Skaneateles Conservation Area/Invasive species/Pyrus calleryana

Pyrus calleryana (Callery pear)
The Callery pear (Pyrus calleryana), including its 'Bradford' cultivar, is now listed as highly invasive in New York State. There is a single known Callery pear present at the SCA near the fishing pond. It appears to have been planted sometime around 2003, shortly after the pond was expanded. This tree has not been removed (as of Sep. 12, 2021). It does not appear to be spreading at this time but there is evidence that the species is rapidly becoming invasive in much of its horticultural range in at least the eastern United States.

Invasiveness ranking for Pyrus calleryana (Callery pear)
The 2008 assessment gave Pyrus calleryana a score of 54/83 = 65.06%, which gave it a New York invasiveness rank of Moderate.

As of 2021, the New York Natural Heritage Program gives Pyrus calleryana a New York invasiveness rank of High and places it in State Tier 4 and Finger Lakes Tier 4.

Pyrus calleryana is not yet regulated by New York State law.

Callery pear is present and listed as a Tier 4 invasive plant in the Finger Lakes PRISM.

1. Ecological impact (13/20)
1.1. Impact on Natural Ecosystem Processes and System-Wide Parameters: Unknown (U)


 * As of 2008, analysis of herbarium specimens indicated a recent shift from the lag-phase to the spreading phase of this species, so the ecosystem-level effects have yet to be examined.

1.2. Impact on Natural Community Structure: Significant impact in at least one layer (7/10)


 * Recent field observation have shown this species to be rapidly invading fields, thus creating a canopy layer where one was absent.


 * Once established Callery pear forms dense thickets that push out other plants including native species that can’t tolerate the deep shade or compete with pear for water, soil and space.

1.3. Impact on Natural Community Composition: Influences community composition (3/10)


 * Definitely out-competes with native spp. in areas where it invades.

1.4. Impact on other species or species groups: Minor impact (3/10)

2. Biological characteristics and dispersal ability (19/22)
2.1. Mode and rate of reproduction

2.2 Innate potential for long-distance dispersal:

2.3. Potential to be spread by human activities:

2.4. Characteristics that increase competitive advantage:

2.5. Growth vigor:

2.6. Germination/Regeneration:

2.7. Other species in the genus invasive in New York or elsewhere:

3. Ecological amplitude and distribution (15/21)
3.1. Density of stands in natural areas in the northeastern USA and eastern Canada:

3.2. Number of habitats the species may invade:

3.3. Role of disturbance in establishment:

3.4. Climate in native range:

3.5. Current introduced distribution in the northeastern USA and eastern Canada:

3.6. Current introduced distribution of the species in natural areas in the 8 NY PRISMs:

4. Difficulty of control (7/10)
4.1. Seed banks:

4.2. Vegetative regeneration:

4.3. Level of effort required: