Fleabane Control Demonstration Lockhart NSW (November 2011)

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Take Home Messages

  1. Aim to treat young Fleabane plants prior to tap root development. If unsure of the age of plants, dig them up and inspect the root system.

  2. Aim to treat plants when actively growing and free from stress.

  3. Glyphosate alone, in any form, will not give effective control of Fleabane, regardless of size or age.

  4. Once Fleabane plants have a fully developed root system, no single pass treatment will achieve better than 80% control.

  5. A “Double Knock” with Roundup + 2,4-D followed 10 days later by Gramoxone is the most reliable treatment once plants have reached this point.

  6. It is very important to include some hormone (2,4-D, Tordon or Lontrel) in the first application, however, if following with Gramoxone, high rates of hormone are not required.

Location “Woodend” Lockhart NSW

Aim To assess a range of chemical treatments for the control of Fleabane varying in age from 2 weeks to 6 months.

Spraying Date 22nd November 2011

Weather Conditions Overcast, 20°C, slight WSW breeze.

Weeds Present

  • Fleabane (winter germination) Multi-branched, 20+ leaves, significant tap root development 20 to 50 plants/m2

  • Fleabane (spring germination) 4-8 leaves, rudimentary root development 20 to 50 plants/m2

  • Hairy Panic (50-80 cm diameter)

  • Heliotrope (4-6 leaf)

  • Jersey Cudweed (5-10 cm tall)

  • Marshmallow (old, woody plants with large tap roots)

  • Sow Thistle (5-10 cm diameter)

Condition of weeds Younger Fleabane plants were under some soil moisture stress due to dry soil surface conditions. Heat stress not evident. Older Fleabane plants had been grazed by livestock.

Soil conditions Dry at the soil surface, stored moisture below 10cm

Treatments

  1. Roundup @ 1.5L/ha

  2. Roundup @ 1.5L/ha + Ally @ 5g/ha

  3. Roundup @ 1.5L/ha + Lontrel @ 300ml/ha

  4. Roundup @ 1.5L/ha + Tordon 75D @ 700ml/ha

  5. Roundup @ 1.5L/ha + Amicide 625 @ 500ml/ha

  6. Roundup @ 1.5L/ha + Amicide 625 @ 1.0L/ha (*Surpass 475 would have been the preferred option)

  7. Gramoxone was applied across a section of each treatment, 7 days and 14 days after initial treatments.

Application Details 4m Boom width 80L/Ha water rate AIXR 110-025 Nozzles 3 BAR pressure C to VC droplet spectrum 15kph travelling speed

Trial Layout

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Assessment Plant counts taken 21 days after initial treatments, or 7 days after second application of Gramoxone, to assess percentage control.

Results and Discussion

Table

Table

Single Pass Treatments

Roundup CT @ 1.5L/ha Controlled Hairy Panic, Heliotrope and Sow Thistle. Very little effect on Fleabane or Marshmallow

Roundup CT @ 1.5L/ha + Ally @ 7g/ha Improved results on Fleabane compared with Roundup CT alone. Young Fleabane (spring germinated, 6 leaf, 2 weeks old) were controlled. Older, winter germinating plants were severely affected, approximately half the size of untreated plants, with yellowing of the growing points. However, these plants recovered over time.

Roundup CT @ 1.5L/ha + Lontrel @ 300ml/ha Similar results to Roundup CT + Ally. Spring germinating Fleabane was controlled, while older plants were yellow and deformed. It was expected that the older plants would recover in time. Lontrel at this rate may give some residual control of Fleabane.

Roundup CT @ 1.5L/ha + Tordon 75D @ 700ml/ha Young plants were controlled, while older plants were stunted and twisted. As a single pass option, the knockdown effect on older plants is inadequate. Tordon 75D at this rate is claimed to give some residual control of Fleabane. This treatment was the most expensive in the trial.

Roundup CT @ 1.5L/ha + Amicide 625 @ 500ml/ha Young Fleabane plants were controlled well. The amount of 2,4-D applied in this treatment is inadequate as a single pass treatment on large, old fleabane plants that have a well developed root system. When using a “Double Knock” strategy, however, this is an adequate 2,4-D rate for a first pass treatment.

Roundup CT @ 1.5L/ha + Amicide 625 @ 1.0L/ha Significantly better results on old Fleabane compared to the 500ml/ha rate. All young Fleabane have been controlled and approximately 70% of the older plants have died. This result was significantly improved by a follow-up application of Gramoxone. It is important to note that when using Amicide 625 at these concentrations, there is significant antagonism between 2,4-D and Glyphosate, leading to sub-standard results on Hairy Panic and Sow Thistle.  Amicide was used in this demonstration becuase Surpass was not available on the day of spraying. A Glyphosate compatible 2,4-D should always be used when mixing the two products.

Double Knock Strategy

Gramoxone @ 1.5L/ha applied 7 & 14 days after initial treatments Applications of Gramoxone at both 7 and 14 days vastly improved the control of Fleabane when compared to single pass treatments.

Results were slightly better in the 14 day application compared to the 7 day application. This is due to the earlier application desiccating the plants before hormones in the first application have time to take effect.

The Roundup CT alone and Roundup CT + Ally treatments only managed to achieve 50% and 70% control respectively, even when using the double knock strategy. This reinforces the importance of including a hormone product in the first application.

Despite differences in the single pass treatments, Amicide 625 @ 500ml/ha gave equal results to Amicide 625 @ 1.0L/ha when followed by Gramoxone.

CroppingLiz KelleherRural Management Strategies