Pre-Bloom
Biology and Monitoring
Insects |
Diseases |
Vertebrates |
• Black Vine Weevil • Orange Tortrix Leafroller • Raspberry Crown Borer • Strawberry Crown Moth |
• Blackberry Rust * • Cane Botrytis • Purple Blotch |
• Voles |
*More commonly found on ‘Evergreen’ cultivar.
Biology
Insects
Black Vine Weevil
During this time most black vine weevils are in larval or pupae stage. They are most commonly found within the top 6-inches of soil. The white c-shaped larvae will feed on roots until they pupate and emerge as adult weevils beginning in mid-May.
Orange Tortrix Leafroller (OT)
Overwintering larvae survive in plant debris on the ground, in surrounding weeds, or in debris pinned between canes. Larvae will begin feeding on developing leaves in late March and April and complete development in late May. As they feed, they roll and tie together individual or clustered leaves at the shoot tip with webbing. The rolled leaves form a protective nest indicating the presence of leafroller larvae. Adult moths emerge in late April to May and lay eggs for the next generation. There are three or four overlapping generations per year.
Raspberry Crown Borer
The Raspberry Crown Borer (RCB) takes two years to complete its life cycle. They overwinter the first year as tiny larvae at the crown of the plant within blister-like cells or protected areas under the bark. Larvae become active in the spring and begin feeding on cane buds. Second year larvae overwinter in the roots or in tunnels bore into the crown of the plant and begin feeding in the spring. 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 inch long.
Strawberry Crown Moth
The strawberry crown moth (SCM) is found wherever strawberries are grown and has been found in caneberry fields in the Willamette Valley of Oregon and Southwest Washington. SCM overwinters in the crown as dormant larvae in silken cocoons. They become active in April and May and feed for a short time before pupating in the crown in May and June. Mature larvae are about ¾ inch long, white, with a dark brown head.
Diseases
Blackberry Rust
Blackberry rust overwinters as black, sticky pustules (telia) on infected leaves attached to canes or trapped in cane bundles. Sporulation occurs in the spring, which infects new succulent growth of primocanes and floricanes. These primary foliar infections (aecia) occur as purplish spots (2-3 mm) with yellow to tan centers on the upper leaf surface. As the fungus progresses, yellowish-orange pustules (uredinia) develop on the lower leaf surface directly under the initial infection.
Cane Botrytis
The pathogen, Botrytis cinerea, overwinters as minute, black, fungus bodies (sclerotia) on bleached canes or as mycelium in leaves and mummified berries. Cane lesions exhibit typical concentric “watermark” patterns from fall through late winter. Spores are produced in the spring under moist humid conditions, which are dispersed by wind, rain, and overhead irrigation.
Purple Blotch
The best time to monitor for purple blotch lesions is in early spring; however symptoms will not be present until a chilling requirement is met. If conditions favor disease development (cold, wet winters), lesions turn purple with red margins and are easily spotted because the canes’ vegetative buds have not yet developed. Affected areas are 0.5 to 2 inches long.
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
- Examine the soil around the root system of plants showing signs of water stress (wilting, lack of vigor) for larvae and record the percentage of infested plants.
Orange Tortrix Leafroller (OT)
Adult
- Place pheromone traps in one to two locations (depending on field size) in the field in early March.
- Hang traps 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 one month intervals) and trap bottom when debris limits the usefulness of the trap.
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 number of infested hills for each site you sample.
- Add the total number of infested hills that were detected and divide by the total number of hills you examined. Multiply this number by 100 to obtain the percentage of leafroller-infested hills.
- Treatment Threshold - If 10% or more hills are infested, then a spray may be advisable to control this overwintering spring generation prior to bloom.
Raspberry Crown Borer
- Monitoring is difficult because the pest spends most of its life cycle hidden within the crown of the plant.
- Watch for canes that break easily from the base during tying up.
- Search around the crown of suspected plants for signs of boring (holes and sawdust-like frass) and record percent infested hills.
- Larvae feeding may also cause swelling or galls to form at or below the soil surface.
- Treatment Threshold - If more than 5% of the plants have damage, a fall chemical controls is recommended.
Strawberry Crown Moth
- During this time, the pest will be hidden in the crown of the plant and therefore 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 also be present.
- Examine the crown and the lower portion of canes for signs of boring and record the percentage of infested hills.
Diseases
Blackberry Rust
- Conduct a visual search at each site for symptoms associated with blackberry rust and record level of damage on a scale of 0 to 3.
- During dormancy, scout field for overwintering black pustules residing on leaves attached to canes or trapped in cane bundles.
- Begin looking for new infections occurring as purplish spots on the upper leaf surface as soon as buds begin to develop.
Cane Botrytis
- In early spring, inspect canes for overwintering black fungal bodies on bleached canes.
- Record level of damage on a scale of 0 to 3.
Purple Blotch
- Inspect floricanes in early spring for purple lesions with a red margin and record level of damage on a scale of 0 to 3 at each site.
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.
- 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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