Winter Pest and Disease Control with Lime Sulphur

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Winter is the traditional time to prune and spray deciduous fruit trees and vines. Spraying is carried out at this time to eliminate pests and diseases which can overwinter and emerge in spring.

Two separate treatments are usually employed in winter. Oil sprays are often used to control overwintering pest insects, and fungicides are used to treat the many fungal diseases which emerge during the warm, wet spring season.

Lime Sulphur serves both as a fungicide to control certain fungal diseases and also kills overwintering pest insect, a great convenience to gardeners.

 

What is lime sulphur?

Lime Sulphur is a reddish-yellow liquid with a distinctive rotten egg smell which is soluble in water. It is a mixture of various calcium polysulphides, and its use is accepted in organic gardening as it’s made by reacting together sulphur and builder’s lime (calcium hydroxide) – which is different to garden lime (calcium carbonate).

It’s quite alkaline, lime sulphur has a pH of 10.5-11.5, it’s considered caustic or corrosive, but to put it into perspective, it’s alkalinity is somewhere between milk of magnesia (pH 10.5) which is taken for indigestion and ammonia (pH 12). At around pH 11, it’s three pH points (10x10x10) or 1,000 times less alkaline than caustic soda with a pH of 14. Either way, avoid contact with skin and eyes, as you would with any garden chemicals.

Lime sulphur is quite an old invention and is possibly the earliest synthetic chemical used as a pesticide. It was originally developed by Grison, the head gardener at the vegetable houses in Versailles, France in 1851 to protect plants against mildews. As such, it was originally known as “Grison Liquid” or “Eau Grison”. The first use of lime sulphur for the control of peach leaf curl was in California in 1886.

 

How it works

Lime sulphur is an eradicant which acts by killing fungi on contact. It breaks down after it’s applied, releasing sulphur. The sulphur is the only part that’s toxic to fungi, and it eradicates them through direct contact or through fumigation by sulphur vapours, which can work from a distance.

To explain in simple terms how sulphur works with fungi, they absorb it and it interferes with their ability to create energy, it also turns into hydrogen sulphide (commonly known as “rotten egg gas”) which poisons them.

In more technical terms, sulphur has two modes of action, impaired electron transport and hydrogen sulphide (H2S) formation. Sulphur disrupts the transfer of electrons in the cytochrome system respiratory chain of fungi, depriving the cell of energy, and causing the reduction of sulphur to hydrogen sulphide (H2S), which is toxic to most cellular proteins, killing the cell.

Lime sulphur generally prevents plant disease by allowing sulphur to penetrate leaf tissues and kill germinated spores. It is toxic to insects and mites due to hydrogen sulphide formed through reaction of the polysulfide components of lime sulphur with water and carbon dioxide, or put more simply, lime sulphur reacts with the atmosphere to produce hydrogen sulphide (“rotten egg gas”) which poisons the pests.

 

Pests and diseases controlled with lime sulphur

Lime sulphur can be used to control a range of fungal diseases including Black Spot, Powdery Mildew, Freckle, Leaf Curl, Rust, Shot Hole and Brown Rot, as well as various Scale and Mite pests.

 

How to use lime sulphur

Lime sulphur is primarily used when plants are dormant but can also be used as a growing season spray.

Dormant season applications are applied late winter, after frosts have passed and before leaves are present.

Growing season applications can be made when leaves are present but should be applied early morning or late afternoon to avoid leaf burn.

To avoid plant damage caused by lime-sulphur, DO NOT spray when:

  • temperatures exceed 32°C
  • when soil is dry and plants are suffering from moisture stress.
  • when freezing weather is expected.
  • within 14 days of an oil spray.

When spraying, avoid contaminating waterways and fishponds, do not allow spray to drift onto aquatic environments. Keep children, pets, wildlife and birds off treated areas until the spray is dry.

Lime Sulphur can be used to controls a range of fungal diseases and pests on apples, pears, stone fruit, citrus, grapes, tomatoes, roses & ornamentals.

There is no withholding period, it’s a low toxicity product, so produce can be harvested as required.

It’s an ideal winter clean up spray – spray in winter for prebloom powdery mildew control on apples, leaf curl control on peaches and nectarines, and control of scale on stone fruit trees. Spray roses after pruning to control powdery mildew and mites.

 

When to spray

The best times to spray different crops as usually listed on the label, timing depends on the crop and the pest or disease. As a quick guide:

Stone Fruit such as almonds, apricots, nectarines, peaches, plums are sprayed while trees are dormant, prior to bud swell. It’s too late to spray once flowering occurs.

Pome Fruit such as apples are sprayed during dormancy to late bud swell.

With apples, there are a few precautions to be aware of. Lime sulphur used after late green tip will restrict growth and depress yield.

  • Do not use lime sulphur on Delicious or Cox’s Orange Pippin apples.
  • Lime Sulphur used after late green tip stage (period of bud movement when the buds show green tips from the emerging leaves) will restrict growth and depress yield.

Grape Vines are sprayed as near as possible to bud burst.

Roses and many other ornamentals can be sprayed during dormancy as a winter spray, or during the growing season from spring to autumn, make sure to wet the leaves and repeat as required.

Tomatoes and other vegetables can be sprayed during the growing season from spring to autumn, make sure to wet the leaves and repeat as required.

 

Sulphur sensitive plants

Some plants are sensitive to sulphur and should NOT be sprayed during the growing period when they are in leaf – these include apricots, raspberries, cucurbits, and peaches. Check if plants are sulphur sensitive before spraying during the growing period.

 

Lime sulphur or copper fungicides?

Lime sulphur is both an insecticide and a fungicide, whereas copper fungicides are just that. Another important consideration is that copper is toxic to plants when there’s a lot of it in the soil, and it doesn’t break down at all. Repeated seasonal spraying with copper-based fungicides aren’t the best for the soil. Never apply copper to strawberries, because severe phytotoxicity (plant toxicity) will result under almost any conditions. Use copper fungicides when the use of lime-sulphur is not advised (and the use of copper fungicide is!), and in those cases, use just enough spray to wet the plant surfaces without runoff.

As a handy tip,, some organic gardeners prevent runoff or spray drift by placing newspaper or plastic sheet under the tree being spayed with copper fungicide to prevent it getting into the soil.

 

 

References:

  1. Lime-sulfur: A fungicide used to control a variety of diseases by Don Janssen, Extension Educator, University of Nebraska–Lincoln, Nebraska Extension in Lancaster County – https://lancaster.unl.edu/hort/articles/2002/lime-sulfur.shtml
  2. https://www.agric.wa.gov.au/fruit/fruit-trees-and-vine-protection?page=0%2C1
  3. 2018 Crop Protection Guide for Tree Fruits in Washington, Fruit and Leaf Injury, Washington State University – http://www.tfrec.wsu.edu/pages/cpg/Leaf_Injury
  4. University of Maryland Extension, Home and Garden Information Center, Fruit – Fungicides – https://extension.umd.edu/hgic/fruit-fungicides
  5. Rural Industries Research and Development Corporation – Growing Organic Apples – World class production systems for new Australian apple varieties

 

 

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Choosing a Disposable Dust Mask Respirator for Air Pollution and Smoke Protection

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Disposable dust masks or respirators offer protection from fine particulate matter in the air such as dusts, aerosols and smoke.

At the time of writing, respiratory protection has been in high demand in Australia due to the extensive bushfires sweeping through the country and the degradation in air quality to hazardous levels.

According to news reports:

“The fires have burned 3.6 million hectares of land in NSW, 1.2 million hectares in Western Australia, at least 250,000 hectares in Queensland, and more than 91,000 hectares in South Australia, according to the states’ fire authorities. In total, more than 5.1 million hectares have been burned — an area the size of Costa Rica. To put it into perspective, California’s deadliest-ever fire burned about 62,053 hectares, and this year’s Amazon rainforest fires burned under a million hectares.”

The effect on air quality can be seen clearly below in one of Australia’s major cities quite some distance from the rural fires.

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Air quality index report in Melbourne, Australia on 14th January 2020 during bushfire crisis

 

Selecting a Respirator With the Correct Rating

It’s important to select the right respirator, as most common household dust masks won’t filter our smoke!

 

Australian/New Zealand Standards

For protection from particulates, there are three classes of filters under Australian/New Zealand AS/NZS1716 standard, and these are P1, P2 and P3.

P1 – used for mechanically generated particles such as silica, dusts, powders. Protects against low levels of dust, used for hand sanding, drilling, and cutting.

P2 – used for mechanically and thermally generated dusts such as welding fume, metal fume and smoke. Protects against moderate levels of dust, offer higher protection than P1, can be used for plastering and sanding.

P3 – used for all particulates requiring high protection factors. Protects against higher levels of dust, offers higher protection than P1, and P2, can be used for handling hazardous powders such as those in the pharmaceutical industry and chemical fumes.

 

US Standards

In the United States, respirator masks use a different rating code, such as N95 or N99.

N95 – Those respirators with a N95 rating can filter out up to 95% of the PM2.5 particulate matter from the air you breathe. The N95 rating is an efficiency rating from the National Institute for Occupational Health and Safety (NIOSH) that means the N95 mask filters out (95)% of (N)on-oil particles larger than 0.3 microns (0.3 micrometres = 0.0003mm).

N99 – A N99 rated respirator filters out 99% or more of non-oil-based particles. There are drawbacks with a more efficient filter though, they are much harder to breathe through, making your lungs work harder, which is noticeable during physical activity, and they can cost quite a bit more.

 

Using P2 and N95 Rated Masks for Smoke Protection

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Vented P2 rated respirator mask suitable for smoke protection, venting is optional

NOTE: For protection against smoke, only P2 or P3 (N95 and N99) rated masks are adequate, P1 masks will NOT work.

P2 rated masks are the preferred choice for protection against smoke particles in the air because they are a bit cheaper and easier to breathe through than P3 rated masks. A P2 rated mask/respirator is an AS/NZS1716 rated particle filter for use with mechanically and thermally generated particles (such as smoke), and are also the recommended type for use for infectious diseases. P2 filters are known to effectively capture particles in the sub micron range and are suitable for very small particulates such as bacteria or viruses (although these are normally associated into or onto larger droplets or aerosols, for example, when people sneeze). The USA’s equivalent rating for P2 respirators is N95.

A mask only works well if it fits well on your face, as any gaps between the mask and your skin will allow the pollutants to enter your nasal passage and cause health issues. Make sure any mask fits well and makes a good air seal, especially around the bridge of the nose. Facial hair, such as a beard, will prevent a good seal against the skin.

If masks are to be used while carrying out physical activity, such as working outdoors, or engaging in physical fitness activities such as running or cycling, then it is important to choose a vented mask that has a one-way exhalation valve to prevent moisture build-up within the mask which will clog the masks and make breathing in quite difficult.

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Vented respirator mask with one-way valve makes breathing easier and prevents moisture build-up

 

When P2 Masks Must Not Be Used

There are several applications where P2 filters should NOT be used:

  1. When the ambient Oxygen level is not guaranteed to be above 19.5%.
  2. For capture of gases or vapours.
  3. For persons with beards or other facial hair that interferes with the face seal

 

Measuring Air Quality Particulate Matter – What is PM2.5 and PM10 ?

One measure of air quality is the amount of extremely small solid particles and liquid droplets suspended in the air, which are referred to as particulate matter (abbreviated as PM). Particle pollution may reach extremely high levels during bushfires or dust storms, which can be hazardous to human health.

The size of particles determines their potential to cause health problems. The smaller they are, the more easily they can bypass the body’s defences and enter further into the body.

What damage can this fine particulate matter do to the body?

From a government source, the New South Wales Department of Health:

PM10 (particles with a diameter of 10 micrometres or less): these particles are small enough to pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects.

PM2.5 (particles with a diameter of 2.5 micrometres or less): these particles are so small they can get deep into the lungs and into the bloodstream. There is sufficient evidence that exposure to PM2.5 over long periods (years) can cause adverse health effects. Note that PM10 includes PM2.5.

 

To get an idea of how small these particles are, 10 micrometres = 0.01mm, and 2.5 micrometres = 0.0025mm

The air quality measures identify how many micrograms per cubic metre (µg/m3) of PM10 and PM2.5 particulates are present in the air.

Listed below are some of the PM (particulate matter) exposure limits set by various countries.

  • Australian limits: Daily average (24-hour) PM10 = 50 μg/m3, PM2.5 = 25 μg/m3
  • European Union limits: Daily average (24-hour) PM10 = 50 μg/m3
  • Hong Kong limits: Daily average (24-hour) PM10 = 100 μg/m3, PM2.5 = 75 μg/m3
  • United States limits: Daily average (24-hour) PM10 = 150 μg/m3, PM2.5 = 35 μg/m3

 

Air Quality Levels, What the Numbers Mean

There are two measures that are often used as an indicator of air quality:

  1. Actual Values – many devices which measure air quality, and some air filters which can display air quality values will report the micrograms per cubic metre (µg/m3) of PM2.5 particulates directly
  2. Index Values – government sites will report air quality as an index, such as the US EPA AQI (Air Quality Index), which is a calculated value based on the measure of micrograms per cubic metre (µg/m3) of PM2.5 particulates

 

The table below defines the Air Quality Index scale as defined by the US-EPA 2016 standard:

 

Air Quality Index

______ AQI value: 0 – 50
PM2.5 Concentration: 0-12 µg/m3
Air Pollution Level: Good
Air quality is considered satisfactory, and air pollution poses little or no risk
Cautionary Statement (for PM2.5): None

______ AQI value: 51 –100
PM2.5 Concentration: 12-35.5 µg/m3
Air Pollution Level: Moderate
Health Implications: Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
Cautionary Statement (for PM2.5): Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.

______ AQI value: 101-150
PM2.5 Concentration: 35.5-55.5 µg/m3
Air Pollution Level: Unhealthy for Sensitive Groups
Health Implications: Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Cautionary Statement (for PM2.5): Active children and adults, and people with respiratory disease, such as asthma, should limit prolonged outdoor exertion.

______ AQI value: 151-200
PM2.5 Concentration: 55.5-150.5 µg/m3
Air Pollution Level: Unhealthy
Health Implications: Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects
Cautionary Statement (for PM2.5): Active children and adults, and people with respiratory disease, such as asthma, should avoid prolonged outdoor exertion; everyone else, especially children, should limit prolonged outdoor exertion.

______ AQI value: 201-300
PM2.5 Concentration: 150.5-250.5 µg/m3
Air Pollution Level: Very Unhealthy
Health Implications: Health warnings of emergency conditions. The entire population is more likely to be affected.
Cautionary Statement (for PM2.5): Active children and adults, and people with respiratory disease, such as asthma, should avoid all outdoor exertion; everyone else, especially children, should limit outdoor exertion.

______ AQI value: 300+
PM2.5 Concentration: 250.5-350.5 µg/m3
Air Pollution Level: Hazardous
Health Implications: Health alert: everyone may experience more serious health effects
Cautionary Statement (for PM2.5): Everyone should avoid all outdoor exertion.

 

How Long Can You Use a Disposable Respirator?

Disposable respirators can be used more than once, in fact they can continue to be used as long as they still work.

A good rule of thumb for replacing your disposable respirators is to change them out when they are soiled, damaged, or if breathing becomes difficult.

Another important consideration is hygiene. To avoid germs, don’t share dust masks with others. There are recommendations to change disposable respirators out after 8-10 hours of use, even if they’re not dirty to prevent them becoming a home to germs.

 

Caring for Your Health – Actions to Take During High Air Pollution Levels

When air pollution levels become a health hazard:

  • Use a respirator if you must go outside.
  • Where possible, follow the advice of the government health authorities and stay indoors, close doors and windows.
  • Use an air purifier with a HEPA filter if you have one to clean the indoor air.
  • A draught stopper used at the bottom of the front and back door to keep the cold out also helps keep some of the smoke out too.
  • When driving, set the car’s air system to recirculate air inside the car to prevent polluted air entering in the cabin.
  • Reduce physical exertion as this increases the amount of air through the lungs and the level of pollutants.

 

 

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Gardening Calendar (Australian Temperate Climate) – January

It’s January, and we find ourselves right in the middle of the summer season. It’s in this month and the next that we experience the hottest day-time and night-time temperatures of the year. With the weather so hot and dry at this time, and with hot north winds blowing, it’s important to keep up with the watering, especially for plants in containers.

The occasional heavy rains raise the humidity, and the warmth brings insects, so keep a lookout for any diseases or pests in the garden.

Cover peaches and nectarines with bird-netting to protect the fruit, and if you choose to thin out fruit on apples and pears now is the time to do it. Plum trees can bear very heavily and the brittle branches can break under the weight of the fruit, so it’s best to tie branches to supports or prop them up if they look too heavy.

Not forgetting the vegetables, it’s now time to harvest early potatoes, garlic, shallots and globe artichokes.

Sow some winter brassicas such as broccoli, brussels sprouts, cauliflower and swedes at this month, so they can be harvested in the winter season. To ensure that indeterminate (tall growing/staking variety) tomatoes ripen their fruit this late in the season, pinch out the growing tips to stop further green growth and remove any side-shoots, so the plant’s vigour is directed towards the fruit.

 

Things to Do This Month:

  • Continue tying growing vines and brambleberries such as blackberries and their hybrids back to supports or wires.
  • Prune summer fruiting raspberries – after fruit is picked, cut out old canes and tie new canes (that have grown this year) to supports.
  • Propagation of semi-hardwood (semi-ripe) cuttings is done in mid-late summer, use rooting hormone, and plant in moist commercial propagation mix, or make your own with one part coarse propagating sand (washed river sand) and one part peat or coconut coir.
  • Cut and dry herbs for winter use.
  • Harvest seed from perennial plants
  • Lest chance to sow vegetable seeds for harvesting in autumn.
  • Keep an eye on water gardens and ponds, water levels can get low due to evaporation. Aquatic plants, including oxygenators, can become overgrown and require thinning at this time of year.

 

Vegetables and Herbs to Sow:

Sow in January Harvest (weeks)
Amaranth ds 7-8
Asparagus Pea d 8-11
Beetroot ds 7-10
Burdock d 17-18
Carrot d 12-18
Chives ds 7-11
Climbing beans d 9-11
Cucumber d 8-10
Dwarf beans d 7-10
Kohlrabi d 7-10
Lettuce ds 8-12
Marrow d 12-17
Mustard greens d 5-8
Oregano s 6-8
Parsley ds 9-19
Radish d 5-7
Rosella s 21-25
Salsify d 14-21
Silverbeet ds 7-12
Sunflower ds 10-11
Swedes d 10-14
Sweet corn ds 11-14
Turnip d 6-9
Zucchini ds 6-9

Key:
d = sow directly into ground
s = sow in seed tray
ds = sow directly into ground or seed tray
*= frost tender
**= sow after frost

Download printable PDF version of Gardening Calendar (Australian Temperate Climate) – January

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Permaculture Plants – Australian Indigo, the Nitrogen Fixing Tree for Small Sites, an Alternative to Tagasaste for Urban Gardens

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In permaculture, tagasaste (tree lucerne) is used as a nitrogen-fixing tree on large sites and rural properties, but it can grow around 5-7m tall and equally wide, which is way too large for smaller urban properties. Luckily for Australian permaculture gardeners, we have a much smaller nitrogen-fixing tree available which works much better in small-scale gardens.

Indigofera australis, also known as Australian Indigo or Austral Indigo, is an attractive ornamental native Australian evergreen shrub varying in size and  habit, growing 1-2m tall and equally wide, more typically closer to 2m tall and wide in size. It’s also from the Fabaceae (legume) family, just like tagasaste, and is a nitrogen-fixing plant, which can be used to increase soil fertility, and as a nurse crop tree to protect growing young trees.

The delicate looking pinnate blue-green foliage can be lightly pruned to create a showy specimen or feature plant in a garden. During spring, bright pink to purple flowers are produced in long spires, which are a good nectar source and attract bees, butterflies, nectar-eating birds and other beneficial insects.

The leaves and stems can be used for making natural dyes, giving a range of colours from soft yellows through to light blues, depending on the plant growing conditions and the dyeing technique used.

The indigenous people of Australia used the crushed leaves of Indigofera australis to throw into the water to kill or stun fish and eels, and also placed roots which were hammered in salt or fresh water to poison fish.

This shrub can be used as a low windbreak, and it will tolerate extended wet periods and saline soils.

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The pink-mauve pea-like flower of Australian indigo is attractive to bees, butterflies and nectar-eating birds

This Australian native shrub is fairly hardy, being reasonably drought tolerant and able to handle light to moderate frosts. It will grow in full sun or light shade in most soil types, ranging from sandy soil to clay loam. It is adaptable to a wide range of climates, from sub-tropical, through to temperate and cool and even semi-arid. It’s best pruned lightly, don’t cut into old wood as it won’t regrow. It can be propagated from seed, division or by taking semi-hardwood cuttings.

Indigofera australis is capable of regenerating after fire, which breaks the dormancy of seeds in the soil, but it can also regrow by suckering from the roots that stay alive below the ground.

It’s easy to grow, and can be grown amongst fruit trees without any problem., I have mine growing in a food forest garden between two young dwarf citrus trees and an apple tree, in a full-sun location, and it flowers prolifically, attracting lots of bees. It’s not phosphorus sensitive like some Australian native plants (such as those from the Proteaceae family) so it doesn’t need any special care or native fertiliser formulations.

 

Propagation

Propagation of Indigofera australis is done from seed, but the seeds have a thick seed coat and seed treatment is required to break the physical dormancy.

Two methods of seeds treatment are described as follows:

  1. Scarifying – the seeds can be scarified by contact with an abrasive surface, such as fine sandpaper.
  2. Hot water treatment – this involves dropping the seeds into a container, filling it with boiling water, then and allowing the seeds to soak in the water overnight as it cools. Seeds that swell larger than their original size can be sown, while seeds which stay floating can be discarded as they’re usually infertile.

After sowing the seeds, germination should take around 3-4 weeks. The season to sow seeds is in late winter to early spring.

Indigofera australis can also be propagated from cuttings, and being evergreen would be propagated using softwood cuttings in early spring.

 

 

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Permaculture Plants – Tagasaste, the Nitrogen Fixing Tree for Large Sites

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Photo credits for all images in this article – Narelle Dandy, https://simplyorganicmag.com.au/

 

Permaculture is all about energy-efficient design, and if you can add a single design element to a site that can perform many functions, then that’s an incredible gain in efficiency!

A tree that could do almost everything would be incredible, but it doesn’t exist. The next best thing would be a tree that does a whole lot of useful things, and everyone who’s ever studied permaculture has probably heard about tagasaste or tree lucerne at some point or other.

How useful is tagasaste? To better understand a design element in permaculture, we perform a functional analysis by making a list of it’s inputs and outputs, its functions and properties.

 

A tagasaste tree can be used as:

  • A nitrogen-fixing tree, which can capture nitrogen from the air to improve soil fertility.
  • A productive source of high quality, palatable and non-toxic fodder and seed for livestock and poultry, with a high 20-24% crude protein content of its leaves.
  • A fast growing windbreak growing up to 7m, which can be hedged.
  • A nurse crop tree to protect young or frost sensitive trees.
  • A bee forage tree which produces prolific blooms of creamy white flowers in spring on previous year’s growth, producing a honey that is white in colour and mild flavoured.
  • A source of timber and firewood, the tree produces a useful dense wood and can be coppiced easily. Tagasaste doesn’t grow in a form suitable for milling, so it can’t be used to make timber planks or beams, but is suitable for making small items.
  • A source of material for pulp and paper making.
  • A feature tree in landscaping. Tagasaste is an attractive evergreen tree with a gracefully weeping habit and masses of white flowers.

 

Adding to its usefulness is that fact that it’s hardy and drought-tolerant, able to grow in areas of low rainfall, as low as 350mm per year, and survive winters as cold as -9°C.

This highly versatile tree often used as a case study in permaculture classes, because it has so many uses on large properties and farm, and brilliantly illustrates the design principle of ‘Each Element Performs Many Functions’.

 

Description

Tagasaste, also know as Tree Lucerne (Chamaecytisus palmensis syn. proliferus) is a drought tolerant evergreen tree from the Fabaceae (legume) family, originating from the Canary Islands. It’s grown extensively as a fodder tree to feed livestock on farms and used for land rehabilitation. Being a legume, tagasaste roots have nodules which house nitrogen-fixing Rhizobium soil bacteria, which live in a symbiotic relationship with the plant. The bacteria can capture nitrogen from the air and convert it into soil nitrogen which plants can utilise, and in exchange the plant provides sugars for them which they produces by photosynthesis.

In terms of size, Tagasaste trees grow quite large and are really only suitable for larger properties and farms. The unreliable internet sources which just cut-and–paste each other’s uncited information claim a height 3-4m high, which is inaccurate. If we look at reliable authoritative sources such as government agriculture extensions, scientific research, primary industry organisations and botany information centres, we find that Tagasaste grows closer to 5-7m (16-23’) high, with a canopy that is equally wide. The confusion probably stems from the fact that Tagasaste can have a variable habit, they don’t all grow to the same shape, some may be erect in habit or while other may have a more prostrate form.

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Tagasaste tree growing in the background covering the side of the house

 

The branches of this tree are long, leafy and pendulous, hanging down towards the ground.

Leaves are trifoliate, they’re a compound leaf divided into three leaflets. Each leaf is up to 7 cm in length and the undersides of the leaves are pubescent (softly hairy), just like the younger branches and flower sepals (the green petals at the base of the flower collectively known as the calyx which envelop the flower bud). The leaves are described as being dull green, bluish-green or grey-green in colour,

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Tagasaste leaves are trifoliate, consisting of three leaflets

 

Tagasaste produce scented, creamy white pea-like flowers in spring, but sometimes as early as winter, providing a source of forage for bees when other sources are scarce. The pollinated flowers produce flattened, black-coloured seed pods which are around 5 cm long. The pods contain 10 small, flat, oval shaped, glossy black seeds, 5mm long x 3mm wide x 1mm thick.

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Tagasaste seeds pods, showing glossy black seeds

 

tagasaste_1-1-2Close-up of Tagasaste seeds pods, which can disperse the seeds short distances by explosively releasing when mature.

 

Tagasaste Growing Requirements

Tagasaste is adaptable to a wide range of climates, growing in the tropical highlands and subtropics as well as in temperate regions with wet winters and dry summers.  It thrives in semi-arid areas with 350-1600 mm of annual rainfall, but can survive with as little as 200 mm of rain a year. With cold, It’s moderately frost tolerant when established, surviving frosts down to -6°C (with reports as low as -9°C). Young seedlings are frost tender and should only be planted out when all risk of frosts has passed.

This tree can be grown on a wide range of soils types (gravels, loams, acid laterites and limestones), but prefers sandy, gravelly deep and well drained soils. Good drainage is essential where rainfall is heavy, as tagasaste is very sensitive to waterlogging and wet heavy soils, even short periods of waterlogging can lead to infection by the fungal root disease Fusarium oxycarpum. Plant the tree in raised beds or on slopes and hillsides in areas where waterlogging may occur. Tagasaste are also not tolerant of saline soils.

Even though tagasaste prefer acidic soils (with a pH ranging from 4.8 to 6.5), they can cope with moderately acid to neutral soils (with a pH of 5.0 to 7.0), and survive in alkaline soils with pH 8.5, but alkaline and saline soils reduce their growth.

 

Environmental Impact of Tagasaste

What happens to the surrounding environment when Tagasaste is planted? Is it beneficial or harmful?

Let’s look at the matter objectively using information from reliable scientific sources and draw our conclusions from there!

When conducting research of published literature on the topic, it’s common to find different government department and organisations providing conflicting information, sometimes quite biased and unscientific. Certain government departments with a ‘weed-ist’ agenda claim Tagasaste to be a ‘weed’, an undesirable plant, but from my findings which I’ll detail below, the rationale doesn’t hold up when compared to the research-backed information from other government and research organisations with an agricultural focus, or against a basic foundational knowledge of ecology…

 

Improvement of soil fertility

Tagasaste is a nitrogen-fixing legume which will improves the nitrogen levels in the soil, acting as a pioneer species, creating more favourable conditions for the growth of other plant and tree species. It’s important to note that nitrogen-fixing (capturing atmospheric nitrogen from the air and converting it to a form usable by plants) can only happen if nitrogen-fixing bacteria are already present in the soil, as they reside in the tree’s root nodules.

The tree’s extensive root system which runs up to 10m deep is capable of tapping into water and nutrients very deep in the soil and bringing nutrients to the soil surface, making them available to shallower rooting plants as a mulch below the canopy.

According to one Australian government website – “Its nitrogen-fixing ability also increases soil fertility, helping other weeds to colonise invaded sites and out-compete the native species.”

Increasing soil fertility is a problem? Australian native wattles (Acacia species) also perform exactly the same ecological role as nitrogen-fixing pioneer trees, they’re from the same Fabaceae family as Tagasaste, and they play a pivotal role in the process of ecological forest succession, the creation and regeneration of forests. In fact, many Australian native plants, from tall trees to low groundcover plants are nitrogen-fixing leguminous plants! Also all plants require nitrogen to produce vegetative growth. This claim that nitrogen-fixing plants are problematic in Australian soils lacks scientific credibility in my opinion.

 

Soil conservation and reclamation

Tagasaste is used for revegetation of eroded areas, it’s planted as an easy to establish and fast-growing windbreak, to reduce wind erosion of the topsoil. The deep, extensive root system also helps bind the soil on steep slopes, reducing the impact of water runoff.

It’s been used to reclaim severely damaged ground, successfully growing in mining dumps and slag heaps. In New Zealand, tagasaste has been grown on gold dredge tailings.

Even though the tree is sensitive to saline soils, tagasaste has been assessed for salinity control In Western Australia, it’s been used to reduce water runoff and seepage, helping offset the rising water table effect which bring salts up to the soil surface.

Once again, according to another Australian government website, “In south-western Western Australia it grows in disturbed natural vegetation on lateritic soils in higher rainfall areas it is a serious invader of disturbed bushland. In all regions where it is found, it readily invades roadsides, creek banks and other disturbed sites and spreads from these areas into native bushland and grasslands.”

The claim is that tagasaste is a weed because it invades disturbed ground. The key word here is disturbed, and this is where the problem lies. Anybody who has studied ecology is familiar with the natural process of ecological forest progression. It’s a well-known fact that if any stable ecosystem is disturbed, either by natural or man-made factors, a small cycle of ecological progression, similar to the one which created the whole ecosystem, will occur. When this cycle happens, tough, short-lived annual plants (labelled weeds) will be carried in by the wind to stabilise the disturbance and prevent soil erosion and soil loss. Eventually short-live pioneer trees, often nitrogen-fixers, such as wattles, tagasastes and others will move in to shade the annual pioneer plants out and create a microclimate suitable for the climax canopy trees which will take their place. This is either wilful ignorance or intellectual dishonesty. The problem is not Nature’s reaction to disturbed ground, but the cause of the disturbance to a stable ecosystem which can resist ‘weeds’ naturally. What caused the disturbance??? Logging, overgrazing, irresponsible farming practices, overzealous bushland regeneration groups pulling up ‘weeds’ and removing trees but not replacing them with something else?

 

Self seeding pioneer plants, or human disturbance, which is the problem?

To directly quote another website claiming an alleged problem “Tree lucerne (Chamaecytisus palmensis) accumulates large quantities of long-lived seeds in the soil seed bank and readily germinates after fire or other disturbance, forming dense infestations that can smother native vegetation and prevent regeneration. Its nitrogen-fixing ability also increases soil fertility, helping other weeds to colonise invaded sites and out-compete the native species.”

If tagasaste was able to self-seed into stable ecosystems, the Australian government agricultural extension agencies wouldn’t need to advise farmers of seed treatment methods to improve tagasaste seed germination! To directly quote an agricultural fact sheet:

“The hard coat of tagasaste seed results in a very low germination of untreated seed. This can be overcome in two ways.Scarifying. Seed can be scarified by contact with an abrasive surface. … Hot water treatment.This involves dropping the seed into boiling water then immediately removing the container from the heat source and allowing the seed to soak in the water as it cools. Successfully treated seed swells and can be sieved off, and the unswollen seed treated again. New Zealand experience indicates that the swollen seed can be re-dried for mechanical planting, retaining its improved germinability”.

Once again, the keyword is disturbed soil! Anything and everything will pop up in disturbed soil as a natural restorative action to protect the soil.The fact that pioneer plants will arise after forest fires is expected, otherwise the soil will all erode away, and no forest would regrow. There’s more to Australian forests than monocultures of eucalypts regrowing from lignotubers after fires. Many plant and tree species exhibit this function. Nature’s wisdom seem to be interpreted as humanity’s problem, because human know how things ‘should be’, what would Nature know about sustaining and perpetuating life anyway…

The claim that tagasaste can form “dense infestations that can smother native vegetation” is bogus. Weed control is a concern for farmers trying to grow tagasaste. Research has shown that young tagasaste seedlings are impaired by competition from other plants. To quote an Australian government website for farmers, “Although tagasaste transplants grow rapidly, weed competition can be a problem, particularly with annuals such as Wimmera ryegrass and capeweed.Again there is little research information regarding weed control in tagasaste. Good seedbed preparation before planting or sowing can often be a help in weed control.”

A more honest assessment can be read on the website – Weeds of the Blue Mountains, under the title of ‘Impact on bushland’: “Tree Lucerne tends to stay at the edges of bush, but because it produces so many seeds, it has the potential to invade and modify native bushland.”

The survival of young tagasaste trees is reduced by grazing animals which find them quite palatable, and mature trees also face challenges to their longevity. It has been reported that where the bark from tagasaste has been stripped off by browsing sheep, it’s been observed that many of the trees died of Phytophthora fungus. Tagasaste have very few pest problems,  but they are susceptible to the tree lucerne moth  (Uresiphita ornithopteralis) and emerging seedlings are eaten by cutworms, grasshoppers and slugs.

On discussing the ability of tagasaste to spread, the Tropical Forages website, a collaborative effort between CSIRO Sustainable Ecosystems, Department of Primary Industries & Fisheries (Qld), Centro Internacional de Agricultura Tropical (CIAT) and the International Livestock Research Institute (ILRI) states that it “Spreads by seeds from the dehiscent pods.  However, hard seeds may not germinate in the soil for several years, and susceptibility of young seedlings to grazing limits its survival to protected or fenced areas.” When discussing weed potential, they state, “A fast growing species used for fodder and is invasive in a wide rage of landscapes.  It has naturalised in almost all areas where it has been planted, along roadsides or in adjacent bushland.  On lateritic soils in higher rainfall areas it is a serious invader of disturbed bushland.”

It’s an ecological fact that pioneer plants are designed to spread through disturbed ecosystems as part of a natural process to restore stability and protect the soil, which takes hundreds of years to form naturally. Unfortunately humans have a habit of disturbing stable ecosystems, throwing them out of balance, and then blaming the pioneer plants which are the symptom of the disturbance, not the cause, which is usually anthropogenic.

Common sense should dictate that when living near natural environments, responsible plant selection should be exercised, and all efforts should be made to minimise disturbance to the native flora and fauna which are in a delicate balance in any stable ecosystem.

 

Use as firebreaks

The dubious claims that tagasaste trees are a ‘weed’ because their seeds might germinate in large numbers after fires doesn’t stand up to scrutiny, its contradicted by the fact that tagasaste are used in Western Australia as a firebreak to protect pine plantations. The tagasaste trees, if planted densely enough to act as an effective firebreak, can not only prevents the spread of forest fires, and the loss of forests, but they also prevent the germination of their own dormant sees in the soil!

 

Saving our bees!

Tagasaste provide high quality pollen and nectar, and although spring flowering, can start flowering during winter, increasing the source of nectar for bees. According to Australian Geographic, Australia has more than 5,000 native bee species, and studies suggest that the main impacts of the controversial neonicotinoid insecticides are on wild bees rather than domestic honey bees in hives. They state that “the combination of wide scale use of multiple agrochemicals, loss of plant and habitat diversity, and climate change is a significant threat to both wild and domesticated bees.”

More bee forage on rural properties to support both wild and domesticated bee populations is a necessity, and bees don’t care where the plants originated from. With more bees, there’s increased pollination of edible crops, a huge benefit for farmers and food growers.

 

Using Tagasaste in Permaculture Designs

Tagasaste trees have quite an impressive list of uses, but that doesn’t mean they should automatically be included in any and every permaculture site plan. With good permaculture design, once we have performed a functional analysis of a design element, we need to critically assess whether the element is suitable for the site being designed, and what relationships we can establish with existing and new design elements on the site, and not just include it on the whim because other people are using it on their permaculture properties! There needs to be good design rationale for including any element in a design.

Tagasaste are excellent trees for large properties, especially on rural sites where grazing livestock are kept, but they’re less than ideal for small properties, especially urban sites.

There are better nitrogen-fixing trees for small-scale gardens, and if you want to use an Australian native alternative, then you may be interested in Austral Indigo!

 

 

References:

  1. Heuzé V., Thiollet H., Tran G., Hassoun P., Bastianelli D., Lebas F., 2017. Tagasaste (Cytisus proliferus). Feedipedia, a programme by INRA, CIRAD, AFZ and FAO. https://www.feedipedia.org/node/310, Last updated on February 28, 2017, 19:04
  2. New South Wales Department of Agriculture – Tagasaste (tree lucerne) Agfact P2.1.7, first edition 1986 Paul Dann, Research Agronomist Division of Plant Industries, Canberra Barry Trimmer, Livestock Officer (Sheep and Wool) Division of Animal Production, Orange (Reviewed May 2003, Brendan George) – http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0005/147272/tagasaste.pdf
  3. Eastham, J.; Scott, P. R.; Steckis,R. A., 1993. Evaluation of Eucalyptus Camaldulensis (river gum) and Chamaecytisus Proliferu (Tagasaste) for salinity control by agroforestry. Land Degrad. Dev., 4 (3): 113-122, http://dx.doi.org/10.1002/ldr.3400040302
  4. O’Donoghue, B., 2011. Tastee Tagasaste. Victoria Park Alpaca Stud, Alternative fodder, http://victoriaparkalpacastud.com.au/en/Tagasaste_Articles
  5. Nectar and Pollen Sources of New Zealand by R.S. Walsh, first published in 1967 and second edition in 1978 edited by Trevor Walton with assistance from David Williams, Rotorua.
  6. PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. http://plantnet.rbgsyd.nsw.gov.au
  7. VicFlora, Flora of Victoria website, sponsored by Royal Botanic Gardens Foundation Victoria, source: Jeanes, J.A. (1996). Fabaceae. In: Walsh, N.G.; Entwisle, T.J. (eds), Flora of Victoria Vol. 3, Dicotyledons Winteraceae to Myrtaceae. Inkata Press, Melbourne.
  8. Food and Agriculture Organization of the United Nations (FAO) – http://www.fao.org/ag/AGA/AGAP/FRG/Visit/Ida/Chamaecytisus%20palmensis.htm
  9. F. López, A. Alfaro, M.M. García, M.J. Díaz, A.M. Calero, J. Ariza, Pulp and Paper from Tagasaste (Chamaecytisus Proliferus L.F. SSP. Palmensis),
    Chemical Engineering Research and Design, Volume 82, Issue 8, 2004, Pages 1029-1036, ISSN 0263-8762, https://doi.org/10.1205/0263876041580730.

 

 

 

 

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Gardening Calendar (Australian Temperate Climate) – December

December is the first month of summer, and with the warmer weather gardens explode into life – lush, abundant and awesome to behold. With the days getting longer as we progress towards the longest day of the year, the summer solstice, there’s more time to enjoy the garden and the great outdoors!

During this time, temperatures can reach extremes as the days heat up, and gardens can get quite dry, so keeping up with the watering is important. Pests will also emerge with the warmer weather so keep an eye out for them!

‘Chop & Drop’ any broad beans or peas after harvesting, ‘chop’ the tops at ground level, and ‘drop’ on top of the soil as mulch, leave the roots in the ground to return any nitrogen in the root nodules to the soil.

As strange as it may seem, early summer is the time to sow some winter brassicas such as broccoli, brussels sprouts, cauliflower and swedes, so they can be harvested in winter.

Things to Do This Month:

  • Top up or add extra mulch around fruit trees and plants to retain moisture in the soil and prevent water loss from evaporation (keep mulch away from plant stems and trunks as this can cause stem rot/collar rot).
  • Propagate climbers by layering and propagate strawberries by pegging down runners onto soil.
  • Propagate plants by taking softwood (green) cuttings from now till January (after which they begin to harden off).
  • Last chance to plant potted fruit trees and vines to beat the summer heat (having roots, can be planted anytime, but best in spring & autumn). Make sure you pick a day when the weather is mild!
  • Continue tying growing vines and brambleberries such as blackberries and their hybrids back to supports or wires.Thin out fruit on plum trees if there is a risk of branches breaking.
  • Last chance to plant tomatoes and capsicum seedlings.
  • If you need to add new fish to ponds or water gardens, this is an ideal time as they acclimatise easier in the warmer weather.

Vegetables and Herbs to Sow:

Sow in December Harvest (weeks)
Amaranth ds 7-8
Angelica ds 18 months
Asparagus d 2-3 years
Asparagus Pea d 8-11
Beetroot ds 7-10
Borage ds 8-10
Burdock d 17-18
Cape Gooseberry ds 14-16
Carrot d 12-18
Chilli s 9-11
Chives ds 7-11
Choko d 17
Climbing beans d 9-11
Cucumber d 8-10
Dwarf beans d 7-10
French tarragon d 30-40 days
Kohlrabi d 7-10
Lettuce ds 8-12
Mustard greens d 5-8
Oregano s 6-8
Parsley ds 9-19
Pumpkin ds 15-20
Radish d 5-7
Rosella s 21-25
Rosemary d 12 months
Sage d 18 months
Silverbeet ds 7-12
Sunflower ds 10-11
Sweet corn ds 11-14
Turnip d 6-9

Key:
d = sow directly into ground
s = sow in seed tray
ds = sow directly into ground or seed tray
*= frost tender
**= sow after frost

Download printable PDF version of Gardening Calendar (Australian Temperate Climate) – December

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What is Integrated Pest Management (IPM)

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The problem of garden pest control is as old as agriculture itself, which started when humanity first cultivated plants for food more than ten thousand years ago.

Modern conventional pest control methods often use chemical controls as the first option, and usually ignore the real causes of pest problems. They rely on routine, scheduled pesticide applications. Spray this chemical at this time of the year, then rotate to a different chemical because pests develop resistance to chemicals…

There are far more strategic, intelligent and cost-effective ways to manage pests than wholesale chemical warfare without regard for the long-term consequences. The most common-sense scientific way to manage pests is by taking an ecological approach to the problem, since we are ultimately dealing with ecosystems filled with living organisms in complex relationships to each other.

Consider the fact that plants have been growing successfully on the planet for 460 million years before humans ever existed, despite the existence of pests – what does this tell us? Nature does have effective means of controlling pests and regulating pest populations, so there’s no need to reinvent the wheel.

 

Problems with Chemical Pest Controls

Are there any good reasons why home gardeners, gardening professionals and farmers shouldn’t use modern synthetic chemical pest controls? The main reasons are as follows:

  1. Chemical pest controls provide a temporary fix at best, and are ineffective over the long term.
  2. Chemical use disrupts the ecological balance. Predator insect species which eat pests and naturally control their numbers are more sensitive to pesticides. It has been consistently observed that after chemical pesticide use, there is a loss of predator species, and an explosion of pest population numbers.
  3. Pests naturally develop resistance to chemical pesticides as an evolutionary survival mechanism, so there’s a need to rotate pest control chemicals.
  4. Environmental toxicity is an undesirable consequence of pesticide use. Chemical persistence in the soil, bioaccumulation in living organisms, soil mobility and contamination of waterways and groundwater are known issues with chemical use. Local applications of chemical pesticides may move to off-site locations, contaminating food crops and harming non-target species.
  5. Toxicity to non-target species, including people, pets and wildlife.
  6. Social acceptance – increased awareness and public concern about chemicals.
  7. And the big one… Cost $$$ – which is ongoing! In 2016, the agrochemical market worldwide was worth 215.2 billion US dollars, and expected to increase to 308.9 billion US dollars in 2025!

It’s been said that necessity is the mother of invention, and to address the abovementioned issues, a far smarter approach to pest control has been developed, known as integrated pest management, abbreviated as IPM.

 

What Is Integrated Pest Management (IPM)?

IPM is a systematic, scientific pest management strategy based on prevention, monitoring, and control, that uses a combination of techniques to limit pest populations and the damage they cause to economically acceptable levels, while eliminating or drastically reducing the use of pesticides to minimise risks to people and the environment.

How Does IPM Work?

There are three key components to IPM strategy:

  • Prevention
  • Monitoring
  • Controls

Let’s examine each in turn.

 

Prevention

The goal of IPM is the long-term prevention of pests or their damage by managing the ecosystem.

IPM adopts a proactive approach – by understanding the environmental factors that affect the pest and its ability to thrive, we can create conditions that are unfavourable for the pest. This is the complete opposite of reactive nature of conventional chemical pest control, which is predicated on eliminating visible pests right now.

 

Monitoring

There are three parts to this IPM strategy, which are carried out as a series of consecutive steps in the following order:

  1. Monitoring – assessing the nature and scale of the problem by checking to identify pest types, pest numbers or pest damage.
  2. Correct pest identification – to determine whether the pest is a problem, and what the best management strategy is.
  3. Deciding to take action – After considering the pest biology and environmental factors, we can then decide if the pest be tolerated, or if the problem needs controlling, and if so, which management methods are the most effective.

 

Controls

Integrated Pest Management is integrated because it combines various pest management control methods together for greater effectiveness.

It’s only logical that if a certain pest control method is, for example, 60% effective, and another is 30% effective, then combining the two would increase the overall effectiveness of the pest control measures.

There are four categories of pest controls employed in IPM:

  • Biological controls
  • Cultural controls
  • Mechanical and physical controls
  • Chemical controls

Various types of controls (i.e. biological and cultural controls), or methods from within those controls (i.e. several different mechanical/physical controls), can be deployed together, and they can be escalated in terms of risk if required.

 

IPM Strategy, Escalation and Integrated Solutions

The pest control strategy of modern agriculture is to utilise the most toxic chemicals as the first option. That’s not very strategic because if pests become resistant, that leaves no escalation options available. In IPM, we would begin with the least toxic chemical control (or a non-chemical control) that would get the job done, leaving the most toxic chemicals as a last resort instead!

What happens when modern agriculture uses restricted chemicals so toxic that they’re not legally available to the general public for pest control? The contamination of food and water with pesticide residues is well documented, as is their impact on the environmental ecosystems which keep us alive. Paying such a heavy price for the temporary and short-term control of pests is a perfect example of a Pyrrhic victory, where the losses negates any real sense of achievement, in other words, an empty victory, which isn’t very strategic at all.

 

IPM is a scientific, evidence-based approach to pest control, which is based on the following principles.

  1. Strategy  – using a systematic calculated escalation strategy is a more efficient and cost effective way to control pests. The least harmful controls (chemical or other) are employed first, and usually combined to increase effectiveness. If these controls prove to be ineffective, then a step-wise escalation can be employed, using controls with slightly more environmental impact to get the job done. This leaves the control methods with the most environmental impact as a last resort option only.
  2. Prevention, monitoring, and control – pest control solutions are developed based on pest biology and behaviour.The science exists to describe and understand pest life cycles, habits and preferences, and we can use this knowledge to implement more effective pest control solutions by targeting pest vulnerabilities.
  3. Combination of techniques – the cumulative effectiveness of controls provides greater levels of pest controls. By combining a pest control which is for example 60% effective with another which is 30% effective, we can achieve a solution which is 90% effective, and this is far more effective than any solution employed on its own.
  4. Limiting pest populations and damage to acceptable levels – setting realistic pest control goals preserve natural controls, and are much more achievable. Eliminating a pest species is not practical, in fact it’s quite impossible, as nearly a century of  industrial agricultural chemical usage has proven, which is why we still have pests. The goal is not to eliminate every pest, it’s to preserve a crop. If pest populations are reduced to the point where the damage is not significant, and natural pest predator insects are kept alive to reduce pest populations naturally, then the goal can be considered achieved.
  5. Eliminating or significantly reducing the use of pesticides – reducing chemical use minimises cost as well as risks to people, non-target specie and the environment.

 

There are many control methods available to use in formulating IPM solutions, and in the next section we will examine each in detail.

Mechanical and Physical Controls

These controls block pests out, make the environment unsuitable for them, or kill them directly.

Physical controls include:

  • Manual methods – hand removal of small pest infestations, disease infected or pest infested leaves, or hosing pests off.
  • Barriers – netting, fencing, electric fencing, tree banding, fence spikes, root barriers, mulches for weed control, sprays which create pest barrier.
  • Traps – tree glue banding, tree cardboard banding, pheromone traps, sticky traps, newspaper traps, snail traps.
  • Heat based – boiling water or flaming weeds, soil steam sterilization for diseases.

 

Mechanical controls include:

  • Mechanical traps, such as rodent traps (lethal and non-lethal) and possum cage traps.

 

An Example of Physical Control – Calcined Kaolin

Calcined Kaolin, sold as Surround WP in the agricultural sector, and under various other names in the consumer gardening industry, is a form of clay, and is certified for use in organic gardening. It forms a white film over stems and leaves, reflecting the sun’s rays to prevent fruit sunburn, which is it’s traditional agricultural use.

This natural substance also acts as a barrier to pests, and has been used for this purpose by European organic farmers for quite a while now. The layer of calcined kaolin makes it hard for insects to walk on and presents an unnatural surface for them to interact with, causing irritation, confusion and an obstacle to feeding and egg-laying. It may also create a barrier which prevents fungal spores establishing on leaves.

Calcined kaolin is sprayed on leaves, stems and and fruit – avoid spraying on flowers, as they don’t function to well with a layer of clay over them! It’s effective in control of:

  • Gall Wasp
  • Codling Moth and Oriental Fruit Moth
  • Leafhoppers
  • Powdery Mildew
  • Stink Bugs
  • Thrips

For control of gall wasp, spray on new green shoots and branches which the pests lay their eggs into, they can’t attack branches when they have hardened off and become woody. Can be combined with a scent-based yellow sticky gall wasp trap for more effective pest control levels.

For control of codling moth, spray young fruit and respray to keep them covered. Can be combined with a pheromone-based sticky traps, insect exclusion netting bags and underplantings of nasturtiums for more effective pest control levels.

Cultural Controls

These controls are practices which disrupt the environment of the pest, reducing pest establishment, reproduction, dispersal, and survival. Many of these methods work by improving soil and plant health, remember that plants and soil ecology can naturally control pests and diseases!

Cultural controls include:

  • Changing irrigation and fertilisation practices
  • Crop rotation
  • Selecting pest-resistant plant varieties
  • Sanitation and hygiene – removing infected plant material and fallen fruit
  • Eliminating debris where pests can hide, or locating wood piles and other materials away from crops
  • Removing weeds which are hosts to pests
  • Companion planting – pest repellent and beneficial insect attracting plants

 

An Example of Cultural Controls – Citrus Leaf Miner

Citrus leafminer moths only attack new growth flushes in summer and autumn. Once leaves harden off, pest can’t mine into them.

To control citrus leaf miner:

  • Fertilise citrus in late winter to promote strong growth in spring, when citrus leafminer is absent or in extremely low numbers.
  • Peak pest periods occur in late summer and autumn, so to reduce new growth during these times, avoid over-fertilizing, using high nitrogen fertilizers or overwatering in summer and autumn. Use just enough fertilizer and water to support normal growth, but no more than that.
  • Spraying horticultural oil on new growth flushes of leaves deters citrus leafminer from laying their eggs, as they avoid surfaces sprayed with oil. Begin spraying new summer growth as soon as it emerges, before the leaves reach 10 mm (3/8”) in length.

Biological Controls

Biological control agents, the natural enemies of pests, can be use to keep their populations in check.

A wide variety of organisms are used for biological control of pests:

  • Ladybirds
  • Lacewings
  • Hoverflies
  • Predatory mites
  • Parasitic wasps
  • Nematodes
  • Bacteria

 

Listed below are the various categories of biological controls organisms used commercially and the pests that they control.

Please note this is not an exhaustive list, and some of these biological controls may not be available in every country.

 

Biological Controls – Ladybirds and Lacewings

Biological controls include:

  • Spotted ladybirds (Harmonia octomaculata and Harmonia conformis) for control of aphids
  • Ladybird (Cryptolaemus montrouzieri) for control of mealybugs and soft scale insects.
  • Ladybird (Chilocorus circumdatus) for control of armoured scale insects.
  • Green lacewing (Mallada signata), generalist predators, for control of wide range of pests including aphids, scale insects, mealybugs, caterpillars, whitefly and mites.

 

Biological Controls – Predatory Mites

Biological controls include:

  • Persimilis predatory mite (Phytoseiulus persimilis) for control of spider mites.
  • Montdorensis predatory mite (Typhlodromips montdorensis) for control of thrips, whitefly, other small insects and mites.
  • Californicus predatory mite (Neoseiulus californicus) for the control of spider mites, broad mite and cyclamen mite.

 

Biological Controls – Parasitic Wasps

Biological controls include:

  • Aphytis parasitic wasp (Aphytis lingnanensis), parasite for control of red scale and other armoured scale insects
  • Encarsia Parasitic wasp (Encarsia formosa), parasite for control of greenhouse whitefly and tobacco whitefly.
  • Eretmocerus parasitic wasp (Eretmocerus hayati), parasite for control of silverleaf whitefly.

 

Biological Controls – Parasitic Wasps

Biological controls include:

  • Parasitic wasp (Trichogramma carverae), moth egg parasite for control of codling moth, oriental fruit moth, light brown apple moth and other pest caterpillars.
  • Parasitic wasp (Trichogramma pretiosum), moth egg parasite for control of heliothis and other pest caterpillars.

 

Biological Controls – Nematodes

Biological controls include:

  • Entomopathogenic nematode (Heterorhabditis zealandica) for control of scarab beetle, including lawn beetle grubs, and weevil control.
  • Entomopathogenic nematode (Steinernema feltiae) for control of fungus gnats in indoor plants, nurseries, mushroom growing and hydroponic systems.

 

Biological Controls – Bacteria

Biological controls include:

  • Milky Spore (Paenibacillus popilliae) is a bacterial biological control primarily for Japanese beetle grubs.
  • BT (Bacillus thuringiensis subsp. Kurstaki) sold as DiPel and (Bacillus thuringiensis subsp. Aizawai) sold as XenTari are bacterial biological controls for caterpillars .

 

For Australian readers, at the time of writing, the following companies were operating as suppliers of biological controls:

Chemical Controls

Chemical control is defined as the use of pesticides to control pests. In IPM, chemical controls are used only when needed, and usually as a last resort, combined with other methods for more effective, long-term control.

How are chemical controls used in IPM?

  • The most selective and least toxic pesticides that will do the job are preferred, leaving possibility of escalating to stronger pesticides.
  • They are used in ways that are safest for environment and people, such as spot spraying, minimising wind drift and runoff, avoiding spraying before rain, spraying in evening to protect bees.

Selective pesticides (ones which only target certain pest species) are preferred to broad-spectrum pesticides which kill all insects, including the beneficial ones.

 

Chemical controls include relatively safe products accepted in organic agriculture such as:

  • Natural horticultural oils – these work as suffocating agents, blocking the insects breathing pores, so these only work by direct contact, they only work if the pest is sprayed.
  • Neem oil based pesticides – work in two ways, as an anti-feedant which stops the insect feeding, causing it to starve after approximately three days, and as a life-cycle disruptor, which stopes the insect developing to an adult stage and breeding, preventing the next generation of pests.
  • Pyrethrum pesticides – are non-specific insecticides and kill most insects, they remain effective for a short period, as they only have a 24 hour persistence, and are broken down and deactivated when exposed to sunlight. Pyrethrum is only organic certified when it does not contain synthetic synergists, such as piperonyl butoxide which is not organic certified!
  • Copper fungicides – such as copper hydroxide, copper oxychloride
  • Sulphur fungicides – such as wettable sulphur and lime sulphur
  • Potassium bicarbonate fungicides – note that these require a wetting agent such as horticultural oil to make them stick
  • Plant oil based herbicides – are made of geranium or pine oils, and work by stripping off the protective wax layer of leaves, causing weeds to dry out the next day, these burn leaves only which make them very effective on annuals but don’t kill the roots of perennial weeds. Repeated use will deplete the energy reserves in roots and eventually eliminate them.
  • Vinegar based herbicides – use highly concentrated vinegar, and also work by stripping off the protective wax layer of leaves, but most contain common salt (sodium chloride) which is bad for the soil!

Creating an IPM Program

There are 6 major components common to all IPM programs:

1. Monitoring – use of regular site inspections and trapping to determine pest types, numbers and damage.

2. Action Levels – set thresholds for when management action is needed, as pests are almost never eliminated completely.

3. Prevention – incorporate preventive measures (cultural controls) into existing structures and designs for new structures.

4. Pest identification – keep records to identify patterns and trends in pest outbreaks, and which pests are the problem.

5. Controls – use combinations of physical-mechanical, cultural, biological and chemical controls (last resort, least toxic first) to reduce pest problems.

6. Evaluation – assess and review effectiveness of pest management strategies.

 

The Ecological Approach to IPM Strategy

To manage a pest, it must be understood in terms of biology and ecology. Here is a series of steps to systematically develop ecologically sound pest management solutions:

  1. Identify the pest as accurately as possible.
  2. Learn about the pest’s habits, life cycle, needs and dislikes.
  3. Try to exclude the pest from the area, if possible by making it inhospitable to its survival or reproduction.
  4. Try to remove food, water and shelter which the pest uses.
  5. Locate the pest’s home and determine the travel patterns.
  6. Identify all possible control options available before taking action.

This approach will work for any type of pest, whether it’s a larger animal such as possums or fruit bats, an insect in the garden, or even an indoor pest.

By utilising an integrated pest management strategy, we can realistically control pest levels much more efficiently and cost-effectively, while minimising unnecessary harm to non-target species and the environment. Working smarter, using science and systematic strategy, is a much better approach to pest control than irresponsibly reaching for the most toxic chemicals available, who could dispute that?

 

 

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