Short rotations speed up herbicide resistance evolution! This is because of the inherent lack of diversity.
Weed populations quickly respond to routine management practices – those that survive will set seed and their progeny have an advantage when the same control tactic is used again soon after.
Principle #1 Diversity in herbicide choices, diversity in cultural practices.
Target grass weeds in broadleaf crops and broadleaf weeds in cereal crops.
Add greater diversity to weed management strategies by adopting herbicide tolerance traits.
Principle #2 Create a low weed farming system.
Use break crops and double break crops, fallow and pasture phases to drive the weed seedbank down over consecutive years.
In summer cropping systems, use diverse rotations of crops including cereals, pulses, cotton, oilseed crops, millets and fallows.
Before herbicide selection has taken place it is very rare for an individual weed to be resistant to two herbicides. Mixing herbicides at full label rates in a single application takes advantage of this fact.
Within an integrated weed control program, try to make sure there is rotation and mixing going on in each phase – in the fallow, pre-seeding, in-crop and for desiccation. When done in conjunction with a determination to stop seed set and remove survivors, it is possible to keep weed numbers low.
Principle #1 Rotating buys you time, mixing buys you shots.
Rotate between herbicide modes of action groups.
Mix different modes of action within the same herbicide mix or in consecutive applications.
Principle #2 Follow resistance-prone herbicides with another tactic to control survivors in a fallow or pre-sowing situation and prevent weed seed set.
Incorporate multiple modes of action in a double knock. For example, glyphosate/Group 1/Group 2 knockdown followed by paraquat and Group 14 and pre-emergent herbicide.
Consider using a non-herbicide tool after resistance-prone herbicides to prevent seed set of survivors. For example, the ‘Canola Combo’ – crop top followed by harvest weed seed control (HWSC), or herbicide followed by tillage.
In cotton systems, aim to target both grasses and broadleaf weeds using two non-glyphosate tactics in crop and two non-glyphosate tactics during the summer fallow, and always remove any survivors (2 + 2 & no survivors).
Principle #3 Low dose applications result in herbicide resistance.
Always use full label rates.
Principle #4 Know what herbicides will and won’t work for you.
Test weeds for resistance and susceptibility to individual modes of action and mixes.
Spray drift is of great concern for sensitive crops and environments, along with the fact that if the spray doesn’t hit the intended target, you do your dough, and your weeds live. There are many factors to consider so every spray job is as effective as possible. Make every drop count.
Principle #1 Set up correctly to maximise efficacy and reduce spray drift.
Follow spray application guidelines and ensure the correct speed, nozzles, water volume, boom height, and adjuvants are used.
Avoid antagonistic tank mixes.
Principle #2 Hit the target.
Always use the largest spray droplet feasible that gives the highest efficacy.
Use the best quality water available. Test water quality and use adjuvants if required.
Avoid spraying during hazardous inversions (particularly from evening through to early morning), in high temperatures, frost and dew conditions, and when the wind speed is below 5 km/h or above 20 km/h.