You May Not Come Across During Your Day to Day Greenkeeping but Dr

Feature L&D Feature

Golfers could get lost in the ‘rough’

You may not come across during your day to day Trawl the net for tropical weeds and you will find greenkeeping but Dr most consideration given to Terry Mabbett reveals, agriculture. It’s as though turf such is the vicious in the tropics does not suffer from weeds, but I can assure you nature of some tropical it does and with a vengeance. weeds, perhaps that is Weeds in the hot wet tropics smother turf and take over just as well! amenity grassland spreading from these sites to cover hard surfaces at phenomenal rates. No part of the tropical sports and leisure facility escapes. Weeds will infest greens, tees and fairways, turn any ‘rough’ into a veritable jungle and completely clog up streams, drainage ditches, ponds and lakes. Weed frequency, intensity and growth rate are exceptionally, high boosted by high temperature, humidity and soil moisture level. In regions lacking a dry season weeds grow and reproduce throughout the calendar year. Facilities in regions with a distinct dry season are given some respite but instantaneous bursts of weed growth with onset of the rains has to be seen to be believed, and requires prompt sustained control. Turf Managers in temperate countries face a seasonal resurgence of weeds, but this will pale into insignificance in the humid tropics where weeds move so fast you can almost see them grow. Many of the worst tropical weeds started life as ‘ordinary’ wild plants within restricted habitats and geographical distributions. Redistri- bution of plants by agriculture and horticulture during colonial times (18th and 19th centuries) spread lots of wild plants that subsequently acquired turf and amenity weed status throughout the tropics. Nowhere is this more true and apparent than in the Caribbean, his- torically most visited part of the world by man and plant alike. The following observations on weeds of turf and amenity grass were made in the twin island nation of Trinidad and Tobago southernmost of the Caribbean island countries and just a few miles off the coast of South America. These islands provide an ideal loca- tion to gauge the breadth of tropical turf and amenity weeds. Not only do they support weeds native to South Truly tropical America, to which Trinidad was once joined, but others from across the world introduced deliberately or accidentally, especially by The Impe- rial College of Tropical Agriculture (now the St Augustine Campus of The University of The West Indies) with its turf weeds roots way back in the 19th century.

46 GI DECEMBER 2011 DECEMBER 2011 GI 47 Feature L&D Feature

Golfers could get lost in the ‘rough’

46 GI DECEMBER 2011 DECEMBER 2011 GI 47 L&D Feature

Surface spreading tropical turf surface, still supported by root ABOVE LEFT: Rapidly spreading Long reach of the legumes vaginalis is a dedicated low growing via nitrogen fixation by symbiotic low-profile Alysicarpus vaginalis Willow leaved primrose weeds anchorages on adjacent turf. creeping herb while the others are rhizobia bacteria in the root nod- Tropical (warm season) grasses ABOVE: Diminutive Desmodium Mimosa pudica, Desmodium more versatile, evolving a low profile ules, although this will be of little (Ludwigia) is already in in the long grass Surface spreading weeds create in sports and amenity turf generally species and Alysicarpus vaginalis habit in frequently cut turf and consequence on fine turf that is big problems for turf and amenity possess much broader leaves and ABOVE RIGHT: Tridax procum- are leguminous weeds of tropical semi-erect woody stems in amenity regularly fertilized and sprayed the UK (inset above) whilst bens spreading from turf across managers with a wide range of form thicker swards than do cool a hard surface turf. All three are important matt grass. The delicate reddish purple with herbicide to maintain weed- carpet daisy is a problem creeping and matt-forming broad- temperate grasses like Festuca and ABOVE RIGHT (INSET): Willow forming weeds of sports turf and bean-like flowers of Desmodium free status. leaf herbaceous plants responding Agrostis. Growth rates are much leaved primrose (Ludwigia) is savannah (parkland) grass spread- and Alysicarpus borne on erect on turf near the seashore rapidly to high temperature, rainfall faster too but still no match for already in the UK ing rapidly to colonise large areas stalks can be confused but are All things to all habitats and humidity. The most effective dedicated matt forming turf weeds ABOVE FAR RIGHT: Carpet in no time at all. All three will then easily distinguished from the light daisy is a problem on turf near and successful are those with run- like Alysicarpus and Sida acuta the seashore spread out across adjacent hard purple/mauve pompom flowers of Sida acuta (Malvaceae) is called ning and creeping stems, above or (sweet broom). And opportunistic surface areas for a considerable Mimosa pudica. sweet broom but there is nothing BELOW LEFT: Fast spreading below ground, especially if they root turf weeds including Mimosa Mimosa pudica swamps wet turf distance to cover substantial areas The best way to separate them sweet about this plant as one of the at the nodes. pudica and Desmodium which rap- and amenity grass all supported by a root base now a is by the foliage. Alysicarpus bears most versatile amenity weeds of Many which spread by nodal idly colonise turf in the wet season BELOW: Mimosa pudica, Sida good distance away. simple rounded to boat-shaped the wet and humid tropics. Plants acuta and Desmodium have rooting, as their creeping stems forming large unsightly patches of overwhelmed this turf Each spreads through creeping leaves in alternate positions along develop rapidly into low-growing elongate, can spread a metre or weed growth in a remarkably short and ground hugging stems which the stem. Desmodium has com- herbs up to one metre high in open FAR RIGHT: Tropical turf grasses more across impenetrable hard space of time tend to have comparatively freely root at the nodes. Alysicarpus pound leaves comprising one pair waste places, or stay as a prostrate broad leaves of side leaflets and a terminal leaflet plants in grassland or closely mown each on a short stalk. Technically, turf, still producing the peach it is a compound pinnate structure coloured flowers on a daily basis. but at first glance looks like a three This bushy plant with woody leaflet compound palmate leaf. stems has short hard hairs making Mimosa has a compound pinnate it rough to touch and difficult structure with leaves pinnately control when fully grown. In the arranged into one or two pairs of prostrate biotypes infesting turf leaflets further subdivided into 10 the whole leaf takes on a reddish to 20 pairs of smaller leaflets. The hue. Flowers are delicate and peach leaflets are sensitive and close up coloured having a translucent when touched. basal area with orange coloured Mimosa pudica is viscously ‘veins’ (lines or creases) extending thorny and not the sort of weed up to the apex of the petal. welcomed on sports grounds and Despite its weed status sweet other public places like parks and broom does have some positive savannahs. On the other hand the points, apart from the beauti- soft leaves and stems of Alysicarpus ful flowers. The hard wiry stems (called Alyce clover by farmers in can be cut and tied in bundles to North America) provide highly make brooms for sweeping and nutritious animal fodder. the macerated stem and leaf tissue All three contribute to soil fertility are traditionally used as a poultice

48 GI DECEMBER 2011 DECEMBER 2011 GI 49 L&D Feature

to alleviate the pain and swelling invariably have to cope with weeds associated with sprains. that are both xerophytic (adapted to the dry conditions of sandy soils) Daisies everywhere and halophytic (adapted to high Unlock the potential salt concentrations). Classic in The most ubiquitous and ver- the Caribbean is Wedelia trilobata satile weeds of temperate amenity (carpet daisy) with creeping stems, habitats are plants from the family leaves shaped like duck’s feet and of greenkeepers Asteraceae (Compositae), including bright yellow daisy like flowers. dandelions, daisies, cat’s ear and The ‘rough’ as an area of unman- ragwort. The same situation occurs aged grass does not take on the in the tropics where two white same importance on tropical golf ‘daisy-like’ weeds are among the courses and for very good reason. most widespread and adaptable On temperate courses grass may weeds. typically reach a metre high during With its rough non-descript spring and summer and then die daisy-like flowers, Tridax procum- right back until the following spring. bens is one of the most frequently Not so in the tropics where grass occurring and fast spreading weeds grows throughout most of year with throughout the tropics. Biggest many species like elephant grass weed problems occur in the amenity reaching three metres with ease. It sector where it spreads quickly and is not so much the case of losing the efficiently rooting at the nodes into ball but of losing the golfer. soft ground and from there across adjacent hard surfaces. Flowers are Herbicides and environmental single heads 15mm wide with short integrity widely spaced cream coloured ray florets surrounding a round central Three factors make herbicide use core of densely packed yellow disc a difficult and tricky operation. First florets. Leaves are very hairy and is high rainfall so timing is critical. rough to touch and the flowers Second there is a tradition of grazing more resemblance to thistle heads animals on public amenity land. Last Become a than daisies, hence the common but not least, is the question of envi- ABOVE RIGHT: Large butterfly name of rabbit thistle. Two interest- ronmental integrity and preserving populations make herbicide use a tricky business. Euptoieta ing common names have evolved in biodiversity. UK Turf Managers are hegesia (brown biscuit butterfly) creole dialects of English speaking under increasing pressure to pro- shown here on Bidens pilosa, and ABOVE SECOND RIGHT on Caribbean islands like Trinidad tect and preserve wildlife including key sponsor Tridax procumbens with its strong historical French insects and especially butterflies. In influence. They are ‘mawgwit blan’ variety and density the UK butterfly Gold Key derived from ‘Marguerite Daisy’ population pales into insignificance Sponsors (white daisy) and ‘bouton blan’ compared with that in the Carib- The funding provided by Gold and Silver Key supporters means that BIGGA derived from ‘bouton blanc’ (white bean. The most notorious weeds can continue to produce training and career aids including DVDs, CD Roms, button). like Tridax procumbens and Bidens Like its temperate relatives pilosa are often the most attractive ﬁ eld-guides, as well as refunds for training fees, subsidised learning and Bidens pilosa crops up everywhere to butterflies. development courses, the lending library, careers advice, posters and manuals. through prolonged flowering periods, high seed set and efficient Wet weeds on the move means of fruit and seed dispersal. All opportunities and niches on Equatorial regions are inher- disturbed ground and cracks in ently wet and humid with weeds Thank you to our Gold and Silver Key Sponsors pavements or walls are exploited to adapting to suit. Waterways, lakes, the fullest extent. ponds, ditches and drains are Silver Key Each flower is a capitulum continually clogged up with weeds Sponsors consisting of 5 to 6 white petals and some are not as tropical as (ray florets) surrounding a dense you might think. The willow leaved cluster of yellow disc florets in the primrose (Ludwigia species), so centre. Bidens spilosa has a wide called because the leaves are willow range of common names including shaped and the yellow flowers Spanish Needle, Cobbler’s Pegs and resemble primroses, have been Farmer’s Friend. ‘Rabbit Meat’ is found on at least two sites in the the most commonly used name in United Kingdom – the New Forest Trinidad where its soft succulent in Hampshire and a wetland site in growth available year round is the City of London. traditionally used as rabbit feed. The weed is well established in France. Another nominally tropical Sand, sea and rough weed of damp wet places is not too far away. Eclipta prostrata (false This article comes to Sand in bunkers is one thing but daisy) is currently causing big you courtesy of the encroaching sand from the sea- weed problems in southern Europe BIGGA Learning and Development Fund. shore which many golf courses in having already invaded North

Thankyou to all our key the Caribbean are unavoidably near America reaching as far north as sponsors is another. As such greenkeepers New England.

50 GI DECEMBER 2011

SALTEX11_A2_POSTERS.indd 2 26/08/2011 15:56