Summer/Autumn Diseases in New Zealand Turfgrass
With the changeable conditions we have had in the first half of the summer season there have been conditions created favouring turfgrass disease.
Now according to NIWA our weather is still going to be mixed with continued “La Nina” like conditions, bringing more rainfall to the Eastern parts of the country and dryer weather to the west.
Anthracnose (Colletotrichum): Just one of the many nasties that are out to ruin your turf.
Image of (Acervuli) a fruiting body of Anthracnose (Colletotrichum).
The Current Weather Sends a Warning
Wet weather associated with warmer summer temperatures sets us up for disease. The difficulty to have dry surfaces during warm days create that ideal environment for disease to develop.
New Zealand geography is such that we are made up of many microclimates and so your area and the turf you manage will be unique and have unique disease issues.
The following is detail on diseases most common at this time of year in New Zealand turfgrass.
Prevention of disease will save your turf AND your budget.
Brown Patch (Rhizoctonia solani)
Symptoms
Circular patches of brown, wilted grass that can expand up to 1 meter in diameter. Affected grass may have blackened roots.
Favourable Conditions
Warm, humid weather, particularly in poorly drained, high thatch profiles.
Cultural Practices
Improve soil drainage, reduce thatch through aeration, and avoid overwatering.
Recommended Fungicide
Headway Maxx with Velista as a follow-up, if required.
Dollar Spot (Clarireedia jacksonii)
Symptoms
Small, circular, straw-colored spots about 25 – 40mm. Lesions may have a reddish-brown border.
Favourable Conditions
Warm days and cool nights with high humidity, especially in nitrogen-deficient turf.
Cultural Practices
Maintain adequate nitrogen levels, reduce leaf wetness by watering in the early morning, and improve air circulation.
Recommended Fungicide
Posterity reapply in 14 days, if required.
Rust (Puccinia spp.)
Symptoms
Grass blades develop orange or yellowish powdery pustules, resembling rust on metal. Infected areas may appear thin and weak.
Favourable Conditions
Periods of high moisture and slow grass growth, often due to low fertility.
Cultural Practices
Enhance turf vigour through proper fertilisation, mow regularly to remove infected leaf tissue, and irrigate deeply but infrequently.
Recommended Fungicide
Headway Maxx
Pythium (Pythium spp.)
Symptoms
Yellowing or thinning turf in irregular patches, wilting and decline, especially in wet conditions. Roots appear brown, water-soaked, and lack healthy white root tips.
Favourable Conditions
Hot, humid weather with prolonged leaf wetness, especially in areas with poor air movement.
Cultural Practices
Improve drainage, increase air circulation, avoid over-fertilisation with nitrogen, and water early in the day to allow foliage to dry.
Recommended Fungicide
Headway Maxx
Anthracnose (Colletotrichum cereale)
Symptoms
Yellowing and thinning of turf, with black, spiny structures (acervuli) on stems and leaves. Can affect both leaves and crowns, leading to plant death.
Favourable Conditions
Stress, such as high temperatures, drought, or over-watering and low fertility.
Cultural Practices
Alleviate plant stress by raising mowing heights, ensuring adequate irrigation, and providing balanced fertility.
Recommended Fungicide
Velista followed up with Headway Maxx if necessary.
Red Thread (Laetisaria fuciformis)
Symptoms
Patches of grass with a reddish-pink tinge. Red or pink thread-like structures may be visible on infected grass blades.
Favourable Conditions
Cool, damp weather, often with nitrogen-deficient soil.
Cultural Practices
Fertilise appropriately to address nitrogen deficiencies.
Recommended Fungicide
Headway Maxx if necessary.
Microdochium Patch (Microdochium nivale)
(Also known as Fusarium)
Symptoms
Small, water-soaked patches that enlarge and turn brown. Pinkish fungal growth may be visible in humid conditions.
Favourable Conditions
Cool, damp weather with prolonged leaf wetness. Excess thatch or over-fertilization with nitrogen.
Cultural Practices
Reduce thatch and avoid excessive nitrogen applications in late autumn. Improve drainage and airflow.
Recommended Fungicide
Headway Maxx
Fairy Rings (Basidiomycete fungi)
Symptoms
Circular rings of dark green, fast-growing grass or patches of dead grass. Circular rings of dark green, fast-growing grass or patches of dead grass. Mushrooms may appear in the affected area. Mushrooms may appear in the affected area.
Favourable Conditions
Well-drained soils with high organic matter.
Cultural Practices
Aerate soil and reduce organic matter. Apply wetting agents to break up hydrophobic soil.
Recommended Fungicide
Velista washed into the soil following an application of Terafirm or Tricure.
Spring Dead Spot (SDS) (Ophiosphaerella spp)
A serious disease of warm-season grasses, particularly couch (Cynodon spp.), but it can also affect other warm-season species. Caused by soilborne fungi and appears when the turf emerges from dormancy in spring.
Symptoms
Circular or irregular patches of dead turf, typically ranging from a few centimetres to over 1 meter in diameter. Infection in autumn when root growth is slow. Symptoms traditionally appear from September onwards in dry & cold winter climates but can appear all through winter in wet winter climates. More severe on the back of wet and cool weather (prolonged rainfall) in autumn.
Favourable Conditions
This disease is typically found where thatch is more than 1.2 cm thick and in locations with poor drainage and low potassium levels. Heavy applications of nitrogen in late summer often increase disease severity the following spring.
Cultural Practices
Use nitrate forms of Nitrogen for autumn applications. Prevention is the only real option, manage and prevent stress as much as possible. Start on a preventative program before autumn soil temps get to below 20⁰C
Recommended Fungicide
Posterity repeated in 28 days.
Aid Turf Recovery from Disease with MP Energise and MP Vitalise
Significantly improve Disease Recovery by applying MP Energise @10L/ha with MP Vitalise @20L/ha either as a tank mix with the fungicide or following fungicide applications.
Disease issues on your site are specific ones so please reach out to your Living Turf Technical Sales Rep for rapid and accurate Disease Identification, plus a bespoke program to prevent and/or cure your specific problem.
And remember, prevention is always the best approach. Both economically and agronomically.
For more information about Disease Prevention, Cure, and/or any of the products mentioned above, please contact your friendly Living Turf Technical Sales Agronomist.
Living Turf® is a subsidiary of Greenshed Pty Ltd, an Australian business that also boasts leading brands including; Precision Turf®, Greenspace 4D®, Turf Forensics®, MATCHplay®,Challenger® Turf Seeds, The Lawn Shed®, and LawnOnline®.