Table 1.

Conyza canadensis populations and geographical regions sampled in California and the frequencies of plants that survived glyphosate treatment in each. Populations are sorted by latitude and habitat type

Pop'n ID	Population habitat	Latitude (N)	Longitude (W)	No. plants treated	No. plants surviving	R	SE	R per region	County	GWPA (km2)
Northern region
A1	Orchard: prune	39.589	121.801	89	3	0.03	0.020	0.07	Butte	3
A2	Orchard: almond	39.714	121.843	60	4	0.07	0.067		Butte	3
B1	Orchard: walnut	39.353	121.726	60	8	0.13	0.133		Butte	3
B2	Orchard: walnut	39.331	121.678	52	0	0.00	0.000		Butte	3
B3	Orchard: almond/walnut	39.106	121.689	50	1	0.02	0.017		Sutter	224
C1	Orchard: almond	38.951	122.060	40	0	0.00	0.000		Colusa	5
C2	Orchard: almond	39.012	122.070	60	1	0.02	0.017		Colusa	5
YOL2	Orchard: peach	38.707	122.075	60	14	0.23	0.200		Yolo	78
SON1	Vineyard: grape	38.671	122.813	78	10	0.11	0.059		Sonoma	36
Central region
E1	Vineyard: grape	38.169	121.202	50	27	0.53	0.075	0.68	San Joaquin	683
E2	Vineyard: grape	38.190	121.417	54	54	1.00	0.000		San Joaquin	683
F2	Orchard: cherry	37.821	121.108	51	50	0.98	0.024		San Joaquin	683
G2	Orchard: almond	37.610	120.755	67	59	0.86	0.055		Stanislaus	1219
G3	Orchard: almond	37.551	120.811	82	3	0.04	0.038		Stanislaus	1219
Southern region
H1	Orchard: almond	37.040	120.221	51	39	0.78	0.087	0.88	Madera	523
H2	Orchard: pomegranate	36.996	120.241	56	55	0.95	0.048		Madera	523
H3	Vineyard: grape	37.014	120.230	89	88	0.99	0.011		Madera	523
I1	Vineyard: grape	36.824	120.187	42	42	1.00	0.000		Madera	523
I2	Vineyard: grape	36.938	120.129	71	41	0.53	0.097		Madera	523
I3	Vineyard: grape	36.982	120.202	60	51	0.85	0.150		Madera	523
K1	Vineyard: grape	36.634	119.768	77	77	1.00	0.000		Fresno	1461
K2	Vineyard: grape	36.592	119.764	51	26	0.58	0.376		Fresno	1461
K3	Vineyard: grape	36.620	119.777	75	70	0.94	0.056		Fresno	1461
L1	Vineyard: grape	35.906	119.250	60	60	1.00	0.000		Tulare	1609
L2	Vineyard: grape	35.906	119.224	60	60	1.00	0.000		Tulare	1609
N1	Vineyard: grape	35.703	119.391	51	50	0.98	0.024		Kern	42
CSU	Orchard: peach	36.818	119.734	–	–	–	–		Fresno	1461
WES	Vineyard: grape	36.340	120.106	–	–	–	–		Fresno	1461
MCC	Vineyard: grape	36.638	119.611	–	–	–	–		Fresno	1461
KEA	Vineyard: grape	36.595	119.507	–	–	–	–		Fresno	1461
Nonagricultural habitats
MEN2	Roadside	39.179	123.683	60	0	0.00	0.000	0.07	Mendocino	3
AUB1	Roadside	38.972	121.106	90	3	0.03	0.019		Placer	140
YOL1	Roadside	38.938	122.225	51	2	0.04	0.007		Yolo	78
MEN1	Roadside	38.883	123.141	27	9	0.33	–		Mendocino	3
SAC1	Roadside	38.486	121.081	60	2	0.03	0.033		Sacramento	395
NAP1	Roadside	38.483	122.240	57	0	0.00	0.000		Napa	0
BOD1	Roadside	38.306	123.058	47	0	0.00	0.000		Sonoma	36
BOD2	Roadside	38.306	122.839	67	13	0.14	0.128		Sonoma	36
LIV1	Roadside	37.703	121.737	60	1	0.02	0.017		Alameda	0
MAR	Roadside	37.483	119.963	59	1	0.02	0.017		Mariposa	0
CRU1	Natural reserve	36.950	122.065	54	4	0.07	0.069		Santa Cruz	0
MON2	Roadside	36.436	121.630	90	16	0.18	0.048		Monterey	156
Control populations
R	Canal bank	36.488	119.403	193	185	0.96	0.022		Tulare	1609
S	Orchard	36.799	119.954	255	10	0.02	0.023		Fresno	1461

R, population‐level resistance to glyphosate estimated as the proportion of survivors out of the total number of plants treated with glyphosate at 840 g a.e. ha⁻¹, averaged over 2–3 replications.

Groundwater protection area (GWPA) per county available at http://www.cdpr.ca.gov/docs/emon/grndwtr/gwpa_lists.htm.

Resistant (R) and susceptible (S) controls from Shrestha et al. (2007).