Target Grade Level / Age Range:

Grades 6-8

Estimated Time:

45 minutes of instruction plus additional time for student research and presentations


Students will understand issues in producing Christmas trees and design solutions to things like irrigation needs, weed control, and pests and diseases.


  • Laptop, projector, and screen
  • Copies of irrigation worksheet – one per student
  • Copies of insect/disease management worksheet – one per student
  • Computers or tablets with internet access for student research and multimedia presentations

Essential Files (maps, charts, pictures, or documents)


  • Girdling – also called ring-barking, is the complete removal of the bark from around the entire circumference of either a branch or trunk of a woody plant. Girdling results in the death of the area above the girdle over time. It can be caused by animals like mice, rabbits, or deer that eat the bark and cambium layer as a food source.
  • Crown – The crown of a conifer tree is the branches, needles, and reproductive structures extending from the trunk or main stem at the top of the tree.
  • PSI – pound-force per square inch. A unit of pressure of force applied to an area of one square inch.
  • Center pivot – a method of crop irrigation in which equipment rotates around a pivot and crops are watered with sprinklers.
  • Travelers (or hose reel irrigation) – a method of crop irrigation in which a single powerful, portable sprinkler head sprays water in a circular pattern.
  • Drip irrigation – a type of micro-irrigation system that supplies water slowly to the roots of plants, either from above the soil surface or buried below the surface. Water is placed directly into the root zone to minimize evaporation. Drip irrigation systems distribute water through a network of valves, pipes, tubing, and emitters.
  • Crop scouting – process of precisely assessing pest pressure (typically insects) and crop performance to evaluate economic risk from pest infestations and disease, as well as to determine the potential effectiveness of pest and disease control interventions.
  • Integrated pest management – a multilayered approach to keeping pests and pest damage to a minimal level with the smallest cost to health, environment, and budget.
  • Cultural and mechanical control – physical methods of pest control (mowing, pruning, culling)
  • Biological control – use of living organisms (parasitoids, pathogens, predators) to control diseases, insect pests, and weeds
  • Chemical control – insecticide spray to kill insects, fungicide spray to kill fungi, etc.
  • Biorational – alternative to chemical pesticides

Background – Agricultural Connections

Most Christmas tree farms in Iowa are cut-your-own. This means that customers will come to the farm, walk out into the field, select the tree they want, cut it down, and take it home with them. Farms that look nice and can display the trees nicely will attract more customers and provide them with a better experience. Most customers will not want to walk through weedy fields to get to their tree. Weed control is also really important when trying to establish young trees that have just been planted. Grass and weeds can grow faster than the tree seedlings out-competing them for limited moisture, nutrients, light, and space. Tall grass and weeds also provide habitat for wildlife that can then girdle or cut off the young tree seedlings. Therefore, it is important to control grass and weeds to avoid these problems.

The type of weed control method used depends primarily on soil type. Less weed competition occurs on coarse, sandy soils than on rich, loamy soils. Several chemicals control grass and weeds. The Iowa Department of Natural Resources has a pamphlet on Grass and Weed Control for Tree and Shrub Seedlings that describes some appropriate chemicals. Roundup can be used as a rescue treatment, either by shielding each tree or by spraying at a reduced level in late fall. Application of chemicals must conform to the manufacturer’s recommendations. Mulching with organic mulches such as wood chips, ground corn cobs, or grass clippings also provides satisfactory weed control. Do not use manure as a mulch. Mowing between rows, combined with herbicide or mulch on the rows, will control most competing vegetation. Mowing also reduces fire hazard by diminishing fuel buildup and helps control some diseases and rodent populations.

Trees also need to be protected while they are growing. Conifer needles destroyed by fire or grazing will never regrow. Maintain fire breaks around and through the plantation to control grass fires and construct a sturdy fence to keep farm livestock out. Rodents, rabbits, and deer can damage Christmas trees. In the winter, field mice frequently girdle young stems of small trees. Rabbits usually chew on the bark. They also eat buds, which can cause serious damage. Deer feed on buds and small branches and rub their antlers on small trees, causing breakage and bark damage. Control field mice by maintaining poison-bait stations throughout the plantation or by mowing in late fall to reduce the winter habitat. Heavy hunting is a good control measure for a large rabbit or deer population. Some chemicals can be sprayed on trees to repel rabbits and deer. Insects and diseases can destroy a Christmas tree plantation. Be especially watchful in early spring and late summer for insects and any abnormal growth or appearance on the trees. If you notice any abnormal situation, consult your county extension education director or district forester.

Interest Approach – Engagement

Using the provided PowerPoint file, display slide #2 – the messy room and the clean room. Ask students if they were going to have a friend come over, which room would be more appealing to that friend to hangout? Most students should answer that the clean room would be more enjoyable and appealing. Display slide #3. Ask students if they were going to visit a farm and have to walk through the fields, which would be easier and more fun to walk through – mowed or unmowed – especially if they had to walk a long distance? Most students should answer mowed. When tree farmers invite people to their farm to select a Christmas tree, they want it to look nice and mowing can remove the weeds and help make it look nice.


  1. Display slide #4 and present the information. Ask probing questions to test students base knowledge – Why do trees need moisture to grow? Why do trees need nutrients to grow? Why do trees need light to grow? Why do trees need space to grow?
  2. OPTIONAL: If time allows, conduct the activity 1: Crops vs. Weeds Simulation from here: to reinforce the idea of how weeds compete with crops to grow.
  3. Present the information on slides 5-7 and discuss the content. Key points include 1) Tall weeds provide habitat for wildlife that can then eat or damage the seedling trees. 2) Tall weeds create a lot of biomass that can then burn in a wildfire. Tree needles destroyed by fire will never regrow and the tree can be permanently damaged. 3) Aesthetically, customers who visit tree farms like to see a well-manicured landscape that is weed-free. 4) Customers who visit tree farms need to walk through the farm easily and unencumbered to find their preferred tree.
  4. Now that students understand a little more about weed management of Christmas trees, introduce them to two more issues that farmers face – irrigation of trees and insect/disease management.
    1. As a class, watch the video on pest scouting also found on slide 9.
    2. OPTIONAL: If time allows, conduct the activity Speed Scouting for Soybean Aphids activity from here: to reinforce the idea of how insects and diseases can be identified in a growing crop.
    3. As a class, watch the video on irrigation also found on slide 10.
  5. Divide the class into two or more groups. Each group will be assigned either irrigation or insect/disease management in Christmas trees. As a group, direct them to conduct research on their topic. Provide them the worksheet with questions to answer. Use the teacher guide/key to help direct and guide student research.
  6. Once they finish their research and answer the questions, students should work together to develop a multimedia presentation to present their proposed solution to the issue. Class time can be provided or students can work outside of class time to complete this assignment.
  7. Each group should present their solution using their multimedia presentation. Each member of the student team should be involved in the final presentation.

Did you know? (Ag facts)

  • Each year in the U.S., more than 35 million Christmas trees are harvested. This tradition, dating back to the 16th century in Strasbourg, Germany (now part of France) has continued and thrived into the 21st century.
  • The first retail offering of the Christmas tree was in New York City in 1851. Each year, since 1966, the National Christmas Tree Association provides the first family with a fresh, renewable tree.  
  • Christmas trees are renewable, because every spring growers plant more than 56 million new seedlings.
  • Iowa has approximately 200 growers, producing trees both for retail lots and choose and cut operations.

Extension Activities

Suggested Companion Resources



Will Fett

Organization Affiliation

Iowa Agriculture Literacy Foundation

Agriculture Literacy Outcomes

  • T1.6-8.a. Compare and contrast the advantages and disadvantages involved when converting natural ecosystems to agricultural ecosystems.
  • T2.6-8.c. Identify farm practices for plant protection (e.g., using a pesticide, integrated pest management, cultural practices) and the harvest of safe products for consumers.
  • T4.6-8.i. Provide examples of science and technology used in agricultural systems (e.g., GPS, artificial insemination, biotechnology, soil testing, ethanol production, etc.); explain how they meet our basic needs; and detail their social, economic, and environmental impacts.

Iowa Core Standards

  • Science
    1. MS-ETS1-1. Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.