Plantain is a broadleaf weed that was bred and developed as an alternative pasture when it was discovered it had a high nutritional value.
“It’s not clover – that’s the issue. There are plenty of on-label clover sprays such as Thistrol or Pulsar. Plantain, on the other hand, is actually on the “weeds controlled” on a lot of those chemicals.”
This means plantain reacts to chemicals such as phenoxies, a family of chemicals that when sprayed on broadleaf plants, induce rapid and uncontrolled growth, resulting in the plant “growing to death”.
The development of PG742 is likely to offer slightly better thistle control options, Dorward says. PG742 is an Agricom-bred plantain that has some phenoxy tolerance, allowing some phenoxies to be applied, which isn’t the case with Tonic plantain.
“PG742 is only new to the market, so we’re still testing the waters, but from what we have seen in trial work, thistle control looks promising.”
Weed control in establishing plantain and clover crops
When it comes to establishing a crop of plantain and clover, early weed control is the key for a successful crop and the common spray recommendations for broadleaf weeds haven’t changed much.
“Bentazone has been widely used in the last three to four years. It’s quite a soft chemical and is off-label for plantain but when applied under the right conditions – small weeds, lots of water, warm growing conditions – if you get all those ducks in a row then the results are generally very good.”
When weeds are too big or growing conditions are less than ideal (too cold and moisture stress), there is poor uptake of the chemical, producing average results.
“If you get weed control right in the first year, it allows the crop to establish a lot better, which gives you benefits in terms of growing more drymatter (DM) but also benefits in terms of weed suppression and ground cover, making it difficult for weeds to establish in the second year.”
Dorward says if you don’t get weed control right in that first year of a crop, you will be chasing your tail as weeds get larger and harder to control. Grass weed control is on-label and generally pretty successful with the sprays such as Clethodim and Haloxyfop-P.
“Weeds are competing for space, moisture, light and nutrients, so you need to be eliminating them to allow the crop to flourish and increase production.
Although in a low payout year this can be tough, Dorward says skimping on weed control, particularly during the establishment phase, would put farmers in a worse position later down the track, and end up costing money, quality and drymatter for years to come.
“It’s no different to a pasture system – the first three months are important for the longevity of that crop and sets it up for the years to come. We need to educate farmers that they are running an intensive system which requires more inputs, like spray and fertiliser, than a pasture system but it will generate greater returns.”
Weed control in established plantain and clover crops
Plantain doesn’t compete well with naturally seeding grasses such as browntop and Yorkshire fog which can limit production of plantain, meaning control of grass weeds on an annual or bi-annual basis is important. Broadleaf weeds and thistles are a big issue for both establishing and established crops and requires a bit of lateral thinking when it comes to tackling them. Bentazone is still largely used as the base chemical, however spiking with other off-label proprietary products in order to overcome the poor uptake of Bentazone alone can help, particularly on hairy thistles such as scotch thistles.
“With established crops you generally have more grass weeds and bigger thistles which are harder to kill. So we are using Bentazone with different spikes depending on the paddock and weed situation.”
The main thing to remember is every paddock is different and you have to treat it that way, Dorward says. The rate and type of chemical recommended varies year-to-year and for weed type and size, temperature and growing conditions.
“We have found that in some cases Bentazone and a spike followed by topping a few weeks later proved really effective on large scotch thistles, which can be hard to control. Bentazone tends to have a better uptake on waxy thistles (nodding, variegated, winged). With hairy thistles like scotch thistles the uptake is pretty poor, hence why we have had to play around with spikes.”
Spring control of thistles can work well but is often a difficult time because of high feed demand and often a lack of spare paddocks. Late autumn control of thistles can be most effective because thistles are seedlings and feed demand is slightly lower than in spring.
“Farmers often stay off their paddocks in the winter to set them up for calving or lambing so pre-winter can provide a good opportunity to control weeds.”
Dorward says the key message for weed control on established plantain and clover crops is sometimes it has to be approached with a bit of innovation, particularly when it comes to thistle control.
“Every paddock is different. There is no blanket spray recommendation that you use on every plantain and clover paddock. That’s where a good rep comes into play who has a good understanding of chemicals, spray timings etcetera.”
Plantain facts
- Higher palatability than ryegrasses
- High protein and mineral content
- High digestibility of 75% (vs. 55% for ryegrass)
- Rapid fractional degradation rate (2.5 hours to 50% degradation vs. six hours for ryegrass)
- Responds best to rotational grazing but can also be set-stocked
- A prolific re-seeder, meaning the crop will often get stronger as it gets older
- Increased cool season drymatter production
Key messages for plantain and clover crops
- Spray weeds early
- High water rate
- 15C air temperature
- 12C soil temperature
- Active growth to ensure better chemical uptake
- Spraying when weeds and thistles are small
- Consult with your agronomist to get the best advice for your crop
