Controlling and Managing Nutsedge On Farm

We have a farm project in Northern Turkana, Kenya, with nutsedge weed as a major issue. Searching for cost effective techniques (non-chemical) to manage and control it. Tough to get rid of. Using switchback hoes. Tried tilling better prior to planting and drying. Do not have cultivating/tilling machinery. They only have very basic handheld hoes. Thoughts???

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Nutsedge is indeed a very difficult weed to control. Yellow (Cyperus esculentus) and purple (Cyperus rotundus) nutsedge are the two species often problematic in agricultural landscapes. They are most easily distinguished by their yellow and purple inflorescences (flower clusters), respectively. They reproduce mainly by below-ground tubers, each of which can have multiple buds that sprout to form new plants. Yellow nutsedge produces tubers on the ends of rhizomes while purple nutsedge produces tubers in chains. Tubers can exist in a dormant state and sprout when conditions are favorable. Depending on depth, they can persist in the soil for as long as 3 years (Mohler et al., 2021). For these reasons, nutsedge is hard to control.

There are some things you can do, though, to manage nutsedge. Nutsedge is sensitive to shade, so anything you can do to shade it out will help. Strategies include:

  • Planting crops with tall canopies, like maize or green manure/cover crops (velvet bean, jack bean, lablab [once established], and pigeon pea [long duration varieties produce large, dense leaf canopies]). Among vegetables, taller growing species like tomato will compete more strongly with nutsedge than shorter-growing crops.
  • Optimizing in- and between-row crop spacings to shade the ground quickly
  • Doing some hand weeding early on to allow the main crop to overtop the nutsedge early in the growing season.

Though minimal tillage helps preserve soil structure, it is good to at least be aware of the potential for tubers to dry out with dry-season tillage that brings them to the soil surface. Solarizing soil with plastic is possible but requires lots of sun; if there are too many cloudy days and temps are not high enough to kill the tubers, the resulting leaf blades will pierce right through the plastic. I’ll end with a link to info about pigs rooting out nusedge: Using Pigs to Root Out Nutsedge | The Pig Site.

Would be interesting to hear of others’ experiences.

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Hey Henry,

Firstly, why don’t you want chemical solutions? Because they are not available or you imagine them to be costly or you don’t want to promote them?

Secondly, please post a photo of what you mean by a “switchback hoe”. I’m not sure what you mean and hand hoes and standing hoes can vary a fair bit from country to country.

Also, do they have donkeys, cows or camels they could use or are already using for draught power and they are just not cultivating with them?

Also, what is the soil like… and the terrain, is it hilly, mountainous, flat, savanna… also, what are the main crops they are growing and in what proportions.

I.e What would they be willing to rotate with and to what degree.

What is the annual rainfall?

Is mulch/ organic matter/crop reside readily available and heap or scarce and already used for other purposes?

What are the current methods farmers use to get rid of it? Have any people got success stories to share? What advice to farmers give you or local Ag agents if there are any?

Sorry to ask more questions than give answer but knowing some of the content I think will help people to give you more helpful answers.

Nutsedge has been a problem in a number of places I’ve worked too… I wish I had a ready made and easy answer for you! I’ll be watching this post with interest and give it some thinking as I need to work out something for an area of my own farm which is struggling with it too.

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I had good success managing nutsedge a few years ago by intensively controlling it in one small area at a time. I was working in an area where we couldn’t use mulch due to pest pressure. A densely planted cover crop of sorghum-sudangrass and sunnhemp crowded and shaded it so it wouldn’t grow (it seems shade is nutsedge’s worst nightmare). Where I wasn’t able to cover crop, I did a quick sweep with a stirrup hoe every 1 or 2 days until the tubers ran out of energy and stopped popping up (maybe 10-15 days). This was mainly purple nutsedge if that’s useful. It’s definitely a very aggressive weed, so best of luck!

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Tim, Dave & Emma,
Thanks so much and grateful for responding.

Tim,

  1. The shading impact is an interesting thing to consider. They do grow tomatoes and I have not asked whether the nutsedge is less prominent in those areas. If so, we should incorporate this into the crop planning strategy. Growing cover crops will also help the soil as well, so I like this approach very much.
  2. Solarizing soil is another possibility as it is very hot and arid in this area. So those tubers would die quickly out quickly. Cover plastic is not readily available and could be expensive. However, they might be able to shift plastic around tough areas or something like that.
  3. Unfortunately, no pigs in this area but there are goats. Not sure if this is a viable option.

Dave,

  1. Chemical are expensive and we don’t want to promote them.
  2. Switchblade Hoes
  3. No donkeys, cows or camels. No large animals.
    4.The weather there is well into the 90’s. There is little rainfall. They have a good solar power pump system using elevated water tanks. Water is delivered through a water drip irrigation system. The area is flat. Soil is decent. Main crops are watermelon, tomatoes, cow peas, butternut squash, onions, peppers, spinach.
  4. Organic material is not readily available. They do collect goat poop for composting.

Emma,
A combination of different approaches seems to be a common theme. Unfortunately, these rural farmers have poor access to good tools and supplies to improve crop yield. However, we are making progress with providing sound advice people like you.

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If you have enough rainfall for mucuna beans, try those. They will smother anything, they can even kill creeping grasses.

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The nuts of nutsedge have been found 6 metres down when digging a well and still viable.

Once I pruned around a hedge of syzigiums (with 100-120mm trunk diameter at ground level) giving dense shade ( making them about 10-15 years old in a subtropical climate.)
Within a fortnight (summer) new shoots of nutsedge had shot up and a short time later it was a dense patch of sedge. Shade is very effective but remove it and they are back quickly.

I have grown field sweetcorn and sunflower with it with minimal impact from it as far as I could determine.

A side issue - when ‘roundup’ first came on the market it was claimed by the manufacturer that it killed 6 nuts in a chain and chemically broke down in a short time.
It has been found in the clay layer 40 years later. A landscape client once told me he viewed it as ineffective at destroying nutsedge and he claimed it increased the vitality of the plant after multipul usage over years … (Interesting?) (Was this resistance?).

It travels with nuts hanging off any traveling agricultural equipment which is how I suspect it arrived in this garden when a dam was being constructed 30 years earlier.
I consider it can travel on the inside of potatoes when the shoot has pushed through and formed a nut inside. I have cut a potatoes in half more than once to find a nut inside - a good awareness because what a person usually does is cut the nut out and throw it aside possibly uncut, undamaged and still viable.

It was shared to me by a farmer that as the pH increases from acid that favors it in my climate towards pH 7 it becomes less thrifty and tends to die back.
The opposite of putting compost and mulch on an acidic soil which is what we are doing. One would need to do a lime based pH adjustment for this to have impact I suspect.

So… what am I doing with the patch of it that is invading the gardens?

Nuts and whole plants have been collected and dried.
They were then burned in a pot with a lid on over a hot fire to ashes.
(With intent to demanifest life force in this species.)
A small portion of the ash each fortnight in a watering can is being watered over the nutgrass with the intent to “demanifest the life force in this species with the boundry that is being treated”.

This method I have used on seeding species with 99% success in the past.
A farmer told me that they had used it on nutsedge with the result that the sedge became very thin and unthrifty and no longer competition for the annual crops.

I am in the process of doing this currently - I can update with my observations with photos as this proceeds.
Meanwhile you may also choose to do it and evaluate outcome. Minimal to loose - cost is cheap and minimal labour.

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a ps I grind the ash finely and shake it in a bottle of water (well labeled) thoroughly before adding a little into the watering can. There are astrological timings that I have read that give better outcomes. Sometimes I use them and sometimes I don’t - depends on how urgent to get the project started.

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Hi again Henry,

Been thinking about this a bit as I go about with other jobs and was wondering - how has the nutsedge got so bad? One thing is to think about their farming system as a whole (over a few years) and consider how its getting so bad and see if you you can’t find the weak link in the chain… and fix it!

Some questions to consider:
Are they good at controlling early weeds but then bad at controlling weeds late season in a crop?
Are there ever long fallows or seasons where they are preoccupied with other work and just let their land grow weeds and the weeds multiply?
Are they farming larger areas then they can keep up with the weeding for and are having to abandon areas / just can’t keep up with the weeding to the point weeds are able to seed?
Is there a gap between the harvesting of one crop and the weeding/ ground preparation for the next that allows the nutsedge to reproduce…
Don’t just consider the time when the crop is in the ground but the whole year round… when and how is the nutsedge multiplying?

Try and have a look at the farms around and considering their farming system as a whole and see if that gets you anywhere.

Is cowpea forage sold there? You mention there are goats and goats love it. Its a valuable commodity in some countries. I grew cowpea as a forage crop this year. It yielded about 2 tons /ha and one can double their money with (here) but that was using rainy season rain. I would doubt it could compete in profitability to those veggie crops unless their farming standards are super low - which given they are using drip irrigation and solar pumps I’m guessing isn’t the case. Anyhow. If you wanted to try a cover crop. I recommend cowpea. As you’ll know it pops out of the ground in no time. Seeing as you have drip irrigation you could drill it in shallow and dense…(50cm between rows or even denser) and it will pop out of the ground and get to canopy closure pretty quick. You can google “NSW DPI cowpea forage guide” for some growing tips if it sounds promising. I planted mine dense in the row but about 100cm between rows so I don’t get row closer as fast but it still produced well - it even produced a fair bunch of beans. If one cuts off the forage after a time they can be left for seed and be dual purpose.

To be honest, Emma’s advice sounds the best in terms of just… persistently keeping at it. I’ve heard tigernut which is related to it can re-sprout around 7 times… so I imagine nutsedge would be similar. One could go for stale seedbed… and just water the ground and weed it for a few weeks but thats not free either. I know when I worked in a project some years ago the locals said the best way to get rid of it was just to reach down deep with your fingers and take out the nut… but that’s time consuming alright!

Regarding solarization - I tried that once as I heard its used in Isreali organic greenhouses. It effectively cooks your soils and will reduce disease levels… but… will also fry soil life too if that bothers you… I know some people look at it different ways so just be aware of it. Some people sterilize their potting compost for propagation trays while others are all about getting as much biotic life in their soils as they can. Anyhow, one could solarize with a frame that they move a bit like a chicken tractor but I think it would take about 3 week in each place and I reckon nutsedge seeds could be deep and hardy.

I’m surprised you say they don’t have any large animals! How do they cart things around? With cars? Is that everyone in general though or just you? And do all the farmers their use those switchblade hoes? Or is that what you guys are using? They look cool don’t get me wrong, I think I’ll have to try one out - its just they look like something from the West and not an African tool like I’m used to seeing! I think you must be in a much more developed area than I’m used to… if they don’t have large animals… and they have drip irrigation, do they have rototillers? Wow. most farmers there are using drip irrigation - impressive. I wish we could get it affordably here, its the best when it comes to irrigation efficiency. Could you introduce the donkey?! One doesn’t have to cultivate deeply with it … animals can just make weeding a lot faster (and more economical) - that said, navigating drip tape could be tricky, depends on your row configuration.

Good luck with it all!

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Mulching: Use organic mulch like straw or dried leaves around your crops to smother the nutsedge and prevent it from getting sunlight, which it needs to grow.

Hand Pulling: Since you have handheld hoes, allocate time for regular hand pulling of nutsedge weeds. Make sure to pull them out completely, including the roots, to prevent regrowth.

Crop Rotation: Rotate crops regularly to disrupt the nutsedge growth cycle. Some crops may naturally suppress nutsedge growth.

Cover Crops: Plant cover crops that compete with nutsedge for resources and space. This can help in suppressing weed Example: ablab,canavaria, cowpeas, Velvet Bean etc…

Solarization: Cover the infested area with transparent plastic sheeting during hot seasons. This heats up the soil and kills weed seeds and roots, including nutsedge.

Intercropping: Planting crops closer together can shade the soil, making it difficult for nutsedge to thrive.

Soil Amendments: Improve soil health and competitiveness of desired crops by adding organic matter like compost.

Manual Soil Disturbance: Use your switchback hoes strategically to disrupt nutsedge growth. Digging deeper and more frequently can help weaken its root system over time.

Community Engagement: Mobilize community members to help with weed control efforts, making it a collective responsibility and more manageable task.