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 Frequently Asked Questions
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1. Selective Herbicides
Sanonda selective herbicides kill certain targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often based on plant hormones.
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2. Total Herbicides
For non-selective weed control or in selective weed control in growing crop plants due to the development of crop plants that are resistant to it.
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3. Insecticides
For non-selective weed control or in selective weed control in growing crop plants due to the development of crop plants that are resistant to it.
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4. What is "Drift"?
Drift is the movement of a pesticide through air, during or after application, to a site other than the targeted site of application. In most cases, this movement is limited to the edges of the field or fence row. However, under certain conditions, off-target movement may effect areas at greater distances from the field. Problems occur when this movement affects a sensitive crop or another person's property.
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5. Which factors affect drift?
Drift is influenced by a number of factors that usually may be grouped into the following catagories: 1) Spray Characteristics 2) Equipment and Application Techniques used 3) Weather 4) Operator Care and Skill.
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6. In which way does the droplets size affect drift?
Spray droplet size is by far the most important factor affecting drift. Spray droplet diameters are measured in micrometers, usually referred as microns. A micron is a 1/1,000th of a centimetre or 1/100,000th of a meter. For reference the thickness of a human hair or a sheet of paper is roughly 75 microns.
Research shows there is a rapid decrease in the drift potential of droplets greater than about 150 to 200 microns. Droplets size where drift hazard becomes insignificant depends on wind speed, but lies in the range of 150 to 200 microns for wind speeds of 1 to 15 km/h.
Spray particles under 50 microns in diameter remain suspended in the air indefinitely or until they evaporate. They should be avoided because there is no way to control deposition of these small droplets. For instance, there is no need to use small droplets when applying soil-incorporated or systemic herbicides. However, small droplets are desirable when applying insecticides and fungicides because they provide better penetration into the canopy and better coverage.
Good coverage is essential with insecticides and fungicides because of the small size of the target organism. Air-blast sprayers, which are commonly used to apply insecticides and fungicides in orchards, produce a relatively high number of small droplets. However, some of the droplets never reach their target because they are directed upward where there is no canopy.
An option to decrease drift with these sprayers is to install a baffled extension manifold that directs the spray towards the tree canopy. Most pesticide applications should attain a balance between drift reduction provided by large droplets and good coverage provided by small droplets. Recommended droplet sizes for fungicides, insecticides and herbicides are mentioned on all Sanonda product labels. A general rule for the droplet size range to be used is: Insecticides: 200-300 microns Fungicides: 150-250 microns Herbicides: 250-400 microns
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7. Which influence does the nozzle type and size have?
Most current agricultural sprayers use hydraulic nozzles to meter and atomize the liquid into drops. Hydraulic nozzles produce a wide spectrum of droplet sizes ranging from under 10 to more than 1000 microns. Drift can be minimized with nozzles that produce relatively large droplets, but still give sufficient penetration and coverage of the target. For example, flood-fan and wide-angle full-cone nozzles produce far fewer drift-prone droplets than hollow-cone and flood-fan nozzles. However, flood-fan and full-cone nozzles do not provide adequate control when applying contact herbicides, insecticides and fungicides.
Nozzle manufacturers have developed "extended range" flat-fan nozzles and new cone nozzles that are capable of producing relatively large droplets with adequate spray coverage.
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8. Which effect has the nozzle orientation?
Orientation of nozzles is not a critical parameter for ground applications, but plays an important role in reducing drift from aircraft applications. When a nozzle is pointed backwards towards the tail of the aircraft, larger droplets are produced. The same nozzle will produce medium droplets when pointed downwards and smaller droplets when pointed in the airstream.
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9. Which effect does the spray height have?
Small spray droplets have low inertial energy, making them highly susceptible to drift. In addition, wind velocity is usually greater as above-ground height increases. Therefore the closer the nozzle tips are to the ground, the smaller the likelihood of spray pesticide drift.
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1. What is Herbicide resistance?
Evolved resistance is understood as the ability of a plant population to avoid being affected by a herbicide as a result of continuous or frequent application of the herbicide for long periods. This type of resistance differs from that observed when a species is not controlled by a herbicide to which it has never been exposed (natural resistance).
Evolved resistance will therefore refer to the population of a species that was susceptible before and that, after prolongued use of the herbicide, can no longer be controlled with normal rates or even overdoses.
There are currently at least 55 estimated weed species in more than 20 countries that have evolved resistance to this group of herbicides. There are weeds resistant to practically all the families of important herbicides. Even when the number of herbicide resistance cases has been increased substantially , it has not yet reached the alarming levels attained with insecticides.
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2. What is Selective Pressure?
Selection pressure is the result of effective mortality, that is, the mortality rate in terms of seeds or disseminating agents present at the end of the growth period, not immediately after herbicidal treatment. If resistance genes are already found in a population; the greater the effective mortality, the greater the probability of selecting resistant individuals. It is considered that genes coding for herbicide resistance are commonly present in weed populations even before the introduction of a herbicide and not due to the introduction of resistant individuals from other areas or created by the herbicide per se (LeBaron, 1984). It is just the selection pressure imposed by the herbicide what determines the enrichment of the population with resistant individuals.
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3. Which effect has Herbicide Persistance in the Soil?
Herbicides with long residual effect exert selection pressure on weed populations longer than herbicides that easily dissipate in soil. This is probably one of the reasons why weed populations resistant to a group of herbicides as new as the sulfonylureas have been found.
If the herbicide is not very persistent, the seed bank in the soil may decrease the probability of proliferation of the resistant biotypes by keeping an elevated population of susceptible individuals that germinate and reproduce once the herbicide has lost its biological effect. Herbicides that are inactivated immediately in the soil are not necessarily free of resistance problems. For example, there are weeds resistant to paraquat; these resistant biotypes occurred often regular and continuous applications of paraquat, a condition which is equivalent to a high selection pressure.
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4. What makes Weed Populations more or less susceptible to resistance?
A lack of fitness or decreased competitive ability of resistant weeds is frequently mentioned, as compared to susceptible populations, as yet another factor that delays the development of herbicide resistance. When a gene (the one that confers resistance) substitutes another (the one responsible for the susceptibility) in a population, the new individual is commonly less fit because it has some physiological disadvantage in relation to the original one (Holt, 1989). These disadvantages keep the new gene in a very low frequency within the population.
Therefore, it is logical to conclude that if the resistant individuals were more fit, in the absence of selective pressure (herbicide), they would be the dominant type within the population, and the herbicide would never have effectively controlled the weed species in the first place. Thus fitness could be defined as the reproductive success or the proportion of genes that an individual leaves in the genetic pool of a population.
Its two main components are survival and reproduction (Holt, 1989). In initial studies by Conard & Radosevich (1979) and Radosevich & Holt (1982), it was noted that triazine resistant biotypes produced less dry matter than the susceptible biotypes, both under competitive and non-competitive conditions. Resistant biotypes were also more affected by competition against susceptible biotypes than by competition amongst themselves.
Similar observations also have been made from weeds resistant to other herbicides, including dinitroaniline-resistant Eleusine indica (Valverde, 1989). This reduction in the competitive ability is frequently explained in terms of the inability of resistant weeds to perform fundamental physiological processes, which were affected by the alterations suffered at the sites of activity of the herbicides and which are responsible for their resistance to the herbicides. Recent studies, however, indicate that triazine resistance is not always associated with a reduction in plant vigour (Jansen et al, 1986; Schonfeld et al, 1987).
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5. What do do to avoid Herbicide Resistance?
Practically speaking, it is best to confront the problem of herbicide resistance with preventive measures. Those cultivation practices associated with high selection pressure must be avoided: use of very persistent herbicides, elevated doses, regular applications of only one herbicide, and mono-cultures that depend solely on chemical methods for the elimination of weeds.
It is advisable to rotate the herbicides with others with a totally different mechanism of action than the one previously used, as well as applying them in mixtures. When selecting mixtures, the herbicides included must each have different mechanisms of action. When the presence of resistant populations is verified at the farm level, the necessary steps must be taken to prevent their dissemination, taking special care to prevent sedd production and dispersion.
The use of the herbicide to which resistance evolved must be suspended and other control measures must be carefully selected, considering that, generally, resistance to any herbicide in particular carries a cross resistance to herbicides of the same chemical family or even to herbicides not chemically related. The grower must always read the labels of the products and wisely select the herbicides he will use.
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6. What are the factors determining the selection of Biotypes resistant to Herbicides?
Selection Pressure, Herbicide Persistence in Soil, Biological Factors and Physiological Disadvantage of certain weed populations.
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1. What are Generic Agrochemicals?
Agrochemicals based on "off patent molecules" marketed by various national and multinational chemical suppliers. The majority of the finished goods are formulated in Australia, the active constituents are imported into Australia. These active materials are certified, bio-equivalent technical grade active constituents, fully complying with the Australian registration regulations.
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2. What is the APVMA?
The National Registration Scheme operates under the Agricultural and Veterinary Chemicals (Administration) Act 1992 and subsequent Acts.
It requires companies or individuals proposing to sell or use an agricultural or veterinary chemical product to first establish that the product is safe and effective before it can be registered.
The definitions of agricultural and veterinary chemical products are set out in the Agricultural and Veterinary Chemicals Code Act.
They are very broad and do not restrict the requirement for registration to chemical products used only in agricultural production.
Registration is required for a large range of products that, in broad terms, kill pests and control disease.
Consequently, products such as swimming pool chemicals, home garden and domestic pest control products, dog and cat collars and veterinary medicines for pets are required to be registered.
Products which fall outside the scheme include fertilisers, headlice treatment for humans, stockfoods, cut flower preservatives and disinfectants. The AVPMA also reviews existing chemicals through the Chemical Review Programme, which again requires a comprehensive environmental assessment.
For further information on the registration of agricultural and veterinary chemicals in Australia, please contact:
Australian Pesticides and Veterinary Medicines Authority John Curtin House 22 Brisbane Ave Barton ACT 2600 Postal Address PO Box E240 KINGSTON ACT 2604 AUSTRALIA
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3. Are generic agrochemicals generally of inferior standard?
No active materials, formulation technologies, recipes and packaging presentation of reputed generic suppliers with technical expertise do match easily the standards of the original brands. All Sanonda product lines represent bio-equivalent, good value products, just packed in a different drum and with a different (2 colour), less fancy label. The efficacy of our products is equal to original brands.
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4. Do generic producers deserve the support of the farmers?
Yes, because it is an improper equation that just chemical companies, who have the capacity for research and development of new chemistry, deserve support of the national farming community.
The Australian farming community should have no doubt that the present patent protection law in Australia will grant the holder of the patented molecule ample opportunity to be compensated for his research and development budget and ample provision for adequate profits, worldwide.
Our customers, the growers of Australia, understand that our products provide well positioned alternatives, the better - value, quality generic brand. Sanonda (Australia) feels responsible for the performance of its product lines.
As a committed and reputed generic supplier we will be around when it comes to investigate unsatisfactory results or any problems with the performance and application of our products. In close co-operation with the technical staff of our agents, a "hands on" service and advice to the growers is available.
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5. Does the multi national industry market generics in Australia?
Yes, increasingly the multi national supply industry itself accomplishes their product range with more and more generic products, often falsely perceived by the farming community as original brands and as they were still under patent protection. The multi national chemical industry provide the distribution networks and retail chains with technical sustenance to institute generic house brands.
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6. Do multi national companies source generic products in developing countries?
Yes, considerable quantities of generic active materials and intermediates are sourced by the multi national companies in cooperation with independent primary producers in developing countries to satisfy their need for peak and emergency supplies or simply to stay competitive.
More and more Multi National Chemical companies seek joint venture agreements with these generic primary producers to increase market influence and have more control over major markets, including Australia. So it is quite likely that the Australian farmers buy so called "original brands" containing active constituents deriving from generic primary producer sources in East Europe, South East/Far Asia or South America.
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