back to the 1930's in B.C. The first attempt involved releases of imported parasites to control codling moth. This was followed by research into biological control of apple mealybug, woolly apple aphid and oystershell scale. Acceptable control was achieved for all except the codling moth. Because growers were forced to rely on available, broad-spectrum chemicals to control this devastating pest, others, such as European red mite, McDaniel mite and two-spotted spider mite became serious pests as their natural enemies were killed by nonselective insecticides.
In the 1960's, pest resistance to chemicals and increasing public and scientific concern about the environmental and health hazards of these chemicals stimulated research into alternative methods of control. Under the leadership of scientists at the Agriculture Canada Research Station in Summerland, significant advances were made in the development and implementation of IPM practices. These included integrated mite control programs, using sterile insects for codling moth control, pheromone traps for monitoring codling moths, and the recognition and documentation of the impact of natural parasites and predators on pear pests. Extension entomologists and horticulturists of the B.C. Ministry of Agriculture, Fisheries and Food (BCMAFF) worked closely with the research staff and growers to promote the adoption of these new pest management methods. The following article describes the current use of IPM in apples and new developments that should be in the hands of B.C. apple growers in the very near future.
Mites
Today, all B.C. apply growers use IPM techniques to some degree to protect their crops. Since the introduction of integrated mite control and leaf brushing services to monitor pest mites and predatory mites in the late 1960's, growers have significantly reduced the number of miticide treatments. Indeed, most apple growers have not had to spray for mites since adopting this integrated approach to mite control, which is basically a biological control program that relies on native predatory mites. When miticides are necessary, growers avoid disrupting mite programs by using selective miticides that kill only plant-feeding mites and are relatively harmless to predatory mites. The most abundant species of predatory mites are also tolerant to the most commonly applied insecticides so, with care, growers may use chemicals to control other pests as required without causing secondary mite problems. To minimize the impact of other chemical pesticides on predatory mites, the lowest effective rates of most insecticides are recommended and growers are cautioned about the use of certain insecticides harmful to predatory mites.
Codling Moth
The codling moth IPM program has been used by ever-increasing numbers of growers since the 1970's. The program involves monitoring daily maximum and minimum temperatures to calculated day-degrees (see box). Insecticides are applied only once a predetermined number of day-degrees are accumulated, but only if the number of male moths captured in pheromone traps in the orchards is above a predetermined action threshold. Otherwise, no sprays are applied. Growers monitor temperatures and conduct moth counts themselves or they contract to have it done by their packing house field service or by a private pest management consultant. Through the use of this monitoring program, growers have been able to reduce spray costs by spraying only when and where necessary. It is estimated that the introduction of IPM programs for mites and codling moths have reduced the amount of insecticide and miticide applied in the B.C.'s interior apple growing regions by up to 60%.
With the official opening in January 1993 of the mass-rearing facility in Osoyoos (jointly funded by the provincial and federal governments), the codling moth sterile insect release (SIR) program is underway. Over the next ten years, sterilized moths will be released in apple and pear orchards in the Creston, Okanagan and Similkameen valleys to mate with "wild" codling moths. Because no fertile eggs will be produced from these matings, the program is planned to breed the codling moths into extinction.
In the past two years, many growers have used a novel experimental control method, known as mating disruption or pheromone confusion, to prevent codling moth damage. Normally, male moths find females by following an odour trail of sex pheromone given off by the female to attract mates. Mating disruption involves hanging a large number of twist-tie dispensers containing synthetic female sex pheromones in trees throughout the orchard. Male moths cannot find female moths in these orchards because the air is saturated with pheromone, thus no mating occurs. Dispensers are effective for several months, therefore most growers need only apply one spray early in the season and the pheromone dispensers take care of codling moth for the rest of the summer.
Other Caterpillars
The reduction or elimination of codling moth sprays has allowed other insects such as leafrollers and eye-spotted bud moth to escape control and cause more fruit damage. One species, the fruit tree leafroller, has developed resistance to the sprays that once controlled it in one area of the Okanagan Valley. Sprays of BT (Bacillus thuringiensis), a biological control for caterpillars, are now used by many growers to control resistant leafrollers. Other growers use BT instead of conventional insecticides to control leafrollers and other caterpillars.
Successful control of fruit tree leafroller requires proper timing of treatments, especially for products like BT At present, growers are encouraged to monitor egg hatch in order to improve timing of their treatments. Agriculture Canada scientists in Summerland are going a step further by adapting a method of day-degree accumulation for predicting when leafroller eggs hatch. Growers need only record temperatures (manually or with automatic recording devices) instead of spending time looking at egg masses. Also, a blend of sex pheromones has been developed that shows promise in mating disruption of four important leafroller pests. Research on the application of this method for eye-spotted bud moth also shows promise.
Mullein Bug
Cooperative research between Simon Fraser University and Agriculture Canada Summerland is close to providing a method for growers to better time the application of control treatments against the mullein bug (Campylomma) by using day-degree accumulation. A pheromone has also been discovered that will be useful in detecting mullein bug populations that may pose a threat to apple crops.
Scales and Other Pests
Using dormant oil sprays (highly refined oils that are applied before leaves appear) in the early spring to control San Jose and European fruit scale, mites and aphids eliminates the need for post-bloom sprays that would harm important beneficial insects and mites.
Tentiform Leafminer
A recent migrant into B.C., the tentiform leafminer, has brought with it a parasitic wasp species that, if left alone, will keep leafminer numbers below damaging levels. Unfortunately, the long growing season in 1992 allowed leafminers to build up to damaging numbers in some young apple orchards, which reduced fruit quality and tree growth. The good news is that BCMAFF field surveys found parasite populations also increased dramatically over the season and that an average 80% of leafminers were killed by parasites before leaves started to fall. Thus, it is expected that the leafminer will once again be held in check by its parasites in 1993.
Conclusion
The apple industry has struggled through some tough economic times over the last decade. Growers are seeking not only pest management methods that are effective and compatible with their crop management system, but are also more environmentally friendly. IPM is cost-effective as it allows the growers to not only minimize potential risks to the environment, but also to widen the margin between production costs and product sales by reducing crop protection costs. Many growers have found that savings derived through IPM more than pay for the services of pest management consultants. With the advances being made in controlling apple pests, it is not unreasonable to expect that all apple growers, as well as other fruit growers, will soon be able to market fruit that has not received an application of synthetic insecticide or miticide.
Nematodes vs Fungus Gnats
Dr. Michelle Gorman, IPM Coordinator, Victoria City Parks
Due to the moist conditions in one of the Victoria City Parks greenhouses, fungus gnats have been an on-going problem, which has been dealt with in the past by applying petrochemical pesticide drenches. We started using insect parasitic nematodes when adult gnat levels reached moderate populations of an average of 29 gnats per yellow sticky trap. The product (BioVectorreg.) was applied at a rate of 1 jar of product to 1000 L of water, using a 1% dose metric fertilizer injector. This was watered into 8,000 geraniums, 2,000 begonias and 300 miscellaneous other plants. Nematodes were checked for viability by eye or by microscope and an application rate of approximately 11,250 nematodes was delivered per 4 inch (ca. 10 cm) pot (this was determined by counting the number of nematodes collected per cm3).
Two weeks after the first of three weekly applications, the fungus gnat population was reduced from a total of 595 adults trapped in the greenhouse to 284 adults. Gnat populations levels continued to stabilize over the next few weeks. Among the advantages of treating fungus gnats with a biological control agent like BioVector is the ability to handle the plants after they are treated. In a nursery operation, when cuttings are being taken and stock continually moved, this can be quite an important advantage.
Bluebirds vs Grasshoppers
Peter Fofonoff, Senior Agrologist
BC Ministry of Agriculture, Fisheries and Foods
Williams Lake, B.C.
A fifteen year old program to increase local Mountain bluebird populations in the Cariboo-Chilcotin region has been successful, with bluebird populations increasing dramatically. Bluebirds are a major predator of Orthoptera (mainly grasshoppers). Reports by C. Herlugson in 1982* indicated that Orthoptera made up 58% by weight of food fed to nestling Mountain bluebirds and 37% of the food of adults in south-central Washington. The objective of the program, therefore, is to increase the bluebird numbers and, in turn, reduce the grasshopper populations. In cooperation with Williams Lake Field Naturalists, over 1500 nest boxes were placed in high infestation areas. Although the direct impact on grasshoppers is difficult to determine, there is no doubt of the success of the nest box program. A survey in 1991 found that 75-90% of the nest boxes were being used by bluebirds, depending on the location. Other non-chemical controls for grasshoppers are being investigated by Agriculture Canada researchers, such as naturally occurring fungi (Beauveria bassiana).
*1982. Murrelet. 63:59-65.
Publications
Books
Knowing and Recognizing. 1992
M. Malais & W. J. Ravensberg
This is an in-depth technical manual on using biological controls for a variety of pests found in vegetable and ornamental greenhouses. Excellent photographs and illustrations as well as detailed information on the biology and life cycles of pests and beneficial species make it a good reference guide. It should be useful to commercial greenhouse and interior plantscape managers as well as anyone interested in a better understanding of biological control. References. 109 pp.
Available from: Safer Ltd., #1-465 Milner Ave., Scarborough, Ont. M1B 2K4
Ph: 1-800-387-5306 Fax (416)-291-1755 Soft cover $34.95 plus 7% GST
Pamphlets, Guides, Fact Sheets
Broom and Gorse in British Columbia: A Forestry Perspective Problem Analysis. 1992
Recently, forest managers and the public have become concerned about the competitive abilities of broom and gorse. This report investigates the extent of broom and gorse in B.C., their impact on crop trees and other non-timber forest resources, and their control.
This report and other forestry fact sheets are available from:
Attn: Debora Tarry Ministry of Forests, Silviculture Branch, 990 Fort St., Victoria, B.C. V8W 3E7
Fax: 604-356-6052 No Charge.
Safe and Sensible Pest Control. 1991.
By L. Gilkeson
Just off the press is a new title in the series of guides developed by B.C. Environment to encourage the use of safe, practical alternatives to the overuse of pesticides to control common pests of home and garden.
New title: Rats and Mice
Other titles still available: Fleas, Yellowjackets, Aphids, Turf Weeds, Beneficial Insects, Carpenter Ants, Household Insects. (see brochures on this web site).
New Products
Products and services are listed for reader information only. This does not constitute an endorsement of either quality or effectiveness by B.C. Environment.
Information Service
Expert Access Services in Victoria has been established to provide information services to people in the parks and recreational field. The service carries books, videos, brochures, reprints of articles and other relevant publications for parks and landscape managers.
Catalogue available from:
T. J. Richards, 1464 Brooke St. Victoria, B.C. V8S 1M3
Ph. (604) 381-5256 Fx (604) 381-5256
Slow release fertilizer
Dawson Seed carries a slow-release organic fertilizer, Ringer Turf 10-2-6, which is reported to provide uniform, long-lasting turf quality with less clippings than urea treated turfgrass. The product contains hydrolysed poultry feather meal, bloodmeal, wheat germ and bone meal as nitrogen sources.
For more information:
Dawson Seed Co. Ltd, 17802 66th Ave., Bldg. "B", Surrey, B.C. VS 7X1
Ph. 1-800-267-8633 Fx 604-576-8634
Beneficial Insects
A new retail program called BioBugsTM has been launched by Safer Ltd., to sell beneficial insects and mites to home gardeners. Rather than purchasing these highly perishable living organisms at a garden centre, the customer pays for a voucher card for the beneficial insect product. The customer mails in the card and the bugs are sent by prepaid first class mail or collect courier directly to the customer. This ensures better survival of the insects and makes it possible for garden centres to make the full range of 7 species available in the small amounts needed in home greenhouses and gardens. Controls are available for: aphids, mealybugs, whitefly, spider mites and other pests.
BioBugsTM are available at many garden centres in B.C.
For more information:
Safer Ltd., P.O. Box 186, Station D, Scarborough, Ont. M1R 5B5
Ph: 1-800-387-5306 Fx: 416-291-1755
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