Growers Forum << Archived >> Home


Can anyone recommend a suitable brand/company for a biomass burner to heat a greenhouse please ?
by iain reynolds on 4th Nov 2016 and last modified 2 years 10 months ago

Banana caterpillar has again reappeared as a serious pest in some mature orchards this season in Bundaberg. This large brown caterpillar, see photograph 1, which rests in the leaf litter under the trees during the day and climbs into the tree during the night to feed on small nutlets, can do considerable damage in a short period of time. In some areas of badly infested orchards it is difficult to find a single nutlet. Caterpillar numbers can get very high with up to 60 caterpillars per m2 of ground area having been recorded this season in one orchard. Numbers are generally higher closer to the trunk where the largest caterpillars are often found. Again this season, up to 50 3-4cm long caterpillars have been recorded within 30cm of the trunk in some orchards. We have had several outbreaks in orchards north of Bundaberg over the last 15 years where they have done considerable damage. They were a concern in one orchard last year, but this year they appear to be more widespread and are being seen in areas where they have not previously appeared.
This pest is found throughout coastal Queensland and is an infrequent pest in other crops such as bananas. Overseas it is a pest in cocoa and this has led to its alternate common name the cocoa armyworm. Banana caterpillar can often be found in low numbers in mature Bundaberg orchards around the flowering to early nut set period. They are not often noticed due to their excellent camouflage, their habit of hiding amongst the leaf litter in the day and of ‘playing dead’ when the leaf litter is disturbed. They are also difficult to see in the tree as they move relatively quickly just after dark up into the tree where they feed on the developing nutlets. When disturbed at night the caterpillars freeze or drop from the tree to the orchard floor where their camouflage makes them difficult to see.
The caterpillar is relatively easy to identify in that it is the only caterpillar pest in macadamia that hides in the leaf litter during the day. According to the literature, the caterpillar goes though six growth stages (instars) before they pupate and become moths. In the initial stages the caterpillars have brown to light black bodies with a cream strip along the side, they also have two conspicuous white spots on either side of the body approximately a quarter of the way down the caterpillar from the head. In the later stages the caterpillars are brown with a faint cream line along their sides and small black circles along the side of their body .
Control of Banana caterpillar is difficult as there is no registered spray. The emergency permit for Lannate (Methomyl ) which was granted for controlling this pest several years ago, has recently expired. It also appears to be relatively tolerant of pesticides such as Endosulphan, Lepidex and Bulldock . Anecdotal evidence suggests that these chemicals, which were applied to control fruit spotting bug while the banana caterpillars were present, reduced caterpillar numbers, but large numbers often survived. At this time the only control measure available to growers is to blow out the leaf from under the tree to remove their hiding place and to finely chop up the leaves, and hopefully the caterpillars, using a slasher or flail.
The best way to monitor for this pest is to carefully remove the leaf litter from around the base of the trunk and look for caterpillars (photograph 3). Generally there has to be a thick layer of leaf litter present for the caterpillars to hide in and areas of dense leaf litter appear to be the best areas in which to start monitoring. During period of dry weather and at high infestation numbers, their droppings, small hard cylinders, are very conspicuous amongst the leaf litter. The other method is to go out a night and look for caterpillar in the lower limbs of the trees. Once you have your ‘eye in’ they are not too difficult to spot. Another telltale sign is that after feeding the smaller caterpillars let themselves back down to the orchard floor on a long line of silk and these silken threads can readily be se en shining in a torch beam. The caterpillars may also emit a green fluid from a gland behind the head when disturbed. At present we have no economic threshold for this pest, but at numbers of 50 3-4cm long caterpillars at the base of a tree damage can be considerable.
We will put some photographs of this pest up on the website,for growers to have a look at. If you think you have this pest present in your orchard the best thing to do is contact your local Department of Primary Industries (DEEDI in Queensland and I&I in NSW) and have the pest properly indentified. We at Suncoast Gold in conjunction with your local Department can then work out if the pest is doing economic damage and can help you devise a control strategy.
by SGM Grower Services on 4th Oct 2010 and last modified 8 years 11 months ago

Reproduced with permission from Organic Gardener : May/June 2010

Glyphosate: safe or sorry?

Despite its reputation for being a relatively innocuous herbicide, recent research indicates that glyphosate may pose long-term dangers.

It is perhaps a public relations triumph that glyphosate, a non-selective herbicide designed to kill living plants, is so widely regarded as "safe". While bush regenerators maintain they couldn't do their work without it, emerging research may yet see glyphosate join the long list of pesticides that were once thought to be safe, but turn out to be harmful.

According to organic gardening expert Lyn Bagnall, "Some organic gardeners think that [glyphosate] has some sort of exemption from being labelled as a chemical". Bagnall is often asked about problem vegetable crops after people have sprayed glyphosate on the bed for weeds, and says, "I don't think they believe me when I tell them the problem is herbicide damage".

Farmers, bush regenerators and public authorities all use glyphosate, as do many home gardeners. People generally seem to believe it is harmless, biodegradable and disappears from the soil.

Glyphosate is sometimes referred to by the original trade name Roundup, which was first marketed by Monsanto in 1974, and the two names are often used interchangeably. Many companies now manufacture glyphosate products, as it is off patent. Australia has more than 300 such products registered for use, many for home gardens.

Monsanto's literature claims that glyphosate has been used safely around the world for more than three decades with an excellent reputation on environmental and human health grounds. Perhaps it's because of this "safe" reputation that it's common to see people spraying glyphosate without using protective equipment" and are made that it becomes inactive or "disappears" when it contacts soil), there is evidence that it can become unbound from soil, where it is then free to move into plants and leach out.

"It can appear in vegetable crops planted after the previous vegetation has been sprayed with glyphosate," says Australian organic advisor Dave Forrest. Agricultural soils high in phosphates from fertilisers can also have higher levels of unbound glyphosate.

Glyphosate residue in soil alters the microbial balance. Some soil experts say the effect is like a "bacterial bloom" that causes an imbalance between bacteria and fungi, creating conditions that ultimately favour more weed growth. Continual application of glyphosate has been found to reduce nitrogen fixation, damage beneficial fungi and make micronutrients less available, ultimately leading to plant diseases.

Despite this, the Victorian No-Till Farmers Association told OG that, "No-till farmers believe the effect of herbicides to soil health initially is far outweighed by the benefits of not cultivating the soil".

Safety questioned

Last year, France's Supreme Court upheld earlier decisions by two courts that Monsanto had not told the truth about the safety of Roundup. The court confirmed that Monsanto had falsely advertised its herbicide as being "biodegradable" and claimed that it "left the soil clean". [1]

Many people are not aware that glyphosate is soluble and persistent in water, where its half-life can be up to five months. It can actually be found in pond sediments for up to a year. Its residues affect the entire food chain including microorganisms, plankton, algae, molluscs and frogs, leading to an imbalance in the natural order, which causes algal blooms.

In 2003 glyphosate use was restricted in Denmark after it was found to be contaminating ground water "the country's main source of drinking water" at five times the acceptable limit.

The Denmark and Greenland Geological Research Institute found that glyphosate had sieved down through the soil without being broken down by bacteria before it reached the groundwater. [2]

In a move supported by key Canadian health authorities, more than 100 Canadian municipalities have passed bylaws restricting the use of all pesticides (including glyphosate) for cosmetic purposes such as lawns and driveways, because of health concerns about pesticide exposure. [3]

Cell death

The Pesticide Action Network Asia Pacific (PANAP) last year released an extensive report collating published scientific research on a range of health and environmental problems relating to glyphosate. These include: links to cancer, in particular non-Hodgkin's lymphoma, endocrine (hormone) disruption, genetic damage, and reproductive and developmental effects. [4]

Studies by Professor Gilles-Eric Seralini and a team at Caen University in France found that exposing human cells to glyphosate damaged and killed them. In its latest research (2009), the team found four glyphosate-based herbicides in Roundup formulations caused human umbilical, embryonic and placental cells to die within 24 hours of exposure to concentrations that correspond to low-level residues often found in food and feed. [5]

In response to the Seralini team research, a representative from Monsanto said in part: "These Petri dish experiments, like the previous related experiments from Seralini's group, have no relevance to a living animal and provide no information about real-world risks to humans. Instead, they tell us what we already know; that substances can injure unprotected cells in a test-tube.

"The experiments were conducted in very artificial conditions and the results are not relevant for proving toxicity in humans. Caffeine was used in a similar Petri dish experiment with the same results. The surfactant effects are also not surprising" surfactants found in a variety of personal care products and household detergents can alter the function of cells in Petri dish experiments.

"Glyphosate has an excellent human health and environmental profile, and a long history of safe use for over 30 years in more than 130 countries. Roundup Ready crops treated with Roundup brand glyphosate herbicide formulations are as safe as conventional crops." [6]

How glyphosate WORKS

There are several different forms of glyphosate, but the majority of commercial products contain it as isopropylamine salt.

When a glyphosate product is sprayed on a plant, it is absorbed through the foliage (assisted by surfactants, or wetting agents, in the formulation), and moves within the plant to the shoot apex, rhizomes and roots, where it is then quickly released into the soil surrounding the roots.

Glyphosate kills the plant by blocking the activity of an enzyme that is essential for it to make amino acids. Without these amino acids, the plant can't make proteins needed for life and it dies over a number of days. Glyphosate kills the whole plant above and below ground, which "can contribute to erosion problems" says Australian organic advisor David Forrest.

Trouble in Argentina

In Argentina, where an estimated 200 million litres of glyphosate is used in soybean production each year (mostly for GE Roundup-resistant varieties), the Supreme Court ordered a ban on crop spraying within 1km of residential areas in some provinces to reduce community exposure to spray drift. [7]

The legal action was initiated by the Environmental Lawyers Association, on behalf of affected communities that called for a total ban on glyphosate spraying because of health concerns.

Hidden toxins

Glyphosate formulations contain so-called "inert" ingredients, known as adjuvants. Because they are considered "inert", these are not assessed or disclosed on the product label or in Material Safety Data Sheets (MSDS). The law protects this information as "confidential", at the expense of the community's right to know all the ingredients.

The problem is, some of these adjuvants have turned out to be more toxic than glyphosate itself. In 1996, the then National Registration Authority (now APVMA), carried out a review of glyphosate products triggered by environmental concerns relating to the surfactant in some formulations (a surfactant increases the penetration of the glyphosate into the leaf cuticle).

Researchers in Western Australia found glyphosate products were acutely toxic to tadpoles and frogs at levels likely to be encountered in the environment. The APVMA reviewed 75 products and found the toxicity of the surfactants in all the formulations "was undesirably high for aquatic environments".

They required label changes to include a warning statement precluding use on or adjacent to waterways.

One study reviewed said the surfactant was: "...clearly the dominant contributor to the toxicity of Roundup and similar glyphosate formulations". [8]

Weed resistance

According to the APVMA, one issue on the regulatory horizon is weed resistance to glyphosate. Worldwide there are now 16 weeds with confirmed resistance. Some are attributing the problem to the introduction of glyphosate-resistant GE crops, and increased use of glyphosate in isolation from other weed management tools.

A new mechanism of resistance called "gene amplification" was also recently reported, with the study authors concluding that it "could threaten the sustainable use of glyphosate-resistant crop technology".9

No-till farming, with its high use of herbicides, as well as chemical fallow, is also believed to be contributing to resistance pressure.

The organic alternative

The use of glyphosate, or any other synthetic herbicides, is not permitted under organic certification standards. Organic weed control focuses on soil health and management techniques rather than the use of chemical products. Techniques permitted for weed control include grazing, mulching and slashing, flame and steam weeding, biological controls and mechanical cultivation.

Steam weeders are commercially available for use on both farms and urban environments (see our Products reviews on page 22 for details of one available brand).

Some councils are using steam weed control to reduce risks to the community and the environment from herbicides. Home-made and commercial, low- toxicity, organic herbicides are other options to consider, and at least one organic herbicide is in the pipeline.


1. BBC News: Monsanto guilty in "false ad" row (15/10/09),
2. Organic News
3. K.L. Bassil et al, Cancer health effects of pesticides, Canadian Family Physician, Vol. 53, No.10 (2007)
5. Nora Benachour et al, Glyphosate Formulations Induce Apoptosis and Necrosis in Human Umbilical, Embryonic and Placental Cells, Chemical Research in Toxicology (2009),
7. Nicolas Misculin, Argentine Herbicide Lawsuit Alarms Soy Farmers, Reuters (2009),
8. APVMA Glyphosate Chemical Review,
9. T.A Gaines et al (2010), Gene ampli'cation confers glyphosate resistance in Amaranthus palmeri,
by SGM Grower Services on 19th May 2010 and last modified 9 years 3 months ago

Over the last few years there has been an increasing interest in the use of animal manures in macadamia plantations. This interest has been driven by a desire to move away from the use of ‘chemical’ or inorganic fertliser, and/or the increasingly high cost of these inorganic forms of nutrition. There are both ‘pros and cons’ for using manures and these must be taken into consideration if you are contemplating their use.


Most macadamias in Queensland are grown on soils derived from sedimentary rocks. These soils are generally very old, inherently low in nutrition and fragile. While the red volcanic krasnozems of northern NSW, Maleny and parts of the Mary valley are younger, higher in nutrition and deeper, they are none the less still relatively fragile and can be readily destroyed by poor farming practices.

With all these soils, organic matter is the ‘glue’ that keeps the soil particles together and provides structure. It is this glue which is destroyed by poor farming practices. Organic matter is also the glue that keeps nutrients, vital to the health and productivity of the trees, stuck to the soil particles, preventing those nutrients being washed away. A good analogy is that these soils are like a piece of particle board, quite strong and resilient when the glue is in good condition, but damage the glue and the particle board will rapidly lose strength and fall apart. Once this process has started it is very difficult to reverse, a fact readily confirmed by anyone who has tried fixing a piece of furniture made out of old, water damaged particle board.

When most people think of organic matter they think of layers or leaf matter and husk on the soil surface, however the bit that that does the ‘sticking’ is actually microscopic organic acids which you cannot see. These acids are stuck to the soil particles and each other, and are the end product of a long series of biological processes that break down the visible organic matter into the microscopic particles that you cannot see. It is this continual process of organic matter (leaf, husk, wood, grass, manures, composts etc) breakdown that keeps the soil healthy – glue renewal and maintenance. While you can skip this process to some extent by adding processed organic acids, such as fulvic and humic, these are an end stage process and may only be partially contributing to the maintenance of an overall healthy soil rich in biodiversity.

The use of manures is NO substitute for the loss of organic matter rich topsoil.

In our wet warm costal environment organic matter is readily broken down and lost. In addition, the often sloping nature of many orchards makes them prone to the loss of organically rich top soil through erosion. Preserving topsoil is vital to maintain orchard productivity into the future. Unfortunately, our management practices require us to remove all organic matter from under the tree for over half the year in order to facilitate harvest. This means the time available for organic matter breakdown and entry into the soil under the tree is limited and the bare soil required for harvest substantially increases the risk of erosion. Erosion control is therefore one of the most important steps in putting in place a holistic approach to orchard management

Manures are a good source of nutrition but a poor source of carbon and it is carbon that is required to provide the bulk fuel to for the ‘glue’ manufacturing process. If you were to apply sufficient manures to try to build up soil organic matter levels, the trees would receive excess nutrients which in turn would present additional problems. Manures are therefore usually described as having a low ratio of carbon to nitrogen ratio, generally less than 10:1 and in the case of chook manure it ca be as low as 3:1. So, for chook manure this means you get three carbons for every one nitrogen and consequently you are getting a very nitrogen rich product relative to the amount of carbon.. The use of manures therefore, should not be confused with building up soil organic matter levels directly and they are no ‘magic bullet’ for halting soil degradation and tree decline. For manures to work they must be seen as only part of a holistic approach to managing the orchard. Importantly, to maximize their effect requires additional planning and hard work.

Pros of using animal manures

Firstly, there is a philosophical side to using manures as they are seen a more ‘natural’ method of providing nutrition. If you are to go down this path, it is my experience that people who are committed to using manures tend to make them work better than people who may be paying ‘lip service’ to this approach. Also, manures do not work in isolation to improve soil health and again the most successful orchards have included manures as part of a holistic approach to maintaining orchard health and productivity over the long term. In short, you need to be committed to this approach if you want it to work as getting the nutritional balance right is harder using manures than when using a chemical fertliser approach

Manures will provide nutrition only when they start to break down. This will only happen under wet or moist conditions which favour biological life. Therefore, those growing macadamias in wetter, more evenly moist environments, or who have sprinkler irrigation will get nutrient release faster and thus find it easy to manage meeting the tree’s nutritional requirements from manures. Conversely, because manures are slower to breakdown you are more likely to have more nutrition left after heavy rain compared with ‘inorganic’ forms of nutrition, where the nutrition is readily available but also readily lost. Manures are therefore a good source of providing a relatively constant background release of nutrients but the release of these nutrients is often largely dependant on factors out of your control.

Manures release nutrients relatively slowly and therefore provide small amounts of nutrient on a constant basis. There seems to be an increasing body of anecdotal evidence that ‘little and often’ is a good approach to feeding macadamia. This fits in with the conditions under which they have evolved with many of the soils having a low nutrient holding capacity or being deficient in one or more of the essential elements. Which means, under natural conditions, the trees only had access to relatively small amounts of readily available nutrition. The macadamia tree has therefore evolved good mechanisms to access scarce resources eg phosphorous, and also mechanisms for storing some nutrients. Nitrogen, for example is stored in the old leaves and is withdrawn under periods of high demand eg flowering, when the soil cannot meet the trees requirements. You can sometimes see evidence of this in a heavy flowering year when flowering is followed by the loss of old leaves a few weeks later. Macadamias belong to the family Proteacea and members of this family have developed uniquely modified roots which enable them to extract phosphorous from soils containing very low amounts of P. However, the drawback is that this highly efficient mechanism, while good in low phosphorous environments, makes them very susceptible to phosphorous induced deficiencies of other elements under high P availability conditions. These mechanisms are an adaptation to low fertility conditions and help buffer the tree from the environment and it is important that you take factors such as these into consideration when you are developing a balanced nutrition program.

Manures can stimulate biological activity in the soil and this can lead to the release of some nutrients that are bound to the soil particles. They do this by not only providing a diverse source of nutrition, including elemental, N, P, K etc for the soil organisms, but also food such as carbohydrates bound up in plant cellulose. Manure based nutrients are relatively accessible to the soil flora and fauna, as the gut flora and fauna of the animal has already partially broken down the material. The enhanced biological activity that appears to be stimulated by manures can assist in the breakdown of organic material from side delivered grass clippings, prunings and husk that are naturally being produced in the orchard and this in turn will improve overall soil health.

Manures may also assist in the breakdown of other sources of carbon, such as composts that have been brought into the orchard. However, there often is insufficient time between the application of the mulch and the need to clean up under the trees for the start of harvest for the mulch to be fully broken down and incorporated into the soil. Manures may help this process considerably as only when the mulch has broken down and been incorporated, and is no longer visible is it truly being useful. While mulches on the soil surface may prevent some erosion, reduce water loss and keep the roots cool it is the breakdown process and particularly the breakdown of the small and microscopic particles that really stimulates the soil biology and leads to the final process of making the organic ‘gluing’ compounds that bind the soil system together. In conclusion, manures may therefore act as the catalyst to start the breakdown of a carbon source (fuel) and thus drive or enhance the speed of the glue manufacturing process that in turn will start to maintain and repair our damaged and broken soils.

Cons of using animal manures

There are a number of problems associated with manures with the main consideration in macadamias being their phosphorous content. As discussed earlier, macadamias have evolved in a relatively phosphorous deficient environment and have developed mechanisms to seek out and take up phosphorous. Consequently, this makes them very susceptible to phosphorous induced deficiencies such as iron and zinc, when soil levels of phosphorous get too high. With the exception of red the krasnozem soils, which readily tie up phosphorous, once soil phosphorous levels are high it takes a very long time for them to decline. Therefore, you need to be aware that phosphorous levels may build up over time with the use of manures and there is a need to be constantly monitoring soil P levels. The only method of doing this is to use a soil test, as there is no correlation between soil and leaf P levels. There is also a difference among soils in terms of their ability to make P available to the plant. In very sandy soils P may be more readily available and become toxic at much lower levels than in, say a much heavier red krasnozem. A test has recently become available called the phosphorous buffer index (PBI) which is a measure of the ability of the soil to hold onto and release phosphorous. I strongly suggest that if you are contemplating using manures then you should get a soil test that includes a PBI tests. This will tell you not only the P status of your soil now but may help you predict how your soils and therefore your trees may react when you apply large amounts of phosphorous.

Another drawback is that the nutrients available in manures are not in the right ratio required by macadamias, with excess P, possibly too much K and insufficient N and possibly very deficient in micronutrients such as boron. To compound this the ratio of nutrients will differ not only between types of manures but also between sources of on one type of manure and possibly between loads. For example, feedlot manure may have very high levels of salt (Na and Cl) which can lead to chloride burn. They may also have very high levels of iron while pig manure may also be salty and have high levels of copper, and chicken litter may have high levels of phosphorous.

NOTE : When applying manure you need to have a good idea of what is in it and be aware of not only its potential beneficial nutrients but also the potential for toxicities, eg P and Cl, and deficiencies, eg boron.

As discussed in the pros section, it takes a while for manures to release the nutrients they contain and this will only happen under moist or wet conditions. Due to this slow release, at certain times of the year the availability of nutrients may be insufficient to meet tree demands. Manures can only really go out from the end of harvest through to November and this period coincides with the greatest demand for nutrients from the tree as it sets and grows the crop. It is also historically the driest time of year, so just when the trees need nutrients the most the dry conditions may mean that the tree is unable to get at them, despite the fact there are sufficient nutrients available in the manure on the soil surface . In order to maximize production it may therefore be necessary to supplement production during the high demand and dry periods of the year with more readily available inorganic sources of nutrition.

Manures may initially be quite ’strong’ and have large amounts of readily available ammonium nitrogen which can lead to root damage and short term toxicity issues. This can be overcome by leaving the manures to compost for a few weeks before applying, but be aware that unless you manage this composting properly, it can lead to nutrient loss which means not only will the trees will miss out, but the lost nutrients could also result in offsite pollution.

There is increasing concern regarding pollution of streams, rivers, and the ocean with farm nutrients and it is likely that same type of restrictions will come into place in SE Queensland as those recently put in place north of Mackay to protect the Barrier Reef.
Storage and application of manures is therefore going to become a major issue in the future and we will need to develop techniques to minimize the off site loss of nutrients.

Manures also represent a health hazard in that they can contain high levels of harmful bacteria such as Salmonella, which can be transferred to the nut, then though the handling system and onto the kernel. There is an increasing emphasis on food safety, and manure use is therefore likely to come under closer scrutiny in this regard. A food contamination scare in say, Japan or the USA, traced back to the use of manures, could cause untold damage to the industry, from which recovery could be a slow, painful process.

Despite these issues there is a lot to be gained by the use of manures in macadamia orchards, especially if we are to halt the long term decline in productivity which can be attributed to the decline in soil health. However, manures are a double edged sword and it will require a dedicated focus to develop the necessary techniques to successfully incorporate manures into macadamia production.

The nutrient content of both manures will vary considerably according to it’s source. In the case of chicken litter, it will also vary considerably according to it’s batch classification. Determine if you have a single or double shed batch.The chart at the head of the page shows the analysis of a "double shed" batch.

Both feedlot manure and chicken litter are quite salty, and exhibit high conductivity. This may be quite OK, but if you have a saline soil or are using salty irrigation water then it could just as easily cause trouble. We recently had an example of this, where manure was applied to a very sandy soil in September but it did not rain until December. In the meantime the grower had used trickle tape irrigation from a dam which had become progressively saltier with the drought. When it did finally rain the trees received a pulse of chloride from the manure on top of the already salty conditions and this resulted in leaf burn.

Chicken litter has a very high ammonium content and if this was to be applied directly to the trees in large amounts it could also result in ammonium toxicity and leaf burn. The analysis also shows the chicken litter to have a relatively high phosphorus content, around 1.4%, relative to the levels of nitrogen and potassium and if large amounts were applied to a soil which had a moderate or low PBI then this could result in problems with iron or zinc uptake.

In summary, you should always get nutrient analysis conducted before you apply the manures so you know exactly what you are putting on because there may be both benefits and potential risks. These risks can be managed if you have sufficient information allowing you to make informed decisions.

Prepared by : Chris Searle. PhD
For Suncoast Gold Macadamias.
by SGM Grower Services on 29th Apr 2010 and last modified 9 years 4 months ago