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Extension > Garden > Yard and Garden > Fruit > Pest management in the home strawberry patch

Pest management for the home strawberry patch

Karl Foord, Jeff Hahn and Michelle Grabowski

Funded by NCIPM USDA

Introduction

Minnesotans who grow strawberries at home may have to combat insect pests or diseases to produce a good crop. Previous pest control strategies seeking to eliminate all pests from a garden have been shown to be unsuccessful. Today's approach combines many management methods into an integrated whole thus the name Integrated Pest Management (IPM). IPM practices have enabled growers to place an emphasis on non-chemical methods while using pesticides secondarily or as a supplement to these methods while still harvesting quality fruit. The philosophy of IPM is to seek a balance maximizing yield while reducing human and environmental risk. This follows a particular hierarchy that begins with the best practices in cultural management.

Pest identification and biology

To choose a proper management strategy, gardeners need to be able to identify pests and the damage that they cause. Gardeners can find additional help identifying common pest problems by using the online diagnostic tools What insect is this? and What's wrong with my plant? or by sending a sample to the UMN Plant Disease Diagnostic Clinic. A hand lens can be helpful in identifying insects and pathogen signs as many are less than 1/4 of an inch. Once a pest has been identified, gardeners should learn about their biology. Understanding pest biology permits one to select the timeliest and most effective management strategy.

Thresholds

Research has shown that a certain level of disease and insect pest damage can be tolerated without reducing the number and quality of fruit harvested. However, pest damage can reach levels that are unacceptable. For some pests an action threshold has been established. The threshold is typically a number of insects or percent of damage on the plant that when reached, indicates that a grower should take action to prevent unacceptable damage. Thresholds are most commonly used in managing insect pest problems and information about thresholds for specific pests are included where appropriate.

Management

The foundation of a good IPM program begins with cultural practices that reduce pest populations and minimize diseases. Consider using pesticides when cultural control practices do not reduce pest damage to an acceptable level or as a supplement to these methods.

Site selection

By choosing the right site to grow strawberries, you can lower disease and insect pest pressure. Strawberries should be planted in well-drained soil that does not accumulate standing water following a heavy rainstorm. Planting on higher ground minimizes frost damage, while increasing air circulation around the strawberry plants. Good air circulation allows the berries to dry out faster, reducing the incidence of some diseases.

Resistant cultivars

Whenever possible select strawberry cultivars that have demonstrated resistance to common diseases like Verticillium wilt. For more information about resistant cultivars, see Strawberries for the Home Garden.

Best plant care

An IPM approach assumes that good care is being taken of the strawberry plants. Consult the University of Minnesota Extension publication Strawberries for the Home Garden for horticultural information. Good cultural practices—including site selection, cultivar selection, proper planting, irrigation, renovation, and frequent harvest—all contribute to a satisfying harvest each year. These practices seek to produce the healthiest plants by avoiding situations that favor the development of diseases or contribute to insect infestations. Irrigations systems that avoid getting the leaf surfaces wet are preferred, such as drip systems or a soaker hose. If a sprinkler system is used, water plants in the mornings on a sunny day to allow leaf surfaces to dry quickly, reducing opportunities for fungal spore germination.

If possible, strawberries should be rotated to different areas of the garden every 3-4 years. Land that has been in strawberries for four years or more can build up a population of root-rotting pathogens. By moving the patch this can be avoided. Straw mulch reduces winter injury, and plants that have less winter injury have reduced disease. Straw mulch is equally important in the spring and summer as it reduces fruit and flower diseases by covering the soil and reducing spore movement carried by raindrop splash. When removing straw in spring, 1/2 to 1" of straw should be left between rows to keep fruit off the soil and reduce weeds.

Renovation

Renovation helps control diseases and insect pests by disrupting their life cycles. First, the plants are mowed and clippings removed. This helps to control diseases by removing older leaves that are infected by leaf spot or fruit rot pathogens. This helps to control insects by removing their food source and potential breeding sites. If plants are grown in rows, renovation is a good time to thin widening rows back to their original width. This will improve airflow through the patch and reduce the time that the leaf surfaces are wet, which can reduce disease severity. Regardless of the size and shape of your strawberry patch it is best to mow or cut the foliage back before August 1. A new canopy will develop by mid-August. To have a good crop in the following year requires healthy thriving plants from post-renovation to dormancy in the fall. Pay attention to the health of your plants in this time period.

Pesticides

In IPM, pesticide applications are used only when cultural controls are not effective or as a supplement to cultural controls. Before using a pesticide, be certain that you have correctly identified the pest organism and that the product you wish to apply is effective against that organism. Do not use products that are advertised as 'multi-use' or '3-in-1' to manage a single pest problem, as this would result in application of unnecessary pesticides.

If a pesticide is necessary choose one that is effective with the least ecological impact and environmental risk. Further information about pesticide application and safety can be found at http://pesticidestewardship.org and at the National Pesticide Information Center (NIPC). Information on the correct way to apply specific pesticides can be found on the product label. If pesticides are necessary, always use them exactly as directed by the product label as mandated by federal law.


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