Don’t get me wrong, there are a lot of disease posts that get put up on the app and plenty of them are genuine fungal issues. But I’m convinced a large percentage of them aren’t disease at all, and that’s worth talking about.
Yellow patches, brown spots, thinning. What looks like disease is often something else entirely: poor irrigation coverage, soil compaction, shade, dry edges, fertiliser overlap, fertiliser burn (especially in summer), scalping, dull mower blades, herbicide overdose, or even dog urine or the neighbour’s cat. The list is long.
Not every brown patch is a disease
Diagnosis is difficult because different problems can produce very similar symptoms. Healthy lawns are also full of fungi. Thousands of fungal species live alongside bacteria and the rest of the soil microbiome. Finding fungus in a lawn doesn’t automatically mean fungus is causing the damage.
Pattern matters more than colour
The pattern often tells you more than the colour. Is the damage in the shade? Does it follow an irrigation pattern? Is it where water sits after rain, or where people and pets regularly run? The shape and location of the damage can point you towards the cause faster than the colour ever will.
Why one photo isn’t enough
This is why a single close-up photo is rarely enough. It shows the symptom, but it doesn’t show:
- Recent weather conditions
- Irrigation practices
- Soil conditions
- Fertiliser history
- Recent chemical applications
- Mowing height and frequency
- The progression of the problem over time
What to include when asking for help
If you’re asking for help in the NZLA app, include a close-up and a wide shot, your grass type, what products you’ve applied recently, how you’re watering and mowing, how long the issue has been there, and whether it’s changing. A macro close-up photo of the leaf blade is also really useful, as it can show whether there are any lesions present.
That’s also where the NZLA journal in our app helps. When someone posts a problem, we can look back through their journal and see what they’ve actually been doing instead of guessing from a photo. Log the boring stuff. It becomes valuable the day you need help.
Stressed turf and product applications
Stressed turf and a foliar feed or a herbicide on top of it can be a bad mix. The product cops the blame when the lawn collapses, but the stress was there before the spray went on. A herbicide that’s safe on healthy, actively-growing turf can be rough on the same lawn coming out of waterlogging, or in the middle of a dry spell. Same goes for foliar feeds. If the lawn is already hurting, fix the conditions first and don’t pile product on top.
Before reaching for a fungicide, consider what’s changed and what’s stressing it. A lot of the time, the answer probably has nothing to do with a pathogen.
When it actually is fungal
Real fungal disease does show up. The markers are pretty consistent when it does. Lesions on individual leaf blades are one of the clearest. Discoloured patches with distinct edges, or banding across the leaf, point to real disease rather than wear or stress. Mycelium is sometimes visible early morning before it dries off. Damage that turns up fast after warm humid nights or a wet overcast stretch is worth taking at face value.
Circular or defined patch shapes that expand over time are another indicator, especially when the surrounding turf looks healthy. The conditions that drive disease are heavy thatch, low mowing heights, poor airflow, and night irrigation that leaves the leaf wet for hours.
When a fungicide is the right call
When the symptoms line up, the conditions have been right, and you’ve ruled out the non-fungal causes, a fungicide does the job it’s there for. Apply to turf that’s otherwise in reasonable health. A fungicide thrown at a badly stressed lawn in poor growing conditions does a lot less work than one applied to a well-fed, well-mown lawn that’s run into a tough disease week.
Preventative applications make sense if you’ve had recurring disease in the same spot season after season. Curative applications work best when you catch it early. Waiting until half the lawn is gone before reaching for the bottle makes the job a lot harder.
When the weather pattern is lining up for disease pressure, NZLA Azoxy is the go-to preventative. You don’t need to use it many times a year, and resistance is real, so two applications maximum before rotating to NZLA Fungus Pro. Applied at the right time, it does the work.
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