Invasive Plants in the McDowell Sonoran Preserve

• As development pushes into the Sonoran Desert, an unintended consequence has been the introduction and spread of invasive plants into natural open spaces.
• Invasive plants threaten the McDowell Sonoran Preserve by increasing the severity and spread of wildfire, displacing native plant species, and reducing biodiversity.
• Invasive plants are less desirable than native plants for wildlife forage, and in some instances, cause direct harm to wildlife.
• The natural incidence of fire in the Sonoran Desert is very low, and much more common from human-made ignitions. The Sonoran Desert ecosystem is not fire adapted and may take many decades to return to its natural state post-fire. It is also not a fire reliant ecosystem, meaning it does not need fire for regeneration.
• When wildfire does occur, Invasive plants are prolific colonizers of the recently disturbed landscape, outcompeting native plants and creating an increased risk of repeated fires.

For details on local invasives, visit the South and Central AZ Invasive Species page from SWVMA.

Non-native species with high impact in the Preserve include:

• Fountain Grass
• Buffelgrass
• Stinknet
• Sahara Mustard
• Red Brome
• Russian Thistle (Tumbleweed)

Invasive plant management in the McDowell Sonoran Preserve is a collaborative effort involving Scottsdale Fire, utility providers, Tonto National Forest, Maricopa County, and other regional partners. The goal is to protect infrastructure, improve wildfire control, and minimize ecological impact.

The Preserve follows an integrated pest management (IPM) system that combines multiple strategies:

• Prevention: Trail users are encouraged to brush off shoes, clothing, and bicycles before and after entering the Preserve to prevent seed spread and to stay on designated trails. Boot brushes are available.
• Proper Plant Identification
• Pre-treatment Mapping, Assessment, and Planning: Treatment plans consider population size, location, and density.
• Treatment:
  • Mechanical: Hand-pulling plants or removing seed heads.
  • Chemical:
    • Post-emergent herbicides target and kill individual plants while sparing nearby native vegetation.
    • Pre-emergent herbicides prevent seed germination to maintain fire breaks and reduce fine fuel loads, while leaving established vegetation unharmed.
• Post-treatment Monitoring and Assessment
• Restoration: Native plant revegetation and seed dispersal.
• Repeat treatments as needed.

• Brush off your shoes, clothing and bicycles before and after entering the Preserve, especially if you have recently recreated or plan to recreate in other natural areas. The Preserve has boot brushes for this purpose. For more information: I Didn't Know That!: Boot Brushing
• Stay on designated trails.
• Be aware and stay clear of City of Staff, Volunteers, or Contractors who may be treating invasive plants
• Help eradicate invasive plants from the preserve by becoming a McDowell Sonoran Conservancy Steward.

Herbicide applications in Arizona are regulated under Arizona Revised Statutes Title 3 (Agriculture), Chapter 20 – Pest Management Division, and related Arizona Administrative Code rules. Requirements include:

• Use of certified applicators licensed by the Arizona Department of Agriculture
• Detailed recordkeeping for each application (site, date/time, product name, and EPA number)
• Adherence to label restrictions and federal standards under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)

The city maintains full compliance through annual applicator certification, accurate reporting, and adherence to best management practices.

Product labels and MSDSs

Product labels and MSDSs are available upon request. Contact the City for information on herbicide chemicals used in the Preserve.