What is it? And how can I prevent or treat it on my lawn?
Fungal Pathogen – Ophiosphaerella korrae
Spring dead spot is a turf disease that appears as bleached patches in your lawn, ranging from just a few centimetres in size to large patches sometimes over 1 metre in diameter. Circular patches of bleached, straw coloured dead grass appear in Spring as the dormant grass resumes its growth. Patches can also be found in Autumn and Winter after a series of unusually cool and/or wet days, as cooler temperatures along with additional moisture in your soil will provide the ideal conditions for this disease to spread.
What causes Spring Dead Spot?
The fungal pathogen (Ophiosphaerella korrae) attacks the roots, stolons and rhizomes of couch grass. The roots will begin to rot and become dark brown or even completely black. It is often found in locations where thatch is more than 1.2cm thick, and/or locations with poor drainage and low potassium levels.
Tests have shown a higher prevalence of spring dead spot in turf grass that has been subjected to increased applications of Nitrogen during the previous summer. So whilst it can feel rewarding to apply extra applications of high nitrogen fertilisers for additional green up, its not recommended to do so, it will be detrimental to overall plant health and can lead to spring dead spot.
Which grasses are susceptible?
It is more common in couch varieties, however, in Perth we do get it in Kikuyu and Buffalo varieties as well. Most of the time you will only see spring dead spot in lawns that are under intensive management being cut super low and frequently, so it is quite common to see it appear on golf courses. For the lawnies out there who love a manicured, low cut couch lawn, this is a disease you need to look out for.
What is the treatment for Spring Dead Spot?
Spring Dead Spot is quite difficult to control. Due to this, prevention can be better than cure. The most effective defence is good ongoing maintenance including an effective fungicide schedule.
Some actions you can take to prevent Spring Dead Spot are:
Fertilising in late summer/autumn
Fertilising during this time allows your lawn to store carbohydrates over winter, so that the turf can easily break dormancy when the temperatures rise again in spring.
Ensuring you have good drainage
Spring Dead Spot thrives in wet, moist conditions
Managing fertiliser levels
It is especially important to watch your nitrogen levels, as heavy application of nitrogen in the late summer can increase the severity of Spring Dead Spot the following spring.
Make sure you keep your thatch under control
Ideally this should be kept under 1.1cm
Following this, an effective fungicide schedule is also crucial to keeping Spring Dead Spot at bay.
We recommend Bumper fungicide. It is what we apply on the farm on all our lawn varieties including our couch, buffalo and kikuyu as a preventative. We apply this in late February, early March and again four weeks later in April. Remember this is better applied with a liquid wetter such as Bi-Agra.
Once you have applied fungicide to your lawn, it is then important to irrigate BEFORE the fungicide has time to dry on the leaf. Irrigating at this point will also help the fungicide to be taken up by the roots, providing long-lasting protection.
It is also highly recommended that you rotate your fungicides to help minimise the risk of resistance.
So what should you do if you notice signs of Spring Dead Spot on your lawn?
First thing will be to look at the quality of the soil and evaluate the following:
Thatch Build Up
Amount of Drainage
Once these issues are addressed, you then need to look at regular aeration and verti mowing, which can greatly increase the quality of the plant, enabling it to recover.
Recovery will take some time as the patches are usually completely dead and it will require the spread of stolons back into the patch which can take almost the entire growing season.