Iron Bacteria: In your water will stain everything red, rusty-red or reddish-brown? It gives the water a swampy look, an oily slick and when drunk has an unpleasant even irony taste. Does your water suffer from these symptoms; have an irony or stagnant smell? If the answer is yes your water supply system may have iron bacteria. Gallionella ferruginea, Thiobacillus thiooxidans and Thiobacillus ferrooxidans are the culprits. Iron bacteria are small living organisms which naturally occur in soil, shallow groundwater, and surface waters. These nuisance bacteria combine iron or manganese with oxygen to form rust deposits, or slime that sticks the bacteria to well pipes, pumps, plumbing equipment, the soil or your clothes.
The good news is that the bacteria are required in healthy organic soils and they are not known to cause any disease. It is the physical undesirable affects on the quantity of water a system will produce along with taste and staining that are the real problems.
Taste & Odour: Iron bacteria often produce unpleasant tastes and odours commonly reported as: “swampy,” “oily or petroleum,” “cucumber,” “sewage,” “rotten vegetation,” or “musty.” The taste or odour may be more noticeable after the water has not been used for some time.
Iron bacteria do not produce hydrogen sulphide. The “rotten egg” smell, people often associate with high iron deposits maybe created in an environment where sulfur bacteria can grow and produce hydrogen sulphide. (See article on hydrogen sulphide)
Colour: The first signs of Iron bacteria will usually be slight yellowing streaks on thick cotton products; like nappies, in the wash increasing to orange, red, or brown stains and eventually the stained colouration of the water itself. Water left standing overnight may produce a rainbow coloured, oil-like sheen on the surface.
Physical: These will include the inefficiency of equipment as the deposits slowly accumulate on the surfaces of pumping equipment on the inside lining of pipes, pressure tanks, faucets and corrosion problems. Corrosion can be the physical pitting of equipment walls close to the pumps; especially inside the pumping chambers themselves or chemical where the iron oxide reacts with other chemicals.
Prevention of Iron Bacteria: Clean house keeping is the best method of prevention. Eliminating surface water from entering the bore is the best method. Ensure all drilling equipment being used on new bores has been cleaned will also stop the transfer of affected water entering the new bore.
Surface water will always contain a certain amount of iron bacteria the secret is not giving them the environment that causes them to increase to the numbers that will their numbers to explode.
How it works: Iron Bacteria are naturally occurring bacteria found in dams, swamps, lakes, watercourses usually where the water is moving slowly. Iron bacteria are small microbes which convert soluble ferrous iron Fe+2 into insoluble ferric iron Fe+3 through a process of oxidization. This is a large group of different bacteria of which Gallionella ferruginea is one of the more common ones found in Australia. The presence of micro organisms like Gallionella ferruginea, Thiobacillus thiooxidans and Thiobacillus ferrooxidans act as a catalyst by utilizing the soluble iron sulphides as an energy source thus converting the iron sulphides into sulfuric acid and insoluble Ferric iron oxide. This iron then precipitates out of the water staining the surrounding ground rusty red. First or on mild infestations the surface of the water forms oil like slick, then later it forms a rusty sludge or forms a slimy crust on the surface of the water. There presence is an indication that the soil and water is very acidic. This is most noticeable where alkaloid or base metals like calcium carbonate and magnesium are absent.
In short it works like this insoluble iron H2O + Fe2O3 → 2Fe(OH)2 + O2 Soluble Anaerobic iron (water) + (Iron[III] oxide) → (Iron[II] hydroxide) + (oxygen) Deoxygenated soluble iron, iron bacteria use that oxygen to convert the soluble ferrous iron back into an insoluble reddish precipitate of ferric iron: 2Fe(OH)2 + O2 → H2O + Fe2O3.
Where there are high levels of Manganese present in the soil or water, a similar reaction occurs with different bacteria however the chemical reactions are similar but the iron is replaced with manganese. Here the water and soil are stained black with Manganese Oxide MnO2.
Hydrogen sulphide: The acid sulphate soils are deadly to plants and animals especially fish which are usually the end process that something sinister is happening or has already happened.
Hydrogen sulphide soils are naturally occurring soils usually always sediment, with high amounts of organic matter like peat that are formed under waterlogged conditions. These soils contain iron sulphide minerals known as mineral pyrite fools gold or their oxidized products.
In an undisturbed state below the water table, acid sulphate soils are inactive. However if the soils are drained, excavated, exposed by human activity, erosion during flooding and scouring or by a lowering of the water table so that air and oxygen can enter the sulphides react with the oxygen to form sulfuric acid . (2FeS2 + 9 O2 + 4 H2O → 8 H+ + 4 SO42− + 2 Fe(OH)3)
The release of this sulfuric acid from the soil can in turn release iron , aluminium , and other heavy metals particularly arsenic within the soil or water. Once mobilized in this way, the acid and metals can create a chemical chain reaction with adverse impacts. This reaction kills vegetation, seeps into and acidifies surrounding ground water and water bodies , kills fish and other aquatic organisms. This degradation will attack concrete and steel structures breaking down the industrial structural strengths.
The sediments most prone to becoming acid sulphate soils have formed within the last 10,000 years, after the last major sea level rise . When the sea level rose and inundated low lying land. The sulphate in the seawater mixed with land sediments containing iron oxides and organic matter.
Under anaerobic conditions, lithotrophic bacteria like Desulfphovibrio desulphuricans bacteria rely on large quantities of obtained oxygen for respiration though the reduction of sulphate ions in sea or groundwater, producing hydrogen sulphide. This in turn reacts with dissolved ferrous iron, forming very fine grained and highly reactive iron sulphide crystals such as iron pyrites. Warmer temperatures provide more favourable conditions for these bacteria, creating a greater potential for the formation of iron sulphides. Tropical waterlogged environments, such as mangrove swamps or estuaries, may contain higher levels of pyrite than those formed in more temperate climates.
To sum it up the pyrite is stable until exposed to air, at which point the pyrite rapidly oxidizes and produces sulfuric acid. The impacts of sulfuric acid known as acid sulphate soil leachate may persist over a long time, and/or peak seasonally (after dry periods with the first rains). In some areas of Australia, acid sulphate soils that were drained 100 years ago are still releasing sulfuric acid and soils exposed as a result of canal developments will continue to release deadly sulfuric acid into the surrounding water ways 100 years from now.
Iron Bacteria reproduce by simple cellular division and do not need an intermediary host.
Phytoremediation: Melastoma species are an aluminum phytoremediator meaning that it can take up large amounts of aluminium from the soil. Phytoremediator plants can be used very successfully in controlling very acid soils or soils which contain toxic levels or a certain mineral. In this case the soils are acid due to high levels of aluminium in the soil. It is a safer method than using chemicals, is more cost affective, is environmentally friendly, non disruptive as opposed to physically digging the soil up, pumping water into the soil to leach the chemicals. In the case of aluminum, it cannot be done successfully done as aluminium is inert and ties itself to other chemicals. One disadvantage is that the method is reliant on a long term soft commitment which is dependant upon plant growth and the tolerance to the toxicity and bioaccumulation capacity.
Other good phytomediator plants are Cannabis sativa and Pteris vittaria which are very good for the removal of arsenic while Beetroot is excellent for the removal of boron. We used beetroot very successfully on our farm at Nana Glen to remove large amounts of boron from the soil and Atriplex nummularia for the removal of sodium which then saw us grow some of the best organic mandarins and lemons in Australia on what was some of the poorest soils in the district. Over a period of 8 years the poorest soils became the most fertile and most productive.
Fungal Diseases:
Most fungal diseases can only be positively identified with tissue analysis.
(Black) Sooty Mould: Leaves, fruit and sometimes branches have a black, mouldy appearance. The fungi causing sooty mould do not actually infect the plant; instead they grow on the sugary exudates of other insects such as aphids, brown soft scale, mealy bugs and whiteflies. The amount of sooty mould found is directly proportional to the amount of honeydew secreted by the insects. A heavy sooty mould coating on the fruit can result in a lower grade of fruit, while a heavy coating of fungi on the leaves retards growth, causing lighter flowering and reduced yields.
The best method of control is to control the insects causing the problem. This will remove the honeydew and the sooty mould will dry up and blow away.
Creating safe havens for lady bugs and Lacewing flies is the best long term solution. (See Aphids or Worms and garden Friends)
Growing organically reduces the chances of being affected due to the large number of predatory insects, healthier plants and naturally occurring antibiotic producing fungi in the soil.
Botrytis: This fungus is very easy to spot and is more prevalent in warm humid environments and where overcrowding occurs. Soft growths that are induced by over fertilizing create an environment susceptible to attack. It is the fruits which are most likely to be infected. The disease usually abates as soon as the humidity and temperatures drop.
Symptoms of Botrytis sp:
It first appears as a grey fluffy ball in or between thin skinned fruits.
Fruits may become watery and lose structure.
Fruits maybe disfigured.
The fruits are often reduced to a watery pulp.
Avoid over crowding of plants. Good aeration is the best prevention available. Ensure plants that prefer full sun get full sun.
Spray the leaves early in the morning with Neem oil.
Do not use over head watering and reduce or eliminate water for as long as possible.
If the above methods fail you can resort to a light application of copper sulfate or zinc based fungicides.
Growing organically reduces the chances of being affected due to the large number of predatory insects, healthier plants and naturally occurring antibiotic producing fungi in the soil.
Phytophthora cinnamomum (Is Greek for plant destroyer): This is an extremely aggressive fungus introduced from overseas probably on the exotic Camphor Laurel (Cinnamomum camphora). It is a good example as Australians why we need to be vigilant on bringing any unprocessed organic matter through customs. The native specie of Phytophthora are no where near as aggressive as Phytophthora cinnamomum.
The same species of Phytophthora that causes root rot can infect fruit especially fruit which lies on the ground or is close to the ground. Fruit are infected during periods of excessive rain, resulting in decayed areas that are brown, firm and leathery. Later, a white, velvety growth is seen on the surface of the fruit accompanied by a strong fermenting odour. The fungus attacks the feeder roots of plants so the plants are unable to take up water or nutrients. Phytophthora sp. are more prevalent on wet soils and in plants that prefer drier conditions.
Symptoms of Phytophthora sp:
Phytophthora sp. appears as a brown blotch with a white or pale grey ring. The circular blotch expands fairly evenly outwards.
Leaves and shoots turn brown and die.
Overall health of the plant runs down.
Large cankers form on the trunk of affected trees and shrubs.
Mycelium and spores appear as white sugary coating on trunk, stems leaves or fruit close to the ground.
Wilting can occur at anytime but is usually noticed in times of stress like droughts or the dry season when water uptake is more important and the damaged roots cannot cope.
Phytophthora Life Cycle
Prevention is the best method of control.
It is very difficult to control the spread as it is water born disease and survives in areas with an annual rainfall above 400mm.
If it is possible (subject to families and genre.) incorporate animal manures into the soil.
Good composts will include microorganisms like beneficial fungus. (Trichoderma) These fungi are strongly antibiosis meaning they will form an inter reaction with other specie to its detriment. They will parasitize other fungus and are very physically competitive in occupying new niches which suppress the growth and development of Phytophthora sp.
Very important bacteria found in compost are the Actinobacteria bacteria which is essential for the decomposition of Chitin and cellulose. They are the dominant phyla within Bacteria and produce antinomycin which is a natural soil antibiotic. They form a dense branching filament network which also aides in the blocking of outward growth of the Phytophthora.
These bacteria and fungi will suppress the activities of Phototherapy sp. and retard the diseases development.
Growing organically reduces the chances of being affected due to the large number of predatory insects, healthier plants and naturally occurring antibiotic producing fungi in the soil.
Powdery Mildew: This fungus is very easy to spot and is more prevalent in warm humid environments and where overcrowding occurs. Soft growths that are induced by over fertilizing are the leaves and buds which are most likely to be infected. The disease usually abates as soon as the humidity and temperatures drop.
Avoid over crowding of plants. Good aeration is the best prevention available. Ensure plants that prefer full sun get full sun.
Spray the leaves early in the morning with neem oil.
Do not use over head watering and reduce or eliminate water for as long as possible.
Strange as it may seem but hose the affected leaves down with clean water early in the morning.
If the above methods fail you can resort to a light application of copper sulphate or zinc oxide fungicides.
Growing organically reduces the chances of being affected due to the large number of predatory insects, healthier plants and naturally occurring antibiotic producing fungi in the soil.
A spray mixed with worm castings has proven beneficial on many types of powdery mildew.
Rhizoctonia (Is Greek for root killer): These fungi attack seeds, roots and collars of juvenile plants. It is commonly referred to as collar rot. It is more prevalent in cool, wet weather when seeds are germinating and is the scourge of the nursery industry.
Symptoms of Rhizoctonia specie
1. Seeds fail to germinate.
2. Red or reddish-brown lesions below, at ground level or just above the collar.
3. Sever wilting where the roots have been totally eaten away.
4. Fruits that are touching the ground have round brown sunken blotches
5. Roots have deep brown or black lesions and apexes.
Rhizoctonia will infect orchids so keep epiphytic orchids well above the ground out of harms way. Allow the area between the orchids and ground to dry out between watering.
Ground orchids grown in pots are best grown on tables that dry out quickly or outdoors in well mulched soils.
Orchids in the ground should have high levels of mulch and compost to encourage beneficial fungus and bacteria. (See Phytophthora)
Ensure temperatures are warm enough for germination.
I have heard good reports from orchid growers that double strength Worm Liquid or Worm Tea impregnated with Bacillus subtilis is a good remedy for the control in the early stages of Rhyzoctonia in their plants. This would certainly encourage other beneficial bacteria and fungi which may prevent and seriously suppress or retard the development of the disease.
Growing organically reduces the chances of being affected due to the large number of predatory insects, healthier plants and naturally occurring antibiotic producing fungi in the soil.
Virus or Bacterial Diseases:
Brown Spot or Leaf Spot: is caused by various fungi, bacteria or viruses. To frighten you first these are very common and over 100 different specie are known to infect citrus alone.
Symptoms of brown Spot
- Brown or red circular spots on the leaves.
- Spots turn to depressed blotches.
- Leaves turn brown and die.
Healthy plants will usually avoid getting the disease.
When the disease is first noticed remove infected branches and immediately sterilize the secateurs. Place the infected material in a bag and either burn it or take it to the refuse tip.
Ensure good composting and mulching around the trees helps in tree and shrub vigour.
Spray the infected plants with neem oil can be beneficial in suppressing the spread of the disease.
If all else fails resort to mancozeb or copper sulphate solution. This will only help if the disease is fungal or bacteria related. Viruses like the human flu if not life threatening will pass if the plants are healthy.
Growing organically reduces the chances of being affected due to the large number of predatory insects, healthier plants and naturally occurring antibiotic producing fungi in the soil.
Ink Spot: This is a fungal disease very commonly found in Anigozanthos specie found in humid areas. The fungus responsible is Alternaria alternata. Some specie like Anigozanthos manglesii are more susceptible than most the hybrids and cultivars.
The fungus appears as black ink on the upper sections of the leaves and in sever cases causes the death of the apical sections of the leaf. Severe infestations can also decrease the size and abundance of flowers.
The best method of control is a good organic soil that produces a good strong balance of beneficial fungi and healthy hardened plants rather than plants with soft susceptible foliage. A plant that we had next to our nursery that was soft due to water and nutrient run off suffered severely yet daughter plants from division growing only 16 meters away on the upper raised side never once had ink spot more than a few isolated dots. Both plants were in full sun and both plants were of approximately equal size.
Growing organically reduces the chances of being affected due to the large number of predatory insects, healthier plants and naturally occurring antibiotic producing fungi in the soil.
It is best to cull plants that consistently suffer this ugly looking disease for more resistant strains. Mancozeb or Zineb can be used to control minor outbreaks.
The Life Cycle of Bacteria is complex and varies on the Genre and species involved. Some bacteria need a host to complete their life cycle. Below is a diagram of an average host reliant Bacteria.
EB Elementary Body or the Base Cell.
RB Reticulate Body. (An Elementary body transforms into a new body known as the Reticulate Body)
CF Cryptic Form (Bacteria have the ability to transform into a cryptic stage of life if under stress as a means of survival. In other words the Bacteria are able to decode antibiotics and immune system responses which allows them to mutate or to transform into RB forms that are resistant to the antibody.)
For a range of bacteria, fungi, viruses and insect problems that attack vegetables we recommend a visit to HTTP//www.agric.wa.gov.au
This site offers a large range of photographs mostly poor quality on all the common vegetable problems in that state.
Further comments from Members:
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