IPM in Raspberries A Guidebook
Craig MacConnell, Washington State University Extension, Whatcom County
(copy of a talk presented at the 2000 meeting of the Lower Mainland Horticultural Improvement Association, Abbotsford, British Columbia, permission to post)
Washington State University Extension, Whatcom County received an EPA Clean Water Act, Section 319 grant in the spring of 1995 to assist the agricultural community in the adoption of an Integrated Pest Management (IPM) approach to solving pest problems in the Nooksack watershed of northwest Washington. This 3-year long "Nooksack Watershed IPM Project" targeted raspberry and apple growers. The major goals were to increase IPM awareness in the agricultural community and to adopt crop specific IPM practices that will stay with the agricultural industry. A major educational product of the program was the completion of a manual titled: "Integrated Pest Management for Raspberries - A Decision-Making Guide for Key Raspberry Pests in Northwest Washington".
The project, and ultimately this manual, had broad support and direction from growers, researchers, extension personnel, farm supply companies and community leaders from both Whatcom County and Lower Mainland, British Columbia. The format of this guide is very useful for growers because sampling procedures and decision-making guidelines are organized chronologically based on crop stage and pest development. This manual has been distributed to over sixty people in the region. We are particularly proud of the insect and disease identification sheets. Many of the images used were provided by researchers affiliated with Agriculture and Agri-Food Canada. Our primary focus is to distribute it to growers, but it has also been well received by farm supply companies, university research and extension agents, as well as organic berry farms. The manual is available in both a 3-ring binder format and as a CD-ROM for computer use. It can also be viewed on the internet at: http://whatcom.wsu.edu/ag/comhort/nooksack/ipmweb/Toc.htm
This presentation focused on sampling methods and decision-making for key pests at each of four crop stages as organized in the manual and summarized below by each of these crop stages.
Delayed Dormant to Bud Break (Late March to Mid April)
Clay-colored weevil, 0dorhynchus singularis.
- Cool spring weather can delay floricane bud break and increase damage potential
- Sample with a 16" X16" beating tray, 10 samples per site, 3-5 sites/field on two occasions from late March to mid April, preferably at night in early season.
- Research on Meekers in 1999 in Lynden documented 20-30% bud damage with average of 30 weevils per 10 trays during April. This represented a crop loss of approximately 1 ton/acre or 25% yield reduction in research plots where weevils were allowed to feed for 3 to 6 weeks through April and into early May.
- We are currently recommending an action threshold of 2-3 weevils per 10 tray samples.
- Lower canopy (lower 3-4 ft above hills) applications of bifenthrin (Brigade) have provided equal clay-colored weevil control compared to full canopy sprays and do so with less total pesticide applied.
- Applications made in mid-April kill weevils prior to the onset of egg-laying which appears to begin in early May.
Cane Disease Management
- Important time to survey floricanes to determine the degree of infection from spur blight, Didymella applanata, and cane blight Leptosphaeria coniothyrium.
- Cane blight is less common, but when detected in a field, consideration should be given to fungicidal treatment immediately after harvest, particularly if the harvest season has been a wet one. Scraping bark away above physically damaged buds at catcher plate height will reveal red streaking up the cane in cane blight-infected floricanes.
- On-farm research over the past few years has confirmed the value of delayed-dormant liquid lime sulfur for reducing incidence of both yellow rust, Phragmidium rubiidaei, and spur blight.
- Experimentation with delayed applications of Sulforix applied at half the normal rate have provided improved control of these cane diseases compared to standard timing but is not currently recommended due to phytotoxicity concerns and labeling restrictions.
Pre-Bloom to Early Bloom (Mid April to Late May)
Western Raspberry Fruitworm Beetle, Byturus bakeli
- Larval stage is potential fruit contaminant
- Sample adults twice in early and mid April using beating tray and 5-minute bloom search.
- Detection warrants treatment in IQF fields. No economic threshold developed.
- Have been effectively controlled with single, diazinon application prior to bee placement.
- Populations are highly variable from year to year.
- Critical period to observe primary infection (aecia) on foliage from overwintering stage.
- Look closely at foliage at wire height for yellow pustules on upper leaf surface in mid to late April.
- This sign of the disease is associated with leaf debris trapped at the wire.
- Apply fungicides, if available, where incidence of aecia is high to protect foliage from aecia spores and repeating secondary infections of foliage
Obliquebanded leafroller, Choristoneura rosaceana, is of secondary importance in most fields in Whatcom County due to prevalence of bifenthrin (Brigade) use as a "cleanup spray". Late June application corresponds to peak first generation moth flight and likely controls many adults and early emerging larvae.
- Some growers use Bacillus thuringiensis products to control overwintering caterpillars in April and May as needed and pheromone traps are employed in mid-May. Trap catch data does not clearly correlate with in-field larval populations. Orange Tortrix is a significant threat in Skagit compared to Whatcom County.
- Pheromone traps in place since early April should be checked and cleaned regularly due to high trap catch potential.
- Summer emerging, first generation caterpillars usually appear in mid-June or thereabouts, so sampling should focus on leafrolling at that time.
Adult black vine weevils,Otiorhynchus sulcatus begin emerging from the soil in early to mid-May. Research with spur blight spore trapping in Lynden has confirmed that in most years, mid to late May is key timing for first fungicide applications to control spur blight. This timing is well synchronized with the first protectant spray targeting botrytis fruit rot, Botrytis cinerea, during early bloom.
Late Bloom through Harvest Period (June to Mid-August)
Predominant harvest-contaminating species are black vine weevil, rough strawberry root weevil, Otiorhynchus rugosostriatus, and strawberry root weevil, Otiorhynchus ovatus.
- Adult black vine weevil soil emergence and egg-laying has been well-studied in Lynden during the past few years. It is thought that the other most common summer-emerging weevils have similar phenology.
- A full canopy pre-harvest (late June, early July) bifenthrin application is commonly used as a broad spectrum insecticide to control harvest contaminating insects. This material is very important in machine-harvested raspberries, allowing growers to produce a practically insect-free product.
- This timing follows the completion of most species' adult emergence from the soil and precedes the onset of egg laying and is therefore well-suited to controlling the most widespread and key target pest, black vine weevil.
- Beating tray sampling is a practical method to determine when adult weevils are active in the canopy and to follow sprays to evaluate effectiveness of control. During the harvest period, the harvesting machine itself is the best tool for monitoring most insects that reside in the canopy.
- For the most part, Bifenthrin continues to provide good weevil control and it's miticidal properties are a fringe benefit.
Orange Tortrix (Skagit County)
- This leafroller is a possible harvest contaminant particularly in fresh market fields which are less likely to be sprayed with a pre-harvest insecticide.
- Monitor first generation summer caterpillars by examining 5 primocane shoot tips/ hill from 20 hills per site. Do this at 4-5 sites per field. If even one of the 5 shoot tips is infested, the hill is recorded as infested. Action threshold for Bt spray is 10% infestation of hills (2/20 hills per site).
- Sample two to three times during June
Fruit and Cane Botrytis
- With the recent documentation of fungicide resistance (1998), and research confirming the effectiveness of some new materials (Switch, Elevate), focus is now on clearly understanding and implementing strategies for rotation of effective materials to manage resistance.
- Typical program is 3 to 5 sprays beginning in early bloom and up to harvest. Reduced frequency of spraying can be accomplished by extending the spray interval to 1014 days when weather allows.
Phytophthora Root Rot,Phytophthora fragayiae
- Symptoms associated with root rot including wilting primocanes, scorched leaf margins, and premature collapse of fruiting canes are pronounced during the harvest period. Take note of areas within a field that exhibit these symptoms.
- Sampling crown and root tissue from these areas for laboratory analysis can be useful in determining the need for and delineation of treatment area.
Post Harvest (Mid -August through September)
The two most common species are the Twospotted, Tetranychus urticae and the Yellow spider mite, Eotetranychus carpini borealis
- Both can increase rapidly during and after harvest partially depending on densities of the naturally occurring predatory mite, Neoseiulus fallacis
- Sample by collecting 30 primocane leaflets per site from 3-5 sites per field. Count the number of spider mites and predator mites if numbers aren't too high (>25 spider mites/leaf)
- Ratio of I predatory mite to 10 spider mites is favorable for biological control.
- Also consider degree of damage to leaves and extent of injury to the plant
- Action thresholds are 25 twospotted or 75 yellow mites per leaflet prior to early September.
- No clear correlation between insecticide use and spider mite flare-ups documented in raspberries in Whatcom County.
- Apply fungicide to base of primocanes immediately after harvest if field is infected with cane blight.
- Delay tying primocanes to the wire until leaf drop in yellow rust-infected fields.
- Sample soil and roots for plant parasitic nematodes comparing good vs. poor areas.
- Help evaluate your fungicide program by examining lower portions of primocanes in September for incidence of spur blight lesions. (1 lesion per 2-3 canes is low incidence, 3-4 lesions per cane is high level of infection)