Women in Ag day highlights weed issues

Women in Ag day highlights weed issues

Agronomists Helen Wyatt (left), Elders and Hilary Wittwer, Planfarm, at the Facey Group's recent Women in Agriculture day, where they led an interactive weed identification exercise and gave an agronomy update.

Agronomists Helen Wyatt (left), Elders and Hilary Wittwer, Planfarm, at the Facey Group's recent Women in Agriculture day, where they led an interactive weed identification exercise and gave an agronomy update.


Identifying weeds in the paddock or in your garden is the first step in making sure they are eradicated in the most efficient manner.


IDENTIFYING weeds in the paddock or in your garden is the first step in making sure they are eradicated in the most efficient manner.

And targeting weeds early, before they grow too big reduces the chance that they will set seed.

An agronomy session at the Facey Group's recent Women in Agriculture day involved a weed identification exercise, led by agronomists Hilary Wittwer, Planfarm and Helen Wyatt, Elders.

Ms Wyatt said there were many reasons growers needed to stay on top of weeds and that if left uncontrolled, they could easily reduce their income from crops.

"Weeds can contaminate your harvest sample as you are only allowed a certain amount of weeds in your sample, otherwise you'll be downgraded and it will cost you money," Ms Wyatt said.

"Another reason is crop competition - all those weeds that are growing in the paddock are stealing your fertiliser, nutrients and moisture.

"They are also going to set seed next year, so then there are more and more weeds.

"If we can tackle them while we have low numbers, then you'll be better off in the long run."

Ms Wyatt gave an example that if you had 20 ryegrass plants in a square metre, you would lose about 80 kilograms a hectare of yield in a cereal crop, which would cost you $24 a hectare.

"So the numbers can easily stack up," she said.

"Radish plants are twice as aggressive, so it will steal twice as many nutrients.

"You only need 10 radish plants in a square metre to give you that same yield loss."

Ms Wittwer said getting to weeds earlier would make it easier for farmers at the time and in the long run.

"The earlier you get weeds, the better, both for spraying and digging them out," Ms Wittwer said.

"Once you see them flowering, they are generally already setting seed, so you have probably missed the boat.

"Weeds with four to six leaves is probably the latest you want to leave it or they will start getting harder to kill."

Although looking for weeds while they developed sounded like an onus task, Ms Wyatt said there were simple ways to spot them earlier on, before they have flowered.

"One of the best places to look for weeds is between your rows, so that will be what you haven't sown," she said.

"So if you look down your rows as you're driving across, that's when you should dig them out, especially grasses in cereal crops as they can be hard to spot.

"Look for things that aren't normal, such as a patch of grass of different colouration, which is usually a good indicator that there is a different species robbing its nutrients.

"Also, look on the corners of your paddocks where the boomsprayer might have gone a bit quickly and might have missed."

While it is best to target weeds when they're young, they can also be more difficult to identify, but Ms Wittwer and Ms Wyatt shared some features to look out for to help identify them in the early stages of growth.

Weed leaves are split into two categories - broadleaf and grass leaf - and they germinate differently.

When broad leaf weeds germinate, the seed pops up above the surface and opens up - these leaves are called c-leaves or cotyledons.

Then they will unfurl and the true leaves will come up.

When grass leaves germinate, the seed stays underground and the leaf comes up from that.

Features to help identify weeds include:

Broad leaf weeds:

Canola: a bottom-shaped cotyledon and the leaves are soft and rounded.

Radish: a heart-shaped cotyledon with hairy, more jagged, veiny leaves.

Sow thistle: elongated oval cotyledons and the leaf edges are spiny and toothed.

Capeweed: a long, spiny cotyledon all the way to the base.

The first pair of cotyledons are long, jagged, fleshy and have hairy leaves, then they form a rosette (stemless).

Marshmallow: an 'ace of spades' shaped cotyledon with veins and a purple edge.

It has wrinkly Pac-man looking leaves.

Clover: oval cotyledons on stems.

The first leaf is round, then trifoliate leaves (three leaves on one stem).

Grass weeds:

Silvergrass: has a white base and rolled leaves.

Ryegrass: has a purple base and the leaves are shiny, folded leaves with a crease.

As it emerges more the leaves unfold.

Barley grass: the leaves are brighter.

It is fluffy and the seed has multiple spikes.

Brome grass: the seed is large, pointy, spikey and elongated with a purple tinge.

The leaf has small hairs.

Wild oat: the first leaf is large and the seed is a black oat.

Look inter-row for this one and it looks very similar to crops.

Both women also gave a brief agronomy update.

"Most of the crops were sown dry so we did not get a knockdown, which equals lots of weeds in crops," Ms Wyatt said.

"In comparison to last year, we are probably about a year behind.

"In terms of fertiliser, we usually like summer rain to get some of our stubble breaking down to get some nitrogen mineralising so it's available to our plants, but we didn't have any summer rain so we are expecting to have some low levels of nitrogen.

"The crops are still quite young, so we are probably not really seeing it what we have put down with our seeding fertiliser but we are expecting to see that pressure come on if people haven't put that top-up nitrogen on yet."

In regards to insects, Ms Wittwer said the most difficult problem she has faced that wasn't expected was insect pressure earlier on "because the crops came out of the ground later".

"(While) they have been small we have had large hatchings of red legged earth mite, which do a lot of sucking damage to those plants and lucerne flea, which chew and can make windows.

"This year, a lot of people have been caught out - whether they have used insecticides or not - just all the egg hatchings of when those bugs are germinated coincided with small crops, so a lot of people have had to do an extra spray just for bugs."

In the coming weeks, Ms Wittwer said agronomists would mostly be watching for disease.

"If we get a nice soft finish and even in the next coming weeks if we get more rain, potentially disease could start to build up in crops and that would be the next thing we are controlling.

"Most people are on top of their weeds now and we are looking at timing a second spray to potentially take any germination of these weeds, which can come up later, and coincide that with putting on a fungicide to protect the plant and keep it healthy going forward."


From the front page

Sponsored by