Bloom
Biology and Monitoring
Insects |
Diseases |
Vertebrates |
• Black Vine Weevil • Orange Tortrix Leafroller • Raspberry Crown Borer • Strawberry Crown Moth |
• Blackberry Rust * • Cane & Fruit Rot Botrytis | • Voles |
*More commonly found on ‘Evergreen’ cultivar.
Biology
Insects
Black Vine Weevil
Black vine weevils begin emerging from the soil mid to late May and increase through the end of June. When weevils first emerge, their bodies have not fully hardened and are quite soft. Adult weevils begin laying eggs approximately one month after emergence. Egg laying continues throughout the summer months. Eggs hatch within 2 to 3 weeks and larvae burrow into the soil to feed on roots and crowns.
Orange Tortrix Leafroller (OT)
Adults begin emerging late April to May and lay eggs in flat masses on canes and on the lower surface of leaves. This generation lays eggs for the next generation which will potentially coincide with harvest and therefore contaminate fruit. Due to overlapping generations and successive egg hatches it is common to find eggs, larvae, pupae, and adults at the same time.
Raspberry Crown Borer
By mid-May most of the first year larvae have bored into canes and started working their way into the crown of the plant to feed. Second year larvae, which have been feeding in the roots and crown become full grown in late June to July. Larvae are white with brown heads and have six short legs. First year larvae are about ¼ inch long. Second year mature larvae range from 1 to 1 ½ inches long.
Strawberry Crown Moth
Larvae are still actively feeding in May before pupating in the crowns in late May and June. Mature larvae are about ¾ inch long, white with a dark brown head. Adults begin emerging in late June, mate, and lay eggs on leaves around the base of the plant. Adults are clear winged moths that resemble yellow jackets, with a wingspan of about ¾ inch. Forewings are nearly opaque with the edges dark bronze to almost black. Hindwings are transparent with dark veins and dark fringe. The abdomen is black, and banded with yellow on the second, fifth, and sixth segments.
Diseases
Blackberry Rust
Aecia and uredinia reproductive spore types can be found during this time of year. Infected leaves show purple leaf spots on the surface with corresponding yellow pustules on the underside. When the yellow pustules (uredinia) sporulate, they can infect flower buds, leaves, and stems of primocanes and floricanes. New uredinia are produced from these infections and continue the epidemic, building up disease in rapid, successive cycles. Severely infected leaves may turn brown, shrivel and fall from the canes.
Cane & Fruit Rot Botrytis
Disease develops when conditions are warm and moist or when temperatures are cool and the foliage remains wet for a long period. The spores can infect mature leaves, resulting in primocane infections through petioles. Infected new canes wilt, die and may be covered with grey mold. During bloom, the fungus colonizes healthy or senescing flower parts and establishes within the receptacle of the young fruit as a latent infection. Infected flowers turn brown and shrivel when dry conditions exist. Under moist conditions, grey tufts of fungus can be seen on blighted blossoms. Fruit infections usually appear as soft, light brown, rapidly enlarging areas on the fruit.
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
Follow general guidelines in the “Introduction” section. For each pest below, record pest numbers or symptoms on record sheet.
Insects
Black Vine Weevil
- Adult weevils can be detected by placing a beating tray under the foliage and shaking the plant gently. A sheet can be used if a beating tray is not available by placing it on the ground and shaking the canopy above.
- Take 10 beating tray samples per site and record the number of weevils found for each inspection.
- Treatment Threshold - Typically 1-2 weevils\10 tray samples indicates a pre-harvest spray. Harvest contaminant thresholds will vary according to end product usage and processor. Scout field soon after treatment to verify effectiveness.
Orange Tortrix Leafroller (OT)
Adults
- Monitor pheromone traps to determine peak flight in order to predict the onset of a second generation which may be a harvest contaminant.
- Regularly remove, count and record the number of OT moths in traps.
Larvae
- Select 20 hills 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 the hill as infested. If you examine five shoot tips without finding any caterpillars, record the hill as clean.
- Record the percentage of leafroller-infested hills for each site you sample.
- Treatment Threshold - Chemical treatment may be necessary if 10% or more hills are infested, although check with buyer for their recommended threshold.
- Effective treatment relies heavily on timing applications to newly hatched, small larvae and good coverage.
Raspberry Crown Borer
- Monitoring for this pest is especially difficult this time of the year because both first and second year larvae are hidden within the roots or crown of the plant.
- Scout each site for wilting or dying canes and inspect plant for signs of boring (holes with sawdust-like frass). Feeding may also cause swelling or galls to form at or below the soil.
- Remove collapsed and dead canes from the soil and inspect crown and root structure for signs of larvae feeding.
- Record percent infested hills.
- Treatment Threshold - If more than 5% of the plants have damage, chemical controls are recommended.
- Insecticide application must be carefully timed, thorough and followed with irrigation or preceding rain.
Strawberry Crown Moth
- Watch for weakened areas in the field containing brittle or collapsed canes.
- Examine the crown and lower canes for signs of boring and record percent infested hills.
- Hang one to two pheromone traps in the field (depending on field size) on the lower wire of the trellis, as SCM are low fliers.
Diseases
Blackberry Rust
- Conduct a visual search at each site for blackberry rust symptoms and record level of damage on a scale of 0-3.
- Scout field regularly for new infections occurring as purplish spots on the upper leaf surface, as well as their corresponding yellowish-orange pustules on the lower leaf surface.
Cane & Fruit Rot Botrytis
- Inspect leaves, canes and blossoms during wet conditions and/or in fields containing heavy foliage for disease development.
- Record level of cane and blossom botrytis symptoms on a scale of 0-3.
- Infected new canes wilt, die and may be covered with grey mold.
- Infected flowers turn brown and shrivel when dry conditions exist. Under moist conditions, grey tufts of fungus can be seen on blighted blossoms.
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, as described in the profile page.
- 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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