1. Strawberry Integrated Pest Management with the
University of Maine Cooperative Extension.
David T. Handley* and James F. Dill, University of Maine Cooperative Extension
Cooperative
and Maine Agricultural and Forestry Experiment Station
Highmoor Farm P.O. Box 179, Monmouth, ME 04259 david.handley@maine.edu
Abstract How it works:
The University of Maine Cooperative Extension Strawberry IPM program was initiated in 1993 to help •Scout the field weekly, starting when flower buds are visible
farmers better manage the challenging pest complex that threatens this high-value crop. Additionally, we •Sample enough plants to reflect the situation in the entire field
wanted to make strawberry pest management practices more “consumer-friendly” because the crop is
nearly always sold fresh to customers at farm stands or as “pick-your own”. Frequent, preventative •Use specific action thresholds to determine if controls are necessary for any pest
pesticide sprays were the typical method employed to control the most common problems threatening •Use alternative management techniques to prevent action threshold from being reached
strawberries, including tarnished plant bug (Lygus lineolaris), strawberry bud weevil (Anthonomus
signatus), two spotted spider mites (Tetranychus urticae) and gray mold (Botrytis cineria). Through a Strawberry Bud Weevil or Clipper (Anthonomus signatus)
series of Extension presentations, newsletters and grower visits, the Integrated Pest Management (IPM)
program introduced pest monitoring techniques for strawberries, including weekly field scouting, and
specific action thresholds for each pest to determine when and if to spray. Eight to ten farmer volunteer
sites are monitored by Extension IPM scouts each growing season and the pest situation and
recommendations for those fields are delivered to over 65 growers statewide through weekly newsletter,
e-mail, and blog updates. Additionally, we have worked with growers to adopt alternative strategies such
as pest resistant cultivars, biological controls and insect barriers. Recent program evaluations by
growers indicate that nearly all participants have reduced pesticide applications (83%) and costs (100%)
as a result of the program. Additionally, growers now time sprays in response to pest monitoring results,
and most have adopted at least one non-chemical alternative pest management strategy.
Damage: Clippers lay eggs in flower buds and clip them off.
Monitoring: Starting at flower bud emergence, check all flower buds in 0.5m row length samples at 10
locations. Look for freshly clipped buds or the presence of clippers.
Action Threshold:1.2 clipped buds per 0.5m of row or one live adult. Border sprays may be effective:
Tarnished Plant Bug (Lygus lineolaris)
The Maine Situation:
•Strawberries are a high value crop, sold fresh to local consumers.
•Insect and disease pests can ruin crop quality and yield
•Consumers prefer minimal pesticide use.
The Questions:
•Can Integrated Pest Management (IPM) reduce pesticide use while maintaining crop quality?
Damage: Adults and nymphs feed on flowers and immature fruit, causing seedy berries.
•Will farmers and consumers accept IPM practices in strawberries? Monitoring: Starting at early bloom, tap 3 strawberry flower clusters per site over a white plate. Look for
nymphs that have fallen from the flowers. Sample 10 sites per field or 30 flower clusters total. Sample
The Program: early bloom through petal fall.
Action Threshold: 4 clusters with nymphs out of 30 samples or an average of 0.25 nymphs per cluster.
•Offer annual training in strawberry IPM techniques to farmers
•Winter training sessions, spring twilight meetings/demonstrations
Two-spotted Spider Mites (Tetranychus urticae)
•Monitor (“scout”) important pest populations weekly on volunteer farms (9-12 participate/year)
•Publish weekly pest situation and recommendations in newsletter, blog and webpage
•120 subscribers, 400+ website visits/year
Photo: MSU
Maine Impacts (from grower surveys):
•Significant reductions in pesticide use (up to 50%)
•Reduced production costs (up to $100/acre)
•Improved crop quality Photo: MSU
•Improved customer satisfaction Damage: Feeding on foliage causes discoloration and poor vigor.
•Increased crop profitability Monitoring: Pick 60 leaves from throughout the field. Examine leaf undersides for the presence of mites.
Action Threshold: 15 leaves with mites per 60 leaf sample or 25%. Encourage natural predators.
Improvement through research:
•Testing strawberry varieties for plant bug resistance Gray Mold (Botrytis cineria)
•Surveying impacts of strawberry bud weevil injury
•Testing low risk pesticide efficacy and bio-controls
Damage: Fruit rot as fungus grows through ripening berries
Monitoring: Follow online model for moisture and temperature conditions related to spore release
Action Threshold: Apply fungicides at 10% bloom and full bloom. Repeat only if conditions warrant.