NW I Issue 35 I 2013 noteworthy Small landholder series NW 51 I2014 Establishing effective windbreaks on the Strong winds can wreak havoc on • improve growth by Windbreak design crops, pastures, vineyards and reducing moisture stress To ensure a windbreak achieves orchards causing breakages, fruit • protect from wind damage the desired purpose, it needs to be fall and sandblasting. carefully designed. • provide shade and shelter for Small landholders can avoid livestock The following key factors should potential damage to their farming be considered: enterprise with careful planning. • lower the watertable in ‘boggy’ areas • orientation Before planting a windbreak you must consider it’s purpose, • increase biodiversity • tree spacing orientation, spacing, length, height • reduce wind evaporation from • height and length and the most suitable species for farm dams. • set back distance your property and the enterprise you are trying to protect. The benefits of correctly designed • choosing suitable species. windbreaks generally outweigh the Land owners situated on Western possible disadvantages. Orientation Australia’s Swan Coastal Plain Windbreaks should be at right are predominantly faced with The drawbacks of planting windbreaks are a perceived loss angles to the prevailing wind strong easterly winds on summer direction. For properties on the mornings, which swing around to of land as well as the money and the south-west in the afternoon. time taken to plant the trees and ongoing maintenance (pruning, Tagasaste used as part of During winter, damaging winds irrigation, fencing and fertilising). a windbreak for a cropping can prevail from the north-west. operation. The risk of damage can be greatly reduced by establishing windbreaks to provide protection. Windbreaks work by reducing wind speed and turbulence downwind of the break. They should be permeable and aim to filter the wind, not block it out completely. The most cost-effective windbreaks are trees, which can also offer many additional benefits to the property, including: • prevent soil erosion

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Swan Coastal Plain, a windbreak running north-north-west to south-south-east will give the best protection without causing excessive winter shade. It’s important when planning to be aware of access roads or other structures that may be impacted.

Tree spacing An effective windbreak will filter the wind, not stop it from passing through. Permeability should be about 50% with gaps minimised in the Planting at least three rows offers Mechanical planting can be windbreak to prevent wind tunnels, some insurance against gaps from more time effective. which may cause direct damage to seedling or mature plant deaths. plants on the other side. If a tree dies another should be The rows should be planted about planted in its place. Windbreaks work best when three to four metres apart. Most they consist of several rows of Shrubs are best planted on trees/shrubs should be planted in staggered trees and shrubs. This the outside (windward), with a line about three to five metres allows the trunks of one row to be taller trees on the inside of the apart (wider gap between trees, aligned with gaps in the next row. windbreak. lesser gap between shrubs). Table 1 Local species suitable for windbreaks. If planting only one or two-row windbreaks is unavoidable, Dry sand areas reduce the spacing between Trees/tall shrubs (>3m) Shrubs trees to achieve faster closure of the canopy and to insure against Peppermint Coojong gaps. (Agonis flexuosa) (Acacia saligna) Moonah/Rottnest tea tree Olive Where an access track or gate is (Melaleuca lanceolata) (Grevillia olivacea) needed, plant some shrubs right up to the gate/track to help prevent Woody Red eyed wattle the wind from accelerating through ( occidentale) (Acacia cyclops) the space. Spearwood One sided bottlebrush An additional short windbreak at (Kunzea glabrescens) (Calothamnus quadrifidus) least twice the length of the gap to Winter wet flats the windward side of the access gap can also help. Trees/tall shrubs (>3m) Shrubs Height and length Swamp peppermint Swamp blood flower The higher a windbreak the larger (Agonis littoralis) (Calothamnus lateralis) the area it will protect. Swamp sheoak Mountain kunzea However, height is best limited to (Casuarina obesa) (Kunzea recurva) 10m to prevent excessive shading Spearwood Grey honey myrtle of the adjacent area. (Kunzea ericifolia) (Melaleuca incana) Windbreaks offer wind protection Wonnich Robin redbreast bush to a distance of about 10 times (Callistachys lanceolata) (Melaleuca laterita) their height.

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For example, a 5m windbreak trees are planted to the north of will give protection for about 50m the cropping area to minimise downwind. shading in winter.

Protection is greatest at ground Choosing suitable species level so orchards, grapevines • selection of species with A wide range of species are and other taller crops will be less foliage close to ground level available for windbreaks (see protected because of their height. Table 1). • a combination of species to The length of the windbreak needs reduce gaps and provide Choose species that are well to be a minimum of 15-20 times biodiversity. adapted to the site conditions. the height of the trees; otherwise If suitable, deciduous trees can be wind will be deflected around the Plants which are native to the considered for frost-susceptible ends, reducing its effectiveness. area are highly specialised and locations to prevent cold air being generally have very few pests or Therefore a 5m high windbreak trapped by the windbreak. diseases. should be 75-100m long. It is important to check with a tree Choosing the wrong species for supplier if any of the potential Set back distance a soil type and rainfall area can species for use as a windbreak are To reduce shading and competition end in poor growth and premature a risk of becoming a weed. from tree roots, windbreaks should deaths. be planted at least 10m from When choosing species consider Establishing a windbreak any crop. the following: Nearly all soils benefit from ripping Allow a greater buffer area if tall as it breaks up compacted soils • the tree species matches the windbreak species are being used. such as those found on properties soil type with a long history of grazing. Sufficient room should be left to • mature height and lateral root allow ripping of the tree roots, It’s best to deep rip in late summer growth vehicle access and turning space. to early autumn when the soil is A greater distance between crop • water requirements and growth dry, and to a depth of 50-80cm. rate and windbreak is required when Mounding may be necessary in waterlogged areas. Mounds should be 20-30cm high by 1m wide and done on the contour.

Weed control Before the trees are planted, control weeds to a distance of 1m outside the proposed tree row/s by cultivation and/or with herbicides. A non-residual herbicide such as glyphosate can be used. For more effective weed control use a residual, pre-emergent herbicide such as simazine (only if no run-off can occur) and wait Figure 1 A windbreak consisting of trees and shrubs breaks the at least two weeks before planting force of the wind. Streams of air will pass through and over the the trees. top (Source: Primary Industries and Resources SA).

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Consider irrigation and consider using tree guards specific fertiliser to the pest/s if possible. If you use local species and plant During establishment of a early after the break of season, windbreak it is recommended to the trees should be able to get exclude stock, so trees can reach established before the dry, hot their maximum height without any For more information summer. setbacks. Noteworthy 1 - Safe chemical However, nearly all species will Temporary or permanent fencing spraying for small landholders benefit from being watered once a could be erected. Noteworthy 2 - Fencing for week during the first two to three beginners summers if possible. Consider allowing stock to access the shade offered by the Noteworthy 41 - Waterwise Irrigation is also likely to promote a windbreak once the understorey is irrigation - big benefits for sustained growth rate and reduce well developed, but remove them small properties root invasion into any irrigated if damage and gaps in the trees/ Nurseries production areas. shrubs become apparent. Rural suppliers Fertiliser requirements will depend Windbreaks can be a great on the species you choose, but addition to any property. Landcare groups most trees (including natives) will benefit and grow more quickly with They can help prevent soil some additional nutrients. erosion, protect plants from wind damage, provide shelter for Check with your tree supplier for livestock, increase biodiversity and recommendations. reduce evaporation from dams. Control pests, disease and However, it is vital you take the stock time to plan. Using local or native species will Consider purpose, location, design minimise pest and disease attack. and species, so you get it right Contact details Rabbits, kangaroos and ducks the first time and enjoy the many Small Landholder Information can find seedlings tasty, so try to benefits windbreaks can provide Service (SLIS) control pests before planting or your property. agric.wa.gov.au/small_landholder +61 (0) 8 9733 7777 or +61 (0) 8 9780 6100

Important disclaimer The Chief Executive Officer of the Department of Agriculture and Food and the State of accept no liability whatsoever by reason of negligence or otherwise arising from the use or release of this information or any part of it. © Western Australian Agriculture Authority 2014

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