Red thread disease

Key takeaways

Red thread disease belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Red thread disease to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Red thread disease from memory before moving on to harder problems.

Reference excerpt

Red thread disease is a fungal infection found on lawns and other turfed areas. It is caused by the corticioid fungus Laetisaria fuciformis and has two separate stages. The stage that gives the infection its name is characterised by very thin, red, needle-like strands extending from the grass blade. These are stromata, which can remain viable in soil for two years. After germinating, the stromata infect grass leaf blades through their stomata. The other stage is visible as small, pink, cotton wool-like mycelium, found where the blades meet. It is common when both warmth and humidity are high. Environment Laetisaria fuciformis, the fungus that causes red thread disease develops more often in cool (59–77 °F (15–25 °C)) and wet conditions.1 These conditions are more present in the spring and fall when rainfall is higher and temperatures are slightly lower. Over 77 °F (25 °C), the growth rate of the fungus decreases significantly, and it ceases at 85 °F (29 °C).8 Turf grass that is poor in nutrition and are slow growing are areas that are more susceptible to red thread disease.2 The fungus grows from the thread like red webbing structures called sclerotia.1 The sclerotia can survive in leaf blades, thatch, and soil for months to years. These areas that have been infected spread the disease by water, wind, and contaminated equipment.1 Since this fungus can survive for long periods of time it is essential to cure the infected area so further spreading of the disease does not occur. Management Managing red thread disease first starts by providing conditions that are not favorable for the fungal disease to develop. Having a balanced and adequate nitrogen fertilization program helps suppress the disease.3 A light application of quick release nitrogen reduces disease severity and is generally the only treatment necessary on residential lawns.8 This includes applying mild to substantial amounts of phosphorus and potassium to the turf. Other than properly fertilizing the turf, it is very important to maintain a soil pH between 6.5 and 7.3 Having a more basic pH creates less favorable conditions for a fungus to form. Reducing shade on turf areas also reduces chances of the fungal disease to form because shaded areas create a higher humidity near the turfs surface.3 Another technique to suppressing red thread disease is top dressing with compost.4 Suppression of the disease increases with the increase of compost used on the turf.4 Another way to protect the grass in the area is to overseed with resistant varieties of turfgrass. Several resistant varieties of perennial ryegrass, fescues, and Kentucky bluegrass are available.8 Fungicides are not recommended to control red thread because the cost of chemical control is expensive and turf grasses usually recover from the disease quickly. 1 If the use of fungicides is necessary, products containing strobilurins can be applied and can be very effective if applied before symptoms occur.1 Hosts and symptoms The hosts of the red thread disease only include turf grass. Turf grass is primarily present on home lawns and sports fields. Some of these turf grass species include annual bluegrass, creeping bentgrass, Kentucky bluegrass, perennial ryegrass, fine fescue, and bermudagrass.5 These species of grass are not the only types of turf that can be diagnosed with red thread disease but are the most common hosts.5 Noticeable symptoms of red thread disease are irregular yellow patches on the turf that are 2 to 24 inches in diameter.6 Affected areas are diagnosed with faintly pinkish web like sclerotia on the leaf blades.6 This sclerotia is the fungus growing on the leaf blades.6 This sclerotia has a reddish to pink spider web look to it. The sclerotia are branched and they may extend up to 0.4 inches (10 mm) beyond the end of the leaf tip. 7

Identification The first signs of infection are small irregular patches of brown/yellowing grass. Upon closer inspection, either the tiny red needles or the pink fluffy mycelium will be visible. As the infection spreads, the small patches will join to form large brown areas.

Treatment Feeding the lawn with a nitrogen based fertilizer will help the grass recover and help prevent future attacks. Sources differ about treatment of Red Thread with benzimidazole fungicides, especially benomyl and carbendazim. Pennsylvania State University Extension recommends thiophanate-methyl alone among benzimidazoles but some reviewers describe benzimidazoles as universally beneficial to the pathogen and so detrimental for treatment of red thread. The infection will rarely kill the grass, usually only affecting the blades and not the roots, and the lawn should recover in time. References 1) Ryzin, Benjamin Van. “Red Thread.” Wisconsin Horticulture, 23 June 2013, hort.uwex.edu/articles/red-thread/ 2) Harmon, Philip, and Richard Latin. “Red Thread.” Purdue Extension, Dec. 2009, www.extension.purdue.edu/extmedia/bp/bp-104-w.pdf. 3) “Red Thread.” Plant Protection, NuTurf, nuturf.com.au/wp-content/uploads/sites/2/2015/09/Red-Thread-Info.pdf. 4) “Suppression of Soil-Borne Plant Diseases with Composts: A Review.” Taylor & Francis, www.tandfonline.com/doi/abs/10.1080/09583150400015904 5) “Red Thread — Laetisaria Fuciformis.” Red Thread (Laetisaria Fuciformis) - MSU Turf Diseases.net - Disease Identification and Information. A Resource Guide from the Dept. of Plant Pathology at Michigan State University, www.msuturfdiseases.net/details/_/red_thread_14/. 6) “Lawn and Turf-Red Thread.” Pacific Northwest Pest Management Handbooks, OSU Extension Service - Extension and Experiment Station Communications, 4 Apr. 2017, pnwhandbooks.org/plantdisease/host-disease/lawn-turf-red-thread. 7) Smiley, Richard W., et al. Compendium of Turfgrass Diseases. Third ed., The American Phytopathological Society, 2007. 8) Dicklow, M. Bess. “Red Thread and Pink Patch.” Center for Agriculture, Food and the Environment, 4 Oct. 2019, ag.umass.edu/turf/fact-sheets/red-thread-pink-patch.

References

External links http://www.lawnandmower.com/red-thread-disease.aspx Archived 2019-10-12 at the Wayback Machine http://www.grassclippings.co.uk/RedThread.pdf

Illustrations

Worked examples

Example 1 — a first encounter with Red thread disease

Start with the simplest possible case. Write down what Red thread disease claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Red thread disease before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Red thread disease ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Red thread disease

In research: Red thread disease appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Red thread disease in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Red thread disease is common in secondary-school and first-year university syllabi. It links to neighbouring topics Fungal plant pathogens and diseases, so understanding it makes those chapters shorter.
In everyday life: Look for Red thread disease outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Red thread disease in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Red thread disease means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Red thread disease out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Red thread disease in simple terms?

Red thread disease is a fungal infection found on lawns and other turfed areas. It is caused by the corticioid fungus Laetisaria fuciformis and has two separate stages.

Why does Red thread disease matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Red thread disease?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Red thread disease.