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Anthracnose: Interactions with the disease triangle

Anthracnose: Interactions with the disease triangle: Anthracnose of turf is caused by the pathogen Colletotrichum cereale. The disease primarily affects intensely managed turf surfaces because of the considerable stresses that these environments place on the host plants.

This article describes phases within the lifecycle of anthracnose of turf (figure 1) in the context of the three aspects of the disease triangle; pathogen, host and environment.

Biotrophic phase

Simplified lifecycle of Colletotrichum cereale, the anthracnose pathogen that affects turfgrass.

Simplified lifecycle of Colletotrichum cereale, the anthracnose pathogen that affects turfgrass.

The pathogen establishes within the host without causing symptoms of disease.

  • Pathogen

During the biotrophic phase of the anthracnose lifecycle, the pathogen establishes itself within the host plant without alerting the plant to the requirement to respond defensively. It does this by extending primary hyphae, root-like filaments, between the plant cells without actually entering the cells. The pathogen further disguises its presence from the plant using a process called deacetylation, in which chitin on the hyphae is converted to chitosan (Muench, et al., 2008).

  • Host

The plant does not respond defensively to the pathogen because the hyphae do not enter the plant cells and the presence of chitin, which primes plants to activate defensive mechanisms, is hidden. However, even at this early stage of infection, the pathogen may affect its host negatively by creating a nutrient sink at the site of infection; thus, increasing the nutrients availability for the pathogen whilst reducing the nutrients that are fulfilling plant functions.

  • Environment

Extended periods of leaf wetness allow the pathogen to penetrate the host plant and for the biotrophic phase of development to commence. Practices that reduce leaf wetness; such as use of surfactants and physical removal of dews will help to reduce pathogen establishment at this stage.

Foliar blight on a Poa annua sward showing the characteristic yellowing of leaves and diagnostic black setae.

Foliar blight on a Poa annua sward showing the characteristic yellowing of leaves and diagnostic black setae.

Necrotrophic phase

The pathogen penetrates into plant tissues and disease symptoms are observed

  • Pathogen

Necrotrophic growth is characterised by the development of secondary hyphae which penetrate into plant cells. This growth is accompanied by the production of phytotoxins which degrade plant tissue, providing the fungi with a further nutrient source. This phase of growth for anthracnose pathogens which affect other plants typically occurs within 72 hours after the initiation of the biotrophic phase  (Mims & Vaillancourt, 2002). The exact timing is not yet known for Colletotrichum cereale, the pathogen that infects turfgrass.

  • Host

There are two distinctive forms of anthracnose infection during the necrotrophic phase; basal rot and foliar blight (figure 2). It is likely that this symptomatic variance is caused by infection occurring in different parts of the plant.

Foliar blight is characterised by yellow (Poa annua) or reddish (Agrostis stolonifera) lesions on leaves and a water-soaked appearance.

Basal rot is characterised by symptoms in the lower stem or root. The infected tissue at the base of the plant appears dark brown to black with the leaf sheaths above appearing orange to yellow but without foliar lesions.

  • Environment

Development of the disease into the necrotrophic phase is favoured by conditions that put the grass plant under abiotic stress; including low fertility, close mowing, compaction, heat, drought, low light levels and poor drainage. Historic records and weather forecasts are essential to determining when to undertake actions which will minimise the impacts of potential stressors on the plant.

Relevant stresses may be current or historical. For example, the considerable metabolic requirement in spring of Poa annua to produce seedheads takes photosynthate away from roots and shoots prior to a stressful time in the growing season and could weaken the host increasing its susceptibility to infection.

Colletotrichum spp grown in laboratory conditions on potato dextrose agar showing acervuli with diagnostic black setae producing conidia.

Colletotrichum spp grown in laboratory conditions on potato dextrose agar showing acervuli with diagnostic black setae producing conidia.

Reproductive phase

The pathogen spreads infective material to other areas

  • Pathogen

The reproductive phase begins with the development of fruiting bodies called acervuli within which the conidia, or spores, are produced (figure 3). Conidia can be transported on the wind or mechanically. Following contact with another susceptible plant, they can adhere to it by producing a suction cup called an appressorium. The pathogen then forces a highly specialised hyphae called a penetration peg into the plant resulting in the initiation of the biotrophic phase.

  • Host

During the reproductive phase black hair like structures known as setae which project from the acervuli on infected plant tissues are visible with a x10 hand lens. These structures are key diagnostic features for this pathogen when it develops as foliar blight (figure 2 & 3).

  • Environment

Warm, humid weather and increased light intensity are the primary environmental factors controlling the development of conidia. Laboratory studies indicate that Colletotrichum cereale produces conidia at temperatures between 24-32°C with increased maturity of conidia observed at 28°C compared with lower temperatures (Wang & Kerns, 2017). Once conidia have been excreted from the acervuli in a water-soluble matrix they can be spread by wind, water, or human activity but need continued leaf surface moisture to establish.

Research shows that wounding of the host plant through maintenance practices such as verticutting, top dressing and rolling does not increase the incidence of disease as the pathogen does not rely upon entry through wounds or weakened tissues due to its ability to develop a penetration peg.

This article has been written in conjunction with Dr Abigail Graceson and Tom Wood.

Dr Abigail Graceson

As a Technical Manager within the Agrovista Amenity Technical Department, Dr Abigail Graceson draws upon both her practical skills and academic research experience. In addition to her eight years’ experience as a professional gardener & horticulturalist; Dr Graceson spent nine years as a researcher specialising in horticulture, growing media and green roofs.

Tom Wood

Amenity specialist for the Yorkshire region, Tom Wood holds a first class bachelor’s degree in Sportsturf Science and Management (UCLan) which he combines with over ten years’ practical turf management experience. Over this time Tom has amassed a broad range of knowledge and skills sourced from a variety of fields including education, golf courses and technical sales.

References

Mims, C. W. & Vaillancourt, L. J., 2002. Ultrastructural characterization of infection and colonization of maize leaves by Colletotrichum graminicola, and by a C. graminicola pathogenicity mutant. Genetics and resistance, 92(7), pp. 803-812.

Muench, S. et al., 2008. The hemibiotrophic lifestyle of Colletotrichum species. Journal of plant physiology, Volume 165, pp. 41-51.

Wang, Y. & Kerns, J. P., 2017. Temperature effects on formation of appressoria and sporulation of colletotrichum cereale on two turfgrass species. International Turfgrass Society Research Journal, Volume 3, pp. 123-132.

More information on this subject can be found on the Agrovista Amenity Academy. The Agrovista Amenity Academy is an online learning resource with courses and lessons created on a range of areas of turf management and for all products sold by Agrovista Amenity.

For more information about Agrovista UK, visit www.agrovista.co.uk/amenity

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Maximise disease resistance this autumn

Maximise disease resistance this autumn: Greenkeepers, groundsmen and amenity space managers should apply more than just nitrogen, phosphorus and potassium to their green areas this autumn, with magnesium and iron essential to maintaining healthy, disease free grass throughout the winter.

That is the latest advice from Richard Brown, Amenity Sales Manager for Germinal GB, who, speaking at the SALTEX show on 30th October, recommends the application of specialist fertilisers to ensure grassed areas remain healthy as the weather turns cooler.

Maximise disease resistance this autumn

“No matter how naturally resistant a grass cultivar is to diseases such as fusarium, an unhealthy or nutrient deficient sward won’t be able to withstand the disease pressures associated with the onset of wetter and colder autumn conditions,” Mr Brown explains. “Greenkeepers, groundsmen and amenity space managers must therefore remember that feeding the sward goes beyond applying the main three macro-nutrients of nitrogen, phosphorous and potassium, and should apply additional micro-nutrients, namely magnesium and iron, to bolster tolerance to disease and cold conditions.”

Germinal’s specialist G13 Protekt and G14 Alleviate Fe fertilisers are formulated to provide the necessary nutrients to protect grass swards at crucial times such as during the onset of cooler autumn and winter conditions.

G13 ProteKt is a 3-0-22 (+3% Fe) anti-stress fertiliser. Containing 22% potash and 3% iron, it can be used during the autumn and winter to harden turf, heighten sward colour and prevent disease attack. Used at this time of year, G13 ProteKt enhances wear tolerance, protects the sward from frost damage and enables quicker recovery in the subsequent spring.

G13 ProteKt can also be applied in the spring and summer when its high potassium content aids transpiration control in dry periods and fortifies the drought tolerance of grass plants.

G14 Alleviate Fe is a 4-0-10 (+8% Fe) fertiliser which is ideal for protecting high value turf areas such as sports fields, golf greens and tees and bowling greens throughout the growing season, but especially during the autumn and winter months. G14 Alleviate Fe contains magnesium, a vital component of chlorophyll, which helps to maintain good metabolism of energy for healthy plant growth. Its high iron content improves resistance to disease and ensures quick greening throughout the growing season without causing any intense flushes of growth. G14 Alleviate Fe also helps to control and inhibit moss.

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Protect Against Disease This Autumn

Protect Against Disease This Autumn: Greenkeepers, groundsmen and amenity space managers should apply more than just nitrogen, phosphorus and potassium to their green areas this autumn, with magnesium and iron essential to maintaining healthy, disease free grass swards throughout the winter.

That is the latest advice from Richard Brown, Amenity Sales Manager for Germinal GB, who, ahead of the 30th October SALTEX show, recommends the application of specialist fertilisers to ensure grassed areas remain healthy as the weather turns cooler.

Protect Against Disease This Autumn

“No matter how naturally resistant a grass cultivar is to diseases such as fusarium, an unhealthy or nutrient deficient sward won’t be able to withstand the disease pressures associated with the onset of wetter and colder autumn conditions,” Mr Brown explains. “Greenkeepers, groundsmen and amenity space managers must therefore remember that feeding the sward goes beyond applying the main three macro-nutrients of nitrogen, phosphorous and potassium, and should apply additional micro-nutrients, namely magnesium and iron, to bolster tolerance to disease and cold conditions.”

Germinal’s specialist G13 Protekt and G14 Alleviate Fe fertilisers are formulated to provide the necessary nutrients to protect grass swards at crucial times such as during the onset of cooler autumn and winter conditions.

G13 ProteKt is a 3-0-22 (+3% Fe) anti-stress fertiliser. Containing 22% potash and 3% iron, it can be used during the autumn and winter to harden turf, heighten sward colour and prevent disease attack. Used at this time of year, G13 ProteKt enhances wear tolerance, protects the sward from frost damage and enables quicker recovery in the subsequent spring.

G13 ProteKt can also be applied in the spring and summer when its high potassium content aids transpiration control in dry periods and fortifies the drought tolerance of grass plants.

G14 Alleviate Fe is a 4-0-10 (+8% Fe) fertiliser which is ideal for protecting high value turf areas such as sports fields, golf greens and tees and bowling greens throughout the growing season, but especially during the autumn and winter months. G14 Alleviate Fe contains magnesium, a vital component of chlorophyll, which helps to maintain good metabolism of energy for healthy plant growth. Its high iron content improves resistance to disease and ensures quick greening throughout the growing season without causing any intense flushes of growth. G14 Alleviate Fe also helps to control and inhibit moss.

For the latest industry news visit turfmatters.co.uk/news

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Fighter Commando Combats Disease

Fighter Commando Combats Disease: Germinal has added a high phosphorous foliar fertiliser – which improves plant health and increases disease resistance – to its expanding range of amenity specific fertilisers and sward conditioners.

Fighter Commando is a 0-28-26 NPK* liquid fertiliser containing 28% phosphorous in the form of phosphite (P2O5) and 26% potassium as K2O.  It’s high P and K content stimulates lush, healthy plant growth and can actively help grass swards to withstand disease during periods of increased stress.

Fighter Commando Combats Disease

“Unlike other forms of phosphorous, phosphite is highly water soluble which means it can quickly be absorbed through the leaves and roots of grass plants,” explains Richard Brown, Amenity Sales Manager for Germinal.  “Once absorbed, Fighter Commando remains extremely mobile and acts systemically to rapidly correct potassium and phosphorous deficiencies, enhance root development and improve the plant’s natural ability to resist diseases.”

As well as improving plant vigour and reducing the sward’s susceptibility to disease, Fighter Commando is also environmentally friendly: “The chemical composition of Fighter Commando prevents it from binding with soil, therefore preventing an excessive build-up of soil phosphorous and eliminating problems associated with ground-water contamination,” Mr Brown adds.  “It is suitable for a range of amenity purposes, from sports pitches, golf courses, tennis courts and bowls greens, to fine lawns, parkland areas and any grassed area where a potential nutrient imbalance could threaten sward health and vitality.”

Fighter Commando is supplied in 10-litre containers and can be tank mixed with most pesticides.  It is recommended for use at an application rate of 5 litres/ha at 3-4 week intervals from March to October.

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Disease Management Trials

Disease Management Trials: This year’s STRI Research event will see Bayer continuing its study into disease prevention in pursuit of the best programme for tackling Microdochium Patch in light of recent losses to curative chemistry.

Dr Colin Mumford, Bayer technical manager, explains that the new research will build on results from last season’s set of trials, that showed preventative options outshone curatives.

Disease Management Trials

“This year the aim is to reinforce these findings and see how we can improve on current disease management programmes, with alternative and new products, as well as different application rates and timings.

“A variety of different fungicides will be put to the test, including Exteris® Stressgard® and Dedicate®, alongside a number of plant health promoting products, from two of our main distributors, Headland Amenity and Rigby Taylor,” he says.

“Once again, we’ll be testing the Microdochium Patch cover, colour and quality of the turf, with a variety of programmes including preventative fungicides, plant health products, and the last remaining curative options that mimic a more traditional approach.”

He points out that the conditions this year could be quite different to the low disease threat experienced by the STRI last season. “The turf has taken a bashing this summer, with prolonged periods of high temperatures and strong sunlight, so it’ll be very interesting to see how the turf fairs with a stressful start to the disease season.”

The trials are due to start in late August, to pre-condition the turf for improved health, and should run until spring 2019, to see if there is any effect on green-up ahead of the key playing season.

Colin explains that during the event, along with representatives from Headland Amenity and Rigby Taylor, the Bayer team will present on each of the combinations being applied to the plots, their regularity and the expected outcomes.

For more information, please visit www.environmentalscience.bayer.co.uk, Headland Amenity www.headlandamenity.com or Rigby Taylor www.rigbytaylor.com

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Headland Keeps School Disease Free

Headland Keeps School Disease Free: Thanks to help from Headland Amenity, the 17 hectares of grounds for rugby, tennis and cricket at Kings Bruton School have come through the winter of 2017 disease-free and stronger than ever before.  For a relatively small school, they punch well above their weight when it comes to sport and the facilities they offer their 350 pupils.

Grounds Manager, Adie Davis, and his team of 6 groundstaff are kept busy looking after the facilities. “I have been familiar with Headland products for a long time and have enjoyed success with their programmes here at the school for a number of years. On our cricket outfields & rugby pitches we’ve been using Multigreen 28-0-0 which delivers results for the full 5-6 months it promises it will.” Applied in April and then again in September for strength through the autumn/winter, this is complemented on the fine turf areas by C-Complex in various formulations: 4-3-4 used during renovation work; 7-0-7 through the cricket playing season and 5-2-10 as a spring-starter.

Headland Keeps School Disease Free

On the cricket squares, Adie has found success with the combination of Multigreen Mini and Headland’s 20/20/30 non-pesticidal tank mix. “We apply the Multigreen Mini in early autumn to take us through the winter and then once a month between October and March we supplement this with a spray of the 20/20/30 enhanced plant health mix.” Headland’s industry-leading 20-20-30 mix combines Seamac ProTurf Fe and Liquid Turf Hardener plant protectants and Turfite elicitor that work together to strengthen the plant against disease. The combination of products applied at Kings Bruton delivers enhanced root development, disease resistance and strong colour. “This programme has kept all disease, including Fusarium and Dollar Spot, at bay – which I know groundsmen at other schools are suffering from.”

As the school heads towards its 500-year anniversary celebrations in 2019, Adie is delighted with the success achieved with their current nutritional regime. “I’ve worked closely with Headland’s Alex Hawkes, who is very knowledgeable, for a number of years and it’s thanks to him that we now have a combination of products that are really working. We get a lot of comments from staff, parents and local clubs that they’ve never seen turf quite like ours, our cricket areas in particular, which makes all the hard work worthwhile.”

For more information, visit: www.headlandamenity.com

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Future Of Disease Control Tracked With New Live Maps

Future Of Disease Control Tracked With New Live Maps: A new disease forecasting tool on the Syngenta Greencast turf management website is now giving a clear picture of disease pressure across the United Kingdom – and predicts where there risk of infection is set to occur and will enable more informed actions.

Live Maps combine accurate weather forecast information along with proven disease prediction models, to foresee and track risks for up to five days before they occur.

Future Of Disease Control Tracked With New Live Maps

Encompassing Google maps, users simply zoom in to their own area for a close up of detailed local information. The maps cover all key turf diseases, along with forecast changes in soil temperatures and a new feature for Grass Growing Potential.

Daniel Lightfoot, Syngenta UK Turf Business Manager, enthuses that one of the great advances of Live Maps for greenkeepers is the ability to visibly track conditions and risks progressing across the country – and giving time to assess action plans.

“Targeting preventative disease programmes during periods of infection risk, but before symptoms break out consistently maintains better playing surface conditions,” he advocated.

Daniel pointed out that STRI research had shown fungicide programmes based on proactive forecasting maintained better conditions using fewer applications over the course of the season, compared to routine application or treatment at the first signs of disease.

“Timing is the absolute key,” he advised. “Live Maps is a new way to better pinpoint the optimum application timing.” He believed that turf managers are going to have to get ever better at prevention in the future, to mitigate the impending loss of iprodione and to meet the increasingly stringent demands of today’s players

“Whilst products such as Instrata Elite have excellent curative activity on early disease stages with in the leaf, the results are consistently better and longer lasting if it can be applied before symptoms have broken out on the surface,” he added.

Danial believes the new Grass Growing Potential maps will be especially useful for aiding Primo Maxx application interval timing – enabling turf managers to focus on periods of peak growth and potentially ease off when conditions are less favourable.

“If you use Grass Growing Potential in conjunction with soil temperature, it could be highly beneficial for timing renovation or over seeding activities to get seedlings off to the best possible start,” he said. “It also has a role for predicting turf recovery and implications for the disease management programme.”

The Live Maps are available now free for all registered GreenCast subscribers, under the ‘Weather’ tab in the navigation bar.

For more information go to www.greencast.co.uk

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Germinal Focus On Disease & Stress Resistant Bentgrass Mix At BTME

Germinal Focus On Disease and Stress Resistant Bentgrass Mixture At BTME: Grass seed and turf care specialists, Germinal, will be showcasing its latest greens-specific seed mixture at the BTME show in Harrogate from 23rd to 25th January 2018.

Designed specifically for use on soil or sand-based golf greens, FOREFRONT GREENS is a blend of three bentgrass varieties, all of which have been selected to offer increased wear and heat tolerance, vigorous growth and good all-round disease resistance for hard-working, modern golf greens.

Germinal Focus On Disease & Stress Resistant Bentgrass Mixture At BTME

Comprising 35% AberâRegal (Browntop Bent), 35% AberâRoyal (Browntop Bent) and 30% 007 DSB (Creeping Bent), Forefront Greens produces a sward with enhanced disease and stress resistance and which retains a superb year-round green colour.

AberRegal and AberRoyal are the latest UK-bred bentgrass cultivars to come out of the IBERS (Institute of Biological, Environmental and Rural Sciences in Aberystwyth) breeding programme: bred from material originally sourced from Kent and west Wales respectively, AberRegal and AberRoyal boast superb disease resistance, particularly to Fusarium, as well as excellent shoot density, fineness of leaf and unrivalled winter and summer greenness.

007 DSB was developed in the US using 24 parent plants to produce a single cultivar with a wide genetic base.  It is this background which enables it to deliver all the qualities of a top-rated Creeping Bentgrass (prostrate growth habit, high shoot density and good wear tolerance) in a range of conditions – from the extreme heat of Morocco to the harsh cold of Western Siberia.

007 has won plaudits wherever it has been used, including Ryder Cup and US Open courses, and has recently been announced as the variety of choice for the greens renovation ahead of the PGA Masters at Wentworth.

“AberRegal, AberRoyal and 007 DSB work well together by providing greenkeepers with a low input seed mixture with improved genetic diversity and a sward with higher resistance to key disease threats such as Red Thread and Fusarium,” explains Richard Brown, Amenity Sales Manager for Germinal.

“As such, Forefront Greens is the perfect solution for progressive greenkeepers who are currently managing browntop bents, but who are seeking extra performance from the same management inputs.  The unique combination of cultivars ensures soil and sand-based golf greens remain verdant throughout the year and, thanks to the inclusion of three top-performing varieties, avoids the risks associated with creating a mono-culture of grasses.”

AberRoyal, AberRegal and 007 DSB are available exclusively in the UK via Germinal.  The recommended sowing rate for Forefront Greens is 8 to 12g/m2 (80 to 120kgs/ha).  The recommended overseeding rate is 5 to 8g/m2 (50 to 80kgs/ha).

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