Iowa Strawberry Growers Learn How and Why to Foliar Sample

Agriculture and Natural Resources Extension
Iowa State University

Extension Lead(s)
(name, position, counties served, contact information)

Joseph M Hannan
Commercial Horticulture Field Specialist
Serving Central and Western IA
28059 Fairground Rd.
Adel, IA

Your Position


POW # and Team

 ­­­­­_____100 Corn and Soybean Production and Protection
­­­­­_____ 110 Dairy
­­­­­_____ 120 Farm and Business Management
­­­­­__X__ 130 Horticulture: Commercial and Consumer
­­­­­_____ 140 Iowa Beef Center
­­­­­_____ 150 Iowa Pork Industry Center
­­­­­_____ 160 Natural Resources and Stewardship
_____170 Pesticide Applicator Training
_____180 Other ANR Programs

ANR Priority (select all that apply)

­­­­­_____Global Food Security and Hunger
­­­­­__X__Regional Food Systems
­­­­­__X__Natural Resources & Environmental Stewardship
­­­­­_____Food Safety
­­­­­_____Sustainable Energy – Biofuels & Biobased Products
­­­­­_____Climate Change

Title of Success Story

Iowa Strawberry Growers Learn How and Why to Foliar Sample

Continuing Story

__X___ No                _____  Yes (If continuing, what story?)

Knowledge Areas: (USDA categories)


Desired Changes

  • Participants in the program learned the importance of collecting foliar samples for determining nutritional status of their fields.  They also learned how to correctly collect foliar samples.
  • Participants in this program will use foliar samples to make better decisions to more accurately fertilize their fields to increase strawberry yield and quality.
  • Participants will encourage other fruit growers to start collecting foliar samples and teach them how to collect samples.

(Why is it important to address this issue with education?  What are the desired changes?)

Analysis of soil samples is a poor indicator of actual plant nutrient status because they do not measure actual nutritional status of plants.  A better method to determine plant nutrient status is through foliar sampling.  Foliar samples measure the nutritional status of a plant and directly correlate to plant nutritional requirements.  However, very few fruit and vegetable growers are using this tool in Iowa.  Knowing accurate plant nutritional status helps growers maximize profit, increase overall fruit quality, and reduces the potential for nutrient leaching or runoff in the environment.  A project was developed to teach strawberry growers how and why to foliar sample and to provide them the knowledge they need to promote the practice among other growers.

(Outputs: activities, numbers reached, publications, products)

An article was published in the e-newsletter and website describing how and why to collect foliar samples.  Together, the newsletter and website reached more than one hundred Iowa growers.  Five strawberry growers across the state of Iowa invited me to their farm to teach them how and when to collect foliar samples and to discuss why they currently are not collecting foliar samples.  Foliar samples were collected from each of these farms for analysis and a fertility report was given to each participant based upon their most recent soil and current foliar samples.  Each report included a detailed description of how the foliar samples were better than soil analysis alone.  A full report of the economic benefits of foliar sampling was published in the newsletter and website.  Fertility guidelines for Iowa grown strawberries were updated to the most recent research and posted on

RESULTS (Outcomes:  specific changes that occurred in Learning, Actions, Conditions; how outcomes were measured)

Each participant learned how to collect foliar samples by actively participating in the sample collection process and why they should collect foliar samples. 

Through verbal discussion with growers:
80% used the foliar samples to adjust their fertility program in 2011.
60% indicated that they will collect foliar samples in 2012.
60% indicated that they will promote foliar sampling to other growers.

Through discussions with growers, we learned what the barriers are that are preventing growers from collecting foliar samples and discussed solutions to those barriers that will be trialed in 2012.

Finally, not all growers are large enough to justify the cost of foliar sampling.  However, because the results were collected as a group across the state, we were able to see trends in plant nutritional status that allowed us to make generalizations across the state.

Public Value (now or future)
(Impact:  Who benefits beyond participants and how?  What conditions changed?)

The goal of this ongoing project is to reduce the risk of fertilizer runoff and leaching and increase the production quantity and quality of locally grown strawberries.  Foliar samples at multiple sites indicated excessive nitrogen was applied and that the rate of nitrogen application could be reduced by 15% at those locations, thus reducing the total potential nitrogen that could leach or runoff.  In addition, maximum quality was not being met as zinc and/or boron deficiencies were observed at 80% of the sites.

Major Partners or Collaborators

ISU Extension and Outreach and Iowa Strawberry Growers

Where story took place
(Region, campus, multi-regional)


Fiscal Year


Multi-state or Integrated (Ext + Research)


Funding Source

ISU Extension and Outreach = 50%
Iowa Strawberry Growers = 50%


Strawberry nutrition, commercial fruit and vegetable production, local foods


Page last updated: December 22, 2011
Page maintained by Julie Honeick,