WSU Whatcom County Extension

Integrated Pest Management for Raspberries

Dormant/Pre-Bloom

Biology and Monitoring

(March through Late May)

Insects
Diseases
Vertebrates

     • Climbing Cutworms
     • Obliquebanded Leafroller
     • Orange Tortrix Leafroller
     • Raspberry Beetle (Fruitworm)
     • Raspberry Crown Borer
     • Spider Mites
     • Strawberry Crown Moth
     • Weevil
 

     • Cane Blight
     • Spur Blight
     • Phytophthora Root Rot
     • Yellow Rust

     • Voles

 

Biology

Insects

Climbing Cutworms

Large caterpillars may be present as buds begin to swell and break. They are active at night, feeding on primary buds and new growth. Infestations are usually spotty within a field. Early season cutworms are rarely a problem, but if present, they can reduce yield measurably.

 

Obliquebanded Leafroller (OBLR)

The larval stage of this insect is the dominant stage found during April and May. OBLR overwinters in the larval stage, often in leaves trapped between canes. As new leaves are formed in the spring, these insects crawl onto the new foliage where they feed on and roll leaves. The feeding does not usually cause significant damage to the plant but the second generation of leafroller caterpillars can be a harvest contaminant in July and August. OBLR moth flight may start in late May, but peak moth activity and highest pheromone trap counts are usually not seen until late June and early July.

 

Orange Tortrix Leafroller (OT)

The larvae of this insect overwinter on canes, dried leaves and become active in spring with the onset of new growth. Rolled leaves webbed together form a protective nest indicating the presence of leafroller larvae. OT is considered a major harvest containment; however, webbing and feeding is rarely an economic issue. Adult moths emerge in late April to May and lay eggs for the next generation. There are three or four overlapping generations per year. This pest is not found in Whatcom County.

 

Raspberry Beetle (Fruitworm)

Overwintering raspberry beetles emerge from the soil during April and May. This small (1/6-inch long) brown beetle feeds on fruit buds and unfolding leaves during the early season. The beating tray is a useful tool for monitoring adult beetle activity prior to and during bloom. White sticky traps, such as the Rebell® Bianco, can be effective for monitoring flight activity. The best time to control this insect when it is numerous is prior to bloom and before it begins laying eggs.

 

Raspberry Crown Borer

This insect requires two years to complete its life cycle. First year larvae, white and ¼ inch long, overwinter in cells just below the bark at the base of canes. They begin to feed in early March on cane buds around the plant crown and will bore into the canes during the spring. Burrowing continues through the first summer. The 2nd winter is spent in the roots and crowns. Burrowing continues the 2nd summer in the roots and crown. By midsummer, these 2nd year larvae undergo 2 to 3 weeks of pupation in the crown before emerging as an adult moth. Their feeding causes cane swelling at or below the soil surface. Infested canes become spindly and canes often break off at ground level during winter tying. Damaged canes often have uneven bud break or young laterals, which collapse. Tunneling damage can reduce cane vigor and yield. Evidence of crown borer damage cannot be ignored as the pest population can increase rapidly.

 

Spider Mites

Yellow mites emerge earlier than two-spotted spider mites and can be found in primocane foliage along the top trellis wire from April to May. Overwintering females are bright yellow and contain no food spots. Two-spotted spider mites begin emerging in April, but are more commonly found on older or mid-shoot floricane leaves before moving into the upper canopy latter in the season. Two-spotted overwintering females are orange-colored and as they feed will begin to take on the species’ normal yellow green hue with two dark-colored food spots.

 

Strawberry Crown Moth

This insect occurs wherever strawberries are grown, but has been found within raspberry fields in the Willamette Valley and Southwest Washington. The Strawberry Crown Moth (SCM) overwinters in the crown as a dormant larva in a silken cocoon. They become active in April and May and feed for a short time before pupating in the crowns in May and June. Adults emerge in Late June and July, mate, and lay eggs on dead leaves or green leaves around the base of the plant. Unlike in strawberries, larvae in caneberries can be controlled because the pest is exposed on the surface of the root and crown during feeding and development. Chemical treatments should be made in spring or fall, which correspond with chemical drench used to control the raspberry crown borer.

 

Weevil

At this time of the season, most black vine weevils are in the larval or pupal stage. They are most commonly found in the plant row within the top 6" of soil. The white larvae feed on raspberry roots until they pupate and finally emerge as adult weevils usually beginning in mid-May.

Clay colored weevils are slightly smaller than black vine weevils and begin emerging very early in the season as buds break and new leaves are just forming. For this reason, it is also called the "bud weevil". This weevil is not widespread, but in some years and in some fields, it can cause significant damage to developing shoots and therefore it can impact yield.

 

Diseases

Cane Blight

Infected tissue appears as reddish lesion up the cane from a wound site. The best timing for fungicide applications is immediately after harvest, but inspection during the dormant and pre-bloom period confirms presence of the disease.

 

Spur Blight

This common cane disease appears as cracked gray areas on canes around buds. Tiny black pimples form in affected areas. This disease is initially managed by a delayed dormant lime-sulfur application, followed by 2 to 3 early summer (mid-May to early-June) fungicide applications.

 

Phytophthora Root Rot

When present, this microscopic fungus is able to survive in the soil for several years. When soil temperature and moisture are favorable, it produces a swimming stage called a zoospore which enables it to infect healthy plant roots. In fields which are infected with this fungus, optimum discharge of zoospores occurs when soils become completely saturated with water. Some fields are free of this disease, and therefore soil-applied fungicides should not be used as a preventative unless symptoms are present and the disease-causing organism has been identified through laboratory analysis of root and crown tissue. Age of the planting and the size of the affected area should also be considered to guide treatment decisions. Prior to planting new fields, be sure to sort through plants and discard any plants with poor root systems.

 

Yellow Rust

This disease first appears as yellow pustules (aecia) on upper and lower leaf surfaces near the wire. This initial stage of infection is not usually visible until mid- to late- April. These aecia produce spores called aeciaspores, which subsequently give rise to secondary foliar infections called uridia. It is the uridia stage which repeatedly produces spores during the summer and is very difficult to control with fungicides. Late in the season, the uridia produce spores which allow the fungus to overwinter and reinfect foliage the following spring. These overwintering spores are called teliospores. Management of yellow rust focuses on:
• Delayed dormant lime sulfur to reduce viability of teliospores,
• Protectant fungicide application(s) to stop infection from aeciaspores, and
• Delaying cane tying until after leaves have dropped in the fall.

 

Vertebrates

Voles

Voles resemble house mice; they are 6-9 inches long, and gray or brown in color. They create tunnels in the soil and feed on plant roots and foliage near the ground. Their gnawing and chewing can girdle roots, crowns, canes and may lead to cane loss. Their tunneling creates air pockets in the root zone, which may further impact plant development.

 

Monitoring

(March) (April through mid-May)

Follow general guidelines in the “Introduction” section. For each pest below, record pest numbers or symptoms on record sheet.

March

Insects

Climbing Cutworm

  • Examine buds and new growth in several areas within each field for signs of cutworm feeding in late March and early April. Inspect 5 buds and new shoots per hill. Record number of buds/shoots damaged by cutworms.
  • Where damage is found, search base of plant during day to identify the pest.

 

Orange Tortrix Leafroller (OT)

Pheromone Traps
  • In Western Oregon and Washington areas south of Whatcom County, pheromone traps should be placed in fields and checked weekly to monitor adult male activity. Numbers may be low during this time of the year, but it is advised to begin checking in order to monitor the occurrence of peak flight.
  • Hang one to two traps (depending on field size) from the top trellis within the canopy.
  • Check traps weekly by removing, counting, and recording the number of OT moths.
  • Replace lure as suggested by the manufacturer (usually at four week intervals) and trap bottom when debris limits the usefulness of the trap.

 

Raspberry Crown Borer

  • Monitoring this pest is difficult because it is hidden away in the crowns and canes of the plant.
  • Pay particular attention to weak areas in the field which have smaller, spindly canes or canes that break at the base when tying up to the wire in the winter and spring.
  • Look for hills with low cane numbers. Record locations where RCB is found and % of hills infested.

 

Strawberry Crown Moth

  • The pest will be hidden away in the crown of the plant and therefore will be difficult to scout for.
  • Watch for weakened areas within the field containing brittle or collapsed canes. This may be an indication of the presence of larvae within the cane. Signs of feeding on the outer crown and root surface may be present.
  • Examine the crown and lower canes for signs of boring.

 

Weevil

  • Check soil around base of plants at several sites in a field for weevil larvae. Record areas where larvae are found.
  • Examine 5 buds and new laterals per hill for signs of damage from the clay colored weevil. Record number of buds/shoots damaged by weevils.
  • Plan on summer treatments if weevils are commonly found.

 

Diseases

Cane Disease

  • Examine canes for spur blight which appears as cracked, gray areas on canes around buds. Tiny black pimples form in affected areas. Record % of hills infected.
  • Examine canes at catcher plate height for cane blight (less common) by scraping bark away to see vascular tissue. Record % of hills infected.

 

Phytophthora Root Rot

  • Note any low areas which remain wet, particularly after winters of heavy rainfall.
  • Return to these areas in June with onset of hot weather to evaluate Phytophthora symptoms.

 

Vertebrates

Voles

  • Spring monitoring is done to assess winter mortality and new populations.
  • Dead plants can be located during the dormant period by giving them a tug. If they move very much, the entire root system is probably gone. In the growing season, damaged plants are leggy and thinly leafed with a reddish tinge to the foliage. Removing the plant from the soil may reveal a root system that looks like it was run through a pencil sharpener.
  • Look for tunnel entrance holes about one inch in diameter, surface runways through grass, droppings and\or chewing marks on canes and roots.
  • Monitoring stations can be constructed using a protected shelter to cover a runway or tunnel entrance. Shelters can be constructed using roofing shingles or PVC piping. Place an apple wedge as bait underneath the shelter. Check the apple bait every 24 hours for 2-3 days. Inspect the apple wedge for feeding damage. Four to eight bait stations per acre can provide an accurate assessment of vole populations. Record % of stations positive for feeding damage.
  • Treatment Threshold - management is needed when 40% of the bait stations show positive feeding damage after 24 hours. Monitor again 2-3 weeks following treatment to determine efficacy.

April through mid-May

Insects

Climbing Cutworms

  • Examine buds and new growth in several areas within each field for signs of cutworm feeding in late March and early April. Inspect 5 buds and new shoots per hill. Record number of buds/shoots damaged by cutworms.
  • Where damage is found, search base of plant during day to identify the pest.
  • Concentrate monitoring in areas where there is noticeably less shoot growth which may be due to cutworms.

 

Obliquebanded Leafroller (OBLR)

Monitoring Larvae
  • Select 20 hills/plants at each site and examine shoot tips for presence of caterpillars.
  • Examine a maximum of 5 shoot tips/hill to determine if the hill is infested.
  • Once an infested shoot tip is found, do not examine any more shoot tips at that hill, and record that hill as infested. If you examine five shoot tips without finding any caterpillars, record that hill as clean.
  • Record the number of infested hills for each site that you sample.
  • Add up the total number of infested hills that were detected and divide by the total number of hills that you examined. Multiply this number by 100 and you have the percentage of leafroller-infested hills.
  • If 10% or more hills are infested, then a spray may be advisable to control the overwintering spring generation prior to bloom.
  • Sample fields for larvae at least every two weeks in April and May. This insect can also be detected using the beating tray sampling method but action levels based on this monitoring tool have not been established.
Pheromone Traps
  • Place OBLR pheromone traps out in the field in mid-May. Trap catch can be used to determine the timing of infestation from second generation caterpillars, which can be a harvest contaminant during July and early-August.
  • Place one or two traps in each field, approximately ten feet from the windward edge of the field.
  • Hang them from the top trellis wire near canopy height.
  • Check traps regularly by removing, counting, and recording the number of OBLR moths.
  • Replace pheromone lure as suggested by manufacturer (usually at four week intervals).

 

Orange Tortrix Leafroller (OT)

Monitoring Larvae
  • Larvae will begin feeding on developing leaves in late March and April and complete development in late May. Pupation occurs in webbed leaves in the canopy and in leaf matter on the ground.
  • Use methods described for OBLR to scout for larval presence.
  • If 10% or more hills are infested, then a spray may be advisable to control this overwintering spring generation prior to bloom.
  • Sample fields for larvae at least every two weeks. This insect can also be detected using the beating tray sampling method but action levels based on this monitoring tool have not been established.
Pheromone Traps
  • Pheromone traps should be placed in fields and checked weekly to monitor adult male activity.
  • Hang one to two traps (depending on field size) from the top trellis within the canopy.
  • Check traps weekly by removing, counting, and recording the number of OT moths.
  • Replace lures as suggested by the manufacturer and trap bottom when debris limits the usefulness of the trap.

 

Raspberry Beetle (Fruitworm)

  • Monitor by taking ten beating tray samples from each of four - five sites distributed across a field.
  • Record the number of adults detected at each site.
  • Counts of 1-2 beetles per 10 trays have been recorded in late April and early May with no reported damage to fruit.
  • Examine fruit buds for signs of adult feeding and pay attention to feeding damage to leaves, which appear as slits between the veins on unfolding leaves.
  • Consider treating adult beetles prior to bloom if they are detected at most sites.
  • Monitor adult flight activity with white sticky traps, such as the Rebell Bianco. Locate traps along field edges near adjacent raspberry fields or areas of alternate Rubus hosts (e.g. blackberry, thimbleberry). Check traps weekly to assist decision-making.
  • Trap thresholds depend on processing type; an average of 2 per trap for IQF and 5/trap for other processing types is a good starting threshold.

 

Raspberry Crown Borer

  • Crown borers are in the caterpillar stage at this time of the season, feeding on and within lower canes and crown tissue. Their feeding causes swelling or galls at or below the soil surface.
  • Examine canes and crown tissue in areas of a field which show symptoms associated with damage from crown borer.

 

Spider Mites

  • Start sampling for spider mites in early May.
  • White speckling on the leaves is a sign of mite feeding.
  • Examine leaves using a 10X hand lens for presence of mites and mite predators.
  • Collect ten leaflets per site from a minimum of four sites distributed throughout a field.
  • Count the number of spider mites and mite predators and record information at each site.
  • Make note of the predominant mite stage (recent hatch, mixed, or mostly adult).
  • Estimate spider mite egg density by observing the ratio of eggs to spider mites on a leaf or two.
  • Mite samples should be taken at least every two weeks during May and June.
  • The following should be recorded:
         - Two-spotted mites
         - Yellow mites
         - Beneficial insects
  • Stethorus is the most effective mite predator in raspberries, but is also very sensitive to pyrethroid insecticides. Stethorus is easiest to find in the early spring when the small black adults can be seen on the underside of leaves.

 

Strawberry Crown Moth

  • This pest is active during this time and is feeding inside the crown before beginning pupation, but is still difficult to scout for.
  • Watch for weakened areas within the field containing brittle or collapsed canes.
  • Examine the crown and lower canes for signs of boring.

 

Weevil

  • Inspect 5 buds or shoots per plant and record # of buds or shoots with damage.
  • Look for leaf flagging, bud damage, and notching of leaves.
  • Check soil around the base of plants for weevil larvae to determine life stage present.
  • If you suspect this insect is present at damaging levels, sample at night using a beating tray to confirm. (Use of the beating tray is described in detail in the Bloom and Pre-Harvest section.)
  • Consider summer treatment with detection of 1 weevil per 10 beating tray samples or if weevil larvae are commonly found.

 

Diseases

Yellow Rust

  • Starting in late April, examine the oldest leaves on developing laterals near the wire for infection. This procedure can be integrated into mite counting which usually begins in late April or early May.
  • Watch closely to determine when these pustules begin to sporulate. Fungicides can be applied to protect new foliage as sporulation begins.
  • Record disease severity on a scale of 0-3.

 

Vertebrates

Voles

  • Look for tunnel entrance holes about one inch in diameter, surface runways through grass, droppings and/or chewing marks on canes and roots.
  • Monitor for voles using monitoring stations with apple baits, and record percent of stations positive for feeding damage.
  • Treatment Threshold - management is needed when 40% of the bait stations show positive feeding damage after 24 hours. Monitor again 2-3 weeks following treatment to determine efficacy.

 

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WSU Whatcom County Extension • 1000 N. Forest St., Suite 201, Bellingham, WA 98225 • (360) 778-5800 • whatcom@wsu.edu