What causes dead spots in lawn during Summer

Date Posted: 17 January 2018 

With temperatures soaring this week, it is a great opportunity to talk about the effect this can have on your lawn.

The combination of hot and dry weather often brings about an influx of customers wondering why they have random dead patches or an overall general patchiness appearing in their lawn.

The nature of these dead patches is as follows:

  • The dead patches are random in shape and size.

  • They can appear right in amongst lush and healthy areas of lawn.

  • Sometimes they are very sharply defined around their edges – almost like someone spilled something on your lawn and other times the whole lawn can take on a patchy effect where it fades from green to brown in different areas.

  • They appear in hot and or dry periods.

So… The problem we are dealing with in this blog is why do random dead patches appear in an otherwise healthy lawn during hot and dry periods of summer?  These patches appear even though you may be watering, fertilising and maintaining as you always have in the past, with good results. 

The reality is that lawn patchiness, whether it be a few very defined and localised spots through to an overall patchy lawn can be cause by many different issues such as poor maintenance, poor soils, disease, insects, mites… the list goes on. The point of this blog is not to diagnose the exact nature of your problem but rather to give you a starting point to address it because there is a culprit that causes patchiness during summer more than anything else. 

With over 25 years of experience in consulting on lawns, I can tell you that the most common reason for patchy lawns during hot and dry periods is non-wetting soils. A non-wetting soil is where a soil repels moisture instead of absorbing it.  Most soils don’t absorb water evenly. Even though you may water evenly across your lawn, the water will penetrate deep in some areas and shallow in others. This means that the root zone of your lawn will be deep in some parts and shallow in others (proportionate to how deep the water penetrates).  Most soils are susceptible to this regardless of whether you bought in fresh soil when you installed your lawn.

You can literally have a green section of lawn right next to a brown one and in that way, non-wetting soils have a random, patchy effect on your lawn which is why it’s so often confused with beetle damage or fungal disease. Water that lands on non-wetting areas in your soil either pools and runs off or evaporates rather than penetrating so no matter how much you water it, the water doesn’t make it to where it’s needed meaning those patches don’t recover. The irony is, even though your lawn may look like it needs a drink,  more water won’t solve a non-wetting soil problem.

What Causes it?

In most cases, non-wetting soils are caused up by the build-up of organic residues. These residues are a waxy like substances that coat the soil particles which in turn cause it to repel water. Organic residues occur when organic material in the soil breaks down over time.  Fungi in the soil can also lead to excessive build-up of organic residues.

How do you treat it?

Liquid wetting agents such as Paul Munns Betta Wet are the best way to treat non-wetting soils.  Wetting agents treat the non-wetting problems in soil ensuring that water penetrates evenly. 

So many lawn problems can be treated, if not solved with wetting agents. Here are just some of the advantages:

  • They ensure even water penetration

  • They ensure even nutrient distribution. Because water is the carrier of nutrient to the root zone, the deeper the water can go, the deeper it can take the nutrient, resulting in a deeper rooted, healthier lawn.

  • They treat non- wetting soils

  • They are great for water penetration on sloping areas. Instead of running down the slope, water will be more likely to penetrate in.

Liquid wetting agents do a couple of things – they help break down the waxy organic residues and they also coat the soil in an agent which makes the soil much more receptive to holding onto water molecules.

Unfortunately, you can’t really solve water repellent issues in soil indefinitely, you can only ever treat them. Wetting agents don’t last very long in the soil and you will find that in time, they need to be re-applied.

In my opinion, liquid wetting agents are the elixir of life for lawns and garden, whether you have non-wetting soil or not. They ensure that any rain or water penetrates evenly. They also reduce wastage of water because they make it possible for the water to penetrate quickly instead of evaporating or running off.

For what it’s worth, if you find yourself with a patchy lawn, the first thing I’d recommend is a wetting agent however If the problem persists, bring in a core sample for us to check for you.


Comments (3)

Patchy green / brown lawn

By: on 11 February 2019
Hi. How much Bi-Agra do I put in a 2 litre spray on container and what area of lawn would that cover. Thankyou. John

Paul Munns Instant Lawn Response
Hi John If your using the concentrated Biagra, you would pour 250ml of it into a 2L hose on container and then fill with water. This mix would cover 100 square metres.

Turf Mites?

By: on 8 February 2019
Hi Stefan My front kikuyu and rear couch lawns seem to be showing signs of dry/dead patches in random spots. I have tried applying soil wetting agents, soil conditioners and keeping a regular watering schedule but with limited results. Now I have noticed the tell-tale signs of turf mites, the so-called 'witches brooms'. What safe measures can I take to treat this problem? Thanks.

Paul Munns Instant Lawn Response
Hi Tony, Turf mites are a common problem in lawns and you could well have them. The only solution to this problem is to spray with an active ingredient called abermectin. The trade name for this is Thumper. Mites lay a prolific amount of eggs which have a 14 day hatching period. This means that you will need to spray twice - once to kill the existing mites and once again 14 days later to kill the mites that hatched. Regards, Stefan

Brown patch could it be brown patch?

By: on 12 February 2018
My lawn has a blue grey tinge and then looks dry and dead.kaye

Paul Munns Instant Lawn Response

Hi Kaye,

While its possible that you have Brown Patch, its unlikely. When lawn blades go a blue, grey colour it is mostly because the moisture is disappearing from the blade - ie patches of your lawn are drying out. This is probably because the soil is non-wetting or water repellant. Most soils dont wet evenly so when you water your lawn, some areas absorb the water and other areas dont. This is why you get a patchy effect. The areas that dont absorb the water dry out very quickly resulting in dead patches. 

I would suggest that you apply a liquid wetting agent 2 or 3 times at even intervals during the summer months. This will ensure deep and even water penetration and most likely solve your problem. 

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