Ability to Respond Total:16 / 25Ability to Respond = ( Ease of Response + Tools in Place )
Confidence:High
Confidence Notes:There are numerous studies and outreach materials on garlic mustard
Impact
Spread
Notes
Score
Spread Rate
The first infestation was found in California in 2020. In forested areas it has spread aggressively. It should be limited in many southern and central parts of the state. Seeds spread easily.
4
Spread Amount
Grows in upland and flood plain forests, savannas, yards and on roadsides. Seeds need to be cold stratified and germinate in moist to wet soils. Local spread is aggressive. Could spread in northern CA, and higher elevation forests across state
3
Damage
Notes
Score
Ecological
In other states, garlic mustard aggressively out competes native species in the understory of forests and woodlands. It is a biennial, overwintering rosettes of this plant resume growth in early spring when many native forest wildflowers are also active
4
Agricultural
Alters forests understory, can inhibit tree seedlings in dense infestations, can reduce forest wildflowers.
1
Infrastructure
0
Cultural
0
Health
0
Benefit
Notes
Score
Ecological
While several pollinators use this species it appears some butterfly larvae eat the leaves, but cannot mature on it.
0
Agricultural
0
Infrastructure
0
Cultural
0
Health
Garlic mustard is reported to be edible, however the local water quality and pathogens in riparian areas may override.
0
Total
12
Ability to Respond
Ease of Response
Notes
Score
Detection
The plant is difficult to detect at a distance, rosettes look like several other herbaceous plants growing in forests. Plants can grow or disperse downstream in remote forested areas which would be difficult to detect.
3
Control
Appears to be fairly difficult to control in other states. Foliar application of herbicide can be used to control large populations. Mechanical methods are slow but effective on small populations. Seeds persist over ten years in soil.
2
Tools in Place
Notes
Score
Entry
CDFA "A" rated weed
3
Control
CDFA "A" rated weed
5
Outreach
Outreach beginning in California, now that it is present. There is a good deal of educational materials in other states where the plant is a problem and can easily be adapted locally.
