The use of native perennial wildflowers and alfalfa trap crops to increase pollination and biological control in strawberries

The use of native perennial wildflowers and alfalfa trap crops to increase pollination and biological control in strawberries

Summary

The purpose of this project is to provide small fruit growers in the Northeast with a simple and effective management strategy for enhancing biodiversity and ecosystem services (biological control and pollination) using native perennials and alfalfa in companion plantings. We expect that planting wildflower-alfalfa strips will increase abundance and diversity of native bees resulting in greater pollination services and higher fruit yields. Similarly, we expect the wildflower-alfalfa strips to increase parasitism rates of the tarnished plant bug resulting in decreased fruit damage and higher yields. Additionally we will measure the relative benefits of using wildflowers or alfalfa alone or together to determine the role of each in enhancing ecosystem services and to explore potential synergisms

Objectives/Performance Targets

My objectives are to:
1. Quantify the influence of wildflower-alfalfa strips on pollinator community composition and pollination services in strawberry.

                  From our first year of field data we have found a significant interaction between landscape complexity surrounding the farm and the effectiveness of wildflower strips for increasing pollinator abundance. This suggests that farms in landscapes with a sufficient amount of natural habitat in the surrounding landscape do not benefit from wildflower strips. However, farms with less than 30% natural area do benefit from strips in terms of pollination services.

2. Investigate P. digoneutis biological control of tarnished plant bug to determine

       a) if parasitoids near Wildflower-Alfalfa strips achieve a higher parasitism rate and,

       b) if high parasitism correlates with reduced pest damage in the field.

                  Preliminary evidence based on fruit damage assessments suggests that tarnished plant bug damage is greater where pollination services are high and poor pollination damage is low. It is not clear if the well pollinated fruit are attracting the plant bugs, the wildflower strip itself or a combination. Parasitism rates of 2013 plant bugs will be determined in the next few weeks.

3. Disentangle the relative benefits provided by either wildflowers or alfalfa through increased pollination and/or biological control on strawberry yield.

Further analysis and data collection is needed to fully address objective 3.

Accomplishments/Milestones

To accomplish these objectives we have established 36 paired 15’x20’ plots of Jewel, a June bearing variety of strawberry on 15 farms in the finger lakes region of NY. Half of the plots had a strip (3X20’) of native perennial wildflowers (10 species, we were unable to successfully grow the late figwort and alum root) planted as plugs parallel to an end row in October 2012. These plots also had a strip (2×20’) of alfalfa planted between the wildflowers and the end row of strawberry. All other sides of the plots had grass seeded with control plots at each site receiving grass on all sides. At three of the 15 farms two additional strawberry plots were established with either wildflowers only, or alfalfa only to address objective 3.

The project is progressing as planned and establishment of plots including wildflower-alfalfa strips has been better than expected. Both the wildflower-alfalfa strips and the strawberry plots successfully survived the winter. Almost all wildflower species bloomed during their first year at each location and strawberries were harvested from 32 of the 36 plots. The remaining 4 plots experiences significant damage to the strawberry plants due to deer feeding. To prevent this issue we have established deer fencing around the effected plots. All plots have been maintained with hand weeding throughout the summer, they were fertilized with fishmeal and renovated in the fall, and mulched with straw in December.

We collected both pollinators and tarnished plant bug nymphs on several occasions at each plots in the spring and collected fruit from each plot for damage and yield assessments. Bee samples were identified and preliminary data analysis was conducted in the fall. A further season of field collections is necessary to supplement the data on pollinator diversity and meet objective 3. I plan to use the same data collection methods as in the last field season.

Impacts and Contributions/Outcomes

If successfulthis project has the potential to significantly reduce pesticide use and reliance on managed honey bees for northeastern strawberry farmers. The adoption of wildflower-alfalfa strips for ecosystem services presents not only an economic gain for farmers but can also assist in the conservation of out native beneficial insects. Our preliminary data show that the alfalfa –wildflower strips may already be having a positive impact on majority of farms where they have been deployed. I have been in regular contact with the owners and managers of the farms where my research plots are located in order to share information about the insects I collected on their farms and the early results of the project. Through these interactions I have raised awareness about the potential for biological control of tarnished plant bug and the negative impact pesticides can have on its natural enemies. I have also called attention to the diversity of insect pollination of strawberry flowers and the current decline on abundance and diversity of our native bee species. As a result of my research I have been invited to give several talks related to conservation of ecosystem services including a public talk with the Finger Lakes Land Trust, an extension talk a the New York State Agricultural Research Station’s Fruit Days and an upcoming talk at the Ithaca Native Landscape Symposium.

Collaborators: