A 30% response rate was obtained for the 2011 survey, giving a similar number of actual responses (528) to 1985 (581), although not all respondents answered every question in the survey.
Occurrence, spread and duration of presence
Some 88% of respondents had at least a small amount of the weed on their farm (Table 1). The overall percentage of respondents across the eight original regions with large or moderate amounts of the weed increased from 51% in 1985 to 63% in 2011.
In 1985, fireweed was most likely to be absent, or present in small amounts, on farms in the Bega and Shoalhaven regions. By 2011, the proportion of respondents with moderate to large amounts of fireweed had increased substantially (especially in the Bega region), indicating that fireweed had become a more serious problem in both regions, and to some extent in Muswellbrook and Lismore (Table 1). In the previously relatively heavily infested regions of Taree, Gloucester and Hexham, near to where fireweed first became established in Australia, there was little apparent change in the weed’s occurrence. It had become a less serious problem, and was most likely to be considered under control, in the Cumberland region.
Of the four regions not previously surveyed, fireweed was entrenched in 2011 in the South-East Qld and the Mid-North Coast regions, and less so in the Northern Tablelands region. The pattern of occurrence in the Southern Tablelands region in 2011 was similar to that in its neighbouring region of Bega in 1985, with few small to moderate infestations and most farms free of fireweed (Table 1).
Table 1
Occurrence of fireweed by region, as a percentage of total response, in 2011 (12 regions) and where sampled in 1985 (eight regions; in brackets).
| Absent | Small amounts | Moderate amounts | Large amounts | Under control | n (2011 only) |
South-East Qld | 14 | 37 | 30 | 8 | 10 | 99 |
Lismore | 2 (0) | 13 (29) | 57 (46) | 25 (10) | 3 (15) | 60 |
Mid-North Coast | 0 | 35 | 38 | 11 | 16 | 37 |
Northern Tablelands | 35 | 50 | 9 | 6 | 0 | 34 |
Taree | 0 (0) | 17 (18) | 59 (48) | 14 (17) | 10 (17) | 29 |
Gloucester | 0 (0) | 25 (24) | 75 (59) | 0 (15) | 0 (2) | 16 |
Muswellbrook | 5 (29) | 23 (56) | 64 (9) | 9 (0) | 0 (6) | 22 |
Hexham | 0 (0) | 8 (21) | 72 (50) | 16 (19) | 4 (10) | 25 |
Cumberland | 30 (4) | 22 (35) | 22 (42) | 0 (13) | 26 (6) | 23 |
Shoalhaven | 0 (14) | 46 (43) | 19 (20) | 16 (4) | 19 (19) | 37 |
Southern Tablelands | 69 | 13 | 13 | 0 | 6 | 16 |
Bega | 11 (65) | 24 (25) | 18 (2) | 32 (0) | 16 (8) | 38 |
Total, 2011 regions*, ** | 12 | 28 | 37 | 13 | 10 | 436 |
Total, 1985 regions*, † | 5 (10) | 22 (30) | 46 (40) | 17 (11) | 10 (9) | 250 |
chisq = 216.7, d.f. = 44, p = < 0.001 (2011 data only) |
* Totals include respondents not providing a postal code and whose response is therefore absent from regional results.
** Totals include percentage response and n using all 12 regions included in the 2011 survey.
† Totals include percentage response and n from the 2011 survey using only the subset of eight regions included in the 1985 survey, with 1985 total percentage response data provided in brackets for comparison.
Of those respondents with fireweed on their farm, 18% observed its arrival within the last five years, while 33% had it on their farm for more than 20 years (Table 2). Amongst the eight regions included in both surveys, the duration of fireweed presence had increased, with a higher proportion having fireweed on their farm for greater than 20 years, and fewer respondents having fireweed on the farm for less than 10 years in 2011 than in 1985. The increase in the duration of fireweed presence was particularly sharp in Shoalhaven and Bega, where it had not been considered present for more than 10 years at the time of the 1985 survey (Table 2). Relatively high proportions of respondents from Southern Tablelands, South-East Qld, and Northern Tablelands had fireweed on their farm for less than 5 years in 2011. In contrast, fireweed had infested all surveyed farms in the Gloucester and Hexham regions (Table 2), with no new farms infested within the 5 years prior to 2011.
Table 2
Duration of fireweed presence by region, as a percentage of respondents with the weed in 2011 (12 regions) and where sampled in 1985 (eight regions; in brackets).
| Less than 5 years | Between 5 and 10 years | Between 10 and 20 years | Between 20 and 30 years | More than 30 years | n (2011 only) | |
South-East Qld | 43 | 35 | 16 | 4 | 2 | 83 |
Lismore | 2 (29) | 7 (29) | 38 (25) | 26 (7) | 28 (10) | 61 | |
Mid-North Coast | 8 | 39 | 22 | 25 | 6 | 36 |
Northern Tablelands | 36 | 23 | 18 | 23 | 0 | 22 | |
Taree | 4 (14) | 18 (50) | 29 (36) | 21 (0) | 29 (0) | 28 |
Gloucester | 0 (0) | 19 (27) | 19 (49) | 19 (22) | 44 (2) | 16 | |
Muswellbrook | 5 (63) | 14 (8) | 29 (25) | 14 (0) | 38 (4) | 21 |
Hexham | 0 (4) | 0 (13) | 16 (28) | 24 (38) | 60 (17) | 25 | |
Cumberland | 13 (62) | 25 (36) | 25 (2) | 31 (0) | 6 (0) | 16 |
Shoalhaven | 8 (89) | 28 (11) | 42 (0) | 17 (0) | 6 (0) | 36 | |
Southern Tablelands | 83 | 17 | 0 | 0 | 0 | 6 |
Bega | 27 (94) | 35 (6) | 21 (0) | 15 (0) | 3 (0) | 34 | |
Total, 2011 regions*, ** | 18 | 23 | 25 | 17 | 16 | 384 | |
Total, 1985 regions*, † | 7 (29) | 17 (29) | 30 (28) | 21 (10) | 25 (4) | 237 | |
chisq = 206.6, d.f. = 44, p < 0.0005 (2011 data only) |
* Mann-Whitney U Test p < 0.0005. Total includes those who did not provide a postal code and whose response is therefore absent from regional results.
** Totals include percentage response and n using all 12 regions included in the 2011 survey.
† Totals include percentage response and n from the 2011 survey using only the subset of eight regions included in the 1985 survey, with 1985 total percentage response data provided in brackets for comparison.
Of those respondents with fireweed on their farm, slightly fewer overall considered it to be their worst weed in 2011 than in 1985, however, there were large increases in Bega and Muswellbrook (Table 3), both of which in 1985 had many respondent farms free of the weed (Table 1). In contrast, the percentage of farmers rating fireweed as their worst weed had fallen considerably in Taree and Gloucester (Table 3), where the weed was present on all farms included in the 1985 survey (Table 1).
Table 3
Number of respondents considering fireweed to be their worst weed on farm, as a percentage of respondents with the weed in 2011 (12 regions) and where sampled in 1985 (eight regions; in brackets).
| Worst weed | Not worst weed | n (2011 only) |
South-East Qld | 33 | 67 | 122 |
Lismore | 23 (36) | 77 (64) | 79 |
Mid-North Coast | 40 | 60 | 79 |
Northern Tablelands | 23 | 77 | 25 |
Taree | 28 (77) | 72 (23) | 70 |
Gloucester | 14 (54) | 86 (46) | 18 |
Muswellbrook | 24 (8) | 76 (92) | 36 |
Hexham | 44 (46) | 56 (54) | 44 |
Cumberland | 27 (48) | 73 (52) | 28 |
Shoalhaven | 58 (51) | 42 (49) | 104 |
Southern Tablelands | 40 | 60 | 8 |
Bega | 56 (6) | 44 (94) | 126 |
Total, 2011 regions*, ** | 35 | 65 | 383 |
Total, 1985 regions*, † | 36 (43) | 64 (57) | 232 |
chisq = 26.5, d.f. = 11, p = 0.005 (2011 data only) |
* Total includes those who did not provide a postal code and whose response is therefore absent from regional results.
** Totals include percentage response and n using all 12 regions included in the 2011 survey.
† Totals include percentage response and n from the 2011 survey using only the subset of eight regions included in the 1985 survey, with 1985 total percentage response data provided in brackets for comparison.
Perceptions of problem status
Half of the respondents in 2011 considered fireweed to be either no problem or a minor problem, with the remainder perceiving it to be a moderate to major problem (Table 4). It was particularly notable that 70% of respondents from Bega considered it a moderate or major problem in 2011, up from 19% in 1985. A similar result was recorded in Muswellbrook. Respondents from the ‘core’ fireweed regions of Taree and Gloucester, and the more recently infested areas of the Northern and Southern Tablelands, were amongst the least likely to perceive it a major problem, though many still considered it a moderate problem. Only in Taree, Gloucester and Cumberland, was there an increase in the percentage of respondents between the two surveys considering fireweed not to be a problem. In all other regions, including Lismore and Hexham, there was an increase in the perceived problem status of fireweed (Table 4).
Table 4
Perceived size of the fireweed problem, as a percentage of respondents with the weed in 2011 (12 regions) and where sampled in 1985 (eight regions; in brackets).
| No problem | Minor problem | Moderate problem | Major problem | n (2011 only) |
South-East Qld | 21 | 36 | 29 | 14 | 84 |
Lismore | 8 (19) | 34 (48) | 43 (19) | 15 (14) | 61 |
Mid-North Coast | 11 | 38 | 41 | 11 | 37 |
Northern Tablelands | 27 | 46 | 23 | 5 | 22 |
Taree | 10 (8) | 31 (33) | 52 (41) | 7 (18) | 29 |
Gloucester | 6 (2) | 63 (46) | 25 (43) | 6 (9) | 16 |
Muswellbrook | 5 (58) | 55 (28) | 35 (14) | 5 (0) | 20 |
Hexham | 4 (19) | 32 (27) | 44 (48) | 20 (6) | 25 |
Cumberland | 20 (10) | 40 (41) | 27 (37) | 13 (12) | 15 |
Shoalhaven | 11 (26) | 44 (34) | 25 (19) | 19 (21) | 36 |
Southern Tablelands | 0 | 60 | 40 | 0 | 5 |
Bega | 6 (52) | 24 (29) | 18 (5) | 52 (14) | 33 |
Total, 2011 regions*, ** | 12 | 38 | 34 | 16 | 387 |
Total, 1985 regions*, † | 9 (19) | 38 (36) | 35 (33) | 19 (12) | 235 |
chisq = 68.5, d.f. = 33, p < 0.0005 (2011 data only) |
* Total includes those who did not provide a postal code and whose response is therefore absent from regional results.
** Totals include percentage response and n using all 12 regions included in the 2011 survey.
† Totals include percentage response and n from the 2011 survey using only the subset of eight regions included in the 1985 survey, with 1985 total percentage response data provided in brackets for comparison.
The foregoing data indicated a potential relationship between duration of fireweed presence on farm (Table 2), the likelihood that farmers will consider it to be their most important weed (Table 3), and the extent of the problem (Table 4). Where fireweed had only arrived relatively recently, such as in the Northern and Southern Tablelands, it was less likely to be considered the worst weed on farm or thought of as a moderate or major problem. This result was similar in regions where it had been present for longest, such as in Muswellbrook, Gloucester, and Taree, though a relatively high proportion of those from Hexham still considered it their worst weed (Table 3).
Cross-tabulation analysis did show significant relationships between duration of fireweed presence, its rating as the worst weed, and the severity of the problem. Those respondents who had fireweed on their farm for between 5 and 30 years were more likely to consider it their worst weed (Table 5) and a moderate or major problem (Table 6) than those who had it for less than 5 years, or more than 30 years, with the peak being between 10 and 20 years (Fig. 2). The reverse was true for the assessment of fireweed as a minor problem or no problem at all (Table 6).
Table 5
Duration of fireweed presence by whether it was considered the worst weed on farm in 2011.
| Worst weed | Not worst weed | n |
Less than 5 years | 16.4 | 83.6 | 67 |
Between 5 and 10 years | 41.9 | 58.1 | 86 |
Between 10 and 20 years | 49.0 | 51.0 | 96 |
Between 20 and 30 years | 34.8 | 65.2 | 66 |
More than 30 years | 27.4 | 72.6 | 62 |
chisq = 21.5, d.f. = 4, p < 0.0005 |
Table 6
Duration of fireweed presence by perceived size of the problem in 2011.
| No problem | Minor problem | Moderate problem | Major problem | n |
Less than 5 years | 30.9 | 50 | 11.8 | 7.4 | 68 |
Between 5 and 10 years | 12.4 | 34.8 | 40.4 | 12.4 | 89 |
Between 10 and 20 years | 5.3 | 29.5 | 48.4 | 16.8 | 95 |
Between 20 and 30 years | 6 | 32.8 | 31.3 | 29.9 | 67 |
More than 30 years | 8.1 | 50 | 27.4 | 14.5 | 62 |
chisq = 63.8, d.f. = 12, p < 0.0005 |
Management
Of those respondents with fireweed on their farm, 76% attempted to control it using one or more techniques in 2011, and 80% in 1985. Hand weeding remained the most popular of the management techniques available in 2011 and was rated amongst the most successful (Table 7), although considered most relevant to smaller outbreaks, ‘spot control’ of occasional plants, or on smaller farm areas. Herbicide control of fireweed increased significantly from 1985 to 2011, though ratings of its success declined, with a relatively large proportion of 2011 respondents having only low to moderate success (Table 7).
Use of slashing or mowing declined significantly from 1985 to 2011 (Table 7), alongside low ratings for success in both 1985 and 2011. Respondents who had used it successfully noted that regular follow-up slashing was required to minimise flowering and seed-set. Cultivation was considered a relatively unsuccessful control method, and its low use declined further from 1985 to 2011 (Table 7).
Promoting competitive pastures was considered by 86% of respondents to provide moderate to high success and was relatively widely used (Table 7). Nonetheless, its use had not increased significantly since 1985, and the associated technique of reduced stocking rates to increase pasture competition was seldom used. Survey respondents using sheep or goat grazing to control fireweed considered it to be the most successful technique overall (Table 7). However, the proportion of respondents using this method in 2011 remained small.
Table 7
Use and success of fireweed control methods, as a percentage of respondents who attempted control in 2011 and where surveyed in 1985 (in brackets).
Control method | Level of use* (n 2011 = 298) | Level of success** | |
| | Low | Moderate | High | n (2011 only) |
Hand weeding | 75 (74) | 26 (37) | 29 (29) | 45 (34) | 242 |
Herbicides† | 49 (12) | 41 (22) | 47 (37) | 13 (41) | 143 |
Slashing† | 36 (68) | 37 (41) | 50 (46) | 13 (13) | 119 |
Cultivation† | 5 (19) | 38 (33) | 41 (54) | 22 (13) | 32 |
Promoting competitive pasture | 39 (35) | 14 (21) | 54 (37) | 32 (42) | 108 |
Reduced stocking rates | 8 | 28 | 55 | 17 | 29 |
Grazing with sheep or goats† | 7 (5) | 18 (11) | 36 (22) | 46 (67) | 22 |
* Percentage of respondents who attempt fireweed control.
** Percentage of respondents who attempt control by that method.
† Binomial test (Level of use) p < 0.0005.