Pest Control in Lawns without using chemicals – Is it possible?
Author: Stefan Palm Date Posted: 1 March 2022
It’s a question we get asked regularly from people who have genuine concerns over whether off the shelf chemicals will have an effect on not only themselves but wildlife, pets, livestock and the earth in general.
Care for our environment has definitely increased in recent times. There is certainly more awareness that the long term and indiscriminate use of chemicals can have unintended consequences.
Many of the chemicals that you buy off the shelf in hardware stores and garden centres may have some undesirable side effects. While they may control uninvited pests in your lawn, their long term is only now starting to be understood. For example, research suggests that some chemicals such as Dicamba (an active ingredient in some selective herbicides) can damage the roots of nearby trees and plants. Most chemical labels instruct users to dress head to foot in protective clothing and to restrict access till it has dried or has been watered in. Others recommend that you don't feed clippings to livestock or allow runoff into nearby waterways. When you start reading these labels, it's easy to understand why people want to consider alternatives.
It's certainly easy to turn to chemicals to solve pest problems in lawns. It's understandable considering they can provide a fast and effective solution to problems. It's not that all chemicals are bad and destructive to the environment either. The question is are there chemical-free alternatives or are there ways to use fewer chemicals?
The short answer to the question is yes - there are alternatives and there are ways to use less.
Maintain a healthy lawn
When considering lawn pests, you're talking about weeds, insects and disease. All of these have the potential to affect your lawn to a varying degree. The severity to which they affect your lawn will in most cases depend on how healthy it is. A healthy lawn can naturally sustain a pest attack better than an unhealthy lawn. Lawn competition is one of the most effective pest management control measures available to the home gardener. Pests take advantage of weak lawns and often thrive in poor conditions. While this may sound simplistic, it's absolutely true. Weeds will have less chance to take hold because they have so much competition from the lawn. Insects like beetles can eat their share of rootzone and the lawn will re-grow new roots at a faster rate than they are being eaten. Disease may be less severe and a lawn may be able to recover faster when soil conditions are right. I'm not saying that you won't experience pest problems in a healthy lawn and that you won't need chemical intervention to solve some problems. I'm simply saying that you'll have less problems and they'll likely be less severe.
Consider factors like:
- pH – ensure the soil under your lawn is pH neutral. This is the sweet spot for lawns because this is where the lawn is able to extract all the available nutrients in the soil. A soil that is either too acidic or too alkaline will lock out nutrients resulting in a less than healthy lawn. The other consideration here is that there are weeds that prefer acidic soil and weeds that prefer alkaline soil so going too far in either direction will swing the pendulum in favour of the weeds over the lawn. pH can be measured using a pH test kit – if you find that your soil is acidic or alkaline, you can adjust it with garden lime or powdered sulphur
- Fertilising. Make sure you are fertilising your lawn 3 times per year - mid-seasons except for winter. Aside from all the typical advantages of fertilising, it will help with weed, insect and disease management (see below). I would suggest Paul Munns Year-Round Fertiliser Program.
- Water management – Regular watering during the warmer months will help to keep your lawn in a healthy and strong condition. It doesn’t have to be excessive – but it does have to be consistent. The best advice I can give here is to water long enough to get moisture down to about 75mm below the surface at least once per week. You may need to apply a liquid wetting agent from time to time to make this possible as a large percentage of soils in Adelaide repel water instead of absorbing it. It makes sense that if you can get water down deep in your soil, then you can also make a way for lawn roots to grow down deep too. Deep roots generally equal a healthy and strong lawn.
- Mowing. Keeping your lawn mown often will encourage it to spread and stay thick and dense. Regular mowing will also keep weeds from flowering and seeding.
Ensuring your lawn is as healthy as possible will create an environment where your lawn will naturally suppress weeds. Having said that, there still will be times when weeds germinate and grow. When that happens, there are some key things that you can do to control them.
There are many chemical-free ways to kill off weeds and reduce weed populations – some very effective ones at that, however you'll need to be more tolerant of the odd weed and you'll also need to tip in more time to get rid of them. Its also worth noting that there are some very persistent and hard to kill weeds that will require some extra special persistence or at least some initial chemical treatment to reduce the population to a point that they can be controlled without chemicals.
Pay attention to weeds and manage weed populations before they get out of control. It’s much easier to tackle weeds when they are young, small and few in number. Removal techniques include the following:
- Pull them out. Sure this sounds simple, but anyone who has tried to keep up with weeds by pulling them knows that it’s not always so easy – some weeds are more easily pulled than others. The best time to pull weeds is when the soil is still moist from watering or rain. Pull slowly from the base of the weed to get the best chance of pulling a root out and make sure to use garden gloves for spiny plants like thistles. There are some fairly nifty weed pullers worth investigating too – some of them can even be used while standing up such as the Fiskars Xact weed puller. A word of advice, some weeds like creeping oxalis and clover have a runner type root system and can’t be pulled out easily.
- Scald them. Boiling water is another alternative way to control weeds. This is a non-selective method (ie boiling water will kill the lawn too) so be careful how you apply the water. Simply pour boiling water from a kettle onto the weeds – the heat will destroy the cell structure in the leaves and kill them instantly. Be careful of your hands and feet, and keep children and pets away.
- Use a non-chemical weed killer. There is a new range of fatty acid based products being released that you can use to spot spray weeds in lawns. They are non-selective (ie will kill lawn too) but they are a very effective control measure and are totally organic. Eco Organic has a product called Slasher that is certified organic. Click here for more info.
- Pre-emergent Herbicides. This is an initial chemical approach that leads to fewer chemicals in the future. Pre-emergent herbicides prevent weed seeds from germinating. Once you eliminate the seeds, you won't have a weed seed bank in the soil to germinate and perpetuate the weed problem into the future
The middle ground here is that you can manage weeds very effectively without chemicals in most situations however there may be circumstances where you need to use chemicals to get on top of a persistent weed problem. It may be the case that you use chemicals to clean your lawn up, eliminating all the existing weeds and weed seeds, then move on to a chemical-free program. I've written a few blogs lately on the use of pre-emergent herbicides that work on killing weed seeds so that they don't germinate in your lawn. By using one of these (such as Spartan) you can clean up your lawn making it much easier to employ chemical-free methods in the future - because from then on you will only be dealing with the odd weed or two rather than a persistent population. In that way, while you would use some selective chemicals in the beginning, your use from then on would be minimal.
There are some particularly damaging insects that love to eat lawn roots such as black beetle. One issue that I encounter time and time again is that when people see a dead or dying patch in their lawn, the first thing that comes to mind is that it must be lawn beetle. This thought is followed up with the application of one or several applications of beetle killer. I can tell you that after 30 years in the lawn industry there are times when beetles cause dead and dying patches in lawn however it is not as a common occurrence as you might think. If you experience dead and dying patches in your lawn, before rushing out to buy beetle killers, do some investigation to see if the problem is actually beetles. Dig a small inspection hole in one of the patches. If you find beetle larvae then you can confirm its beetle. If the soil is dry, then it's more likely a water-related problem. Statistically, for every 100 lawns we consult on for dead and dying patches, only five of them are caused by beetles or lawn insects. 65 out of 100 are caused by non-wetting soils - ie soils that repel water rather than absorb it. You'd be better off applying a wetting agent as a first response rather than beetle chemicals. It's less toxic and has a much higher chance of solving your problem. Once again, there are instances where chemicals may be necessary such as with mite control or if in fact you do have beetles however remember that a healthy lawn is the best first defence against soil insects.
Disease is rare in domestic lawns however it can happen and when it does, chemical control measures are often the only solution. It is certainly one instance where it is hard to avoid chemicals. Before applying fungicides, bring a core sample to your lawn specialist for identification so that the right chemical can be used.
In all, there are instances where chemicals may be required to control lawn pests however I do believe we can and should use less of them. In every instance where you are considering using chemicals, have a think if you actually need to. Could you live with some weeds? Are you targeting a problem that doesn't exist in your lawn? Could you maintain a healthier lawn?