Update December 2011: MYCOPLASMA PNEUMONIAE INFORMATION relating to human health
To understand the extent of the research being conducted on this subject, please see this link.
Source Earth Clinic: reprint of article in PIONEER MAGAZINE
Borax Versus Killer Fungus
Conifer forests are threatened all over the northern hemisphere by the tiny, ubiquitous spores of a naturally occurring fungus called Heterobasidion annosum. This disease, better known as Fomes, has reached epidemic proportions in Scandinavia, and is a growing menace in the managed forests of Canada, United States, Britain, and Russia. Fomes rots the roots and heartwood of growing trees. It could be called the acid rain of the fungus world.
Supporting the UK’s Forestry Commission, Borax Group scientists Kieran Quill and Jeff Lloyd are fighting back against Fomes, and discovering how to do so with maximum effectiveness and economy. Their principal weapons are Tim-bor (disodium octaborate tetrahydrate) and the analytical capacity of the Borax Research laboratories.
Fomes cannot live freely in soil nor can it infect live trees except through root contact or wounds. Its spores however can colonize freshly cut stumps – both the “thinnings” which are essential as forests mature and the stumps left when the crop is finally felled.
The spores are produced by hoof-shaped fruiting bodies near ground level at a daily rate of about six million per square centimeter. Because these spores can be dispersed over distances of at least 300 miles, Fomes can be considered ubiquitous in most managed forests. Once established the fungus can remain viable in a stump for decades, posing a continuous threat to any conifer growing or planted near it. Fomes can survive both extreme cold and extreme heat.
But how are healthy trees infected? Fomes spores germinate on the stump surface, whence the fungus gradually colonizes the root system of the felled tree. From there it enters the root systems of living trees that are in contact with the stump’s roots, causing both roots and heartwood to decay, eventually killing the tree.
The fungus is almost impossible to eradicate, except by the removal of all stumps soon after felling – an expensive and rarely practicable option. However, germination of spores on the surface of stumps can be stopped by chemical and biological agents. In the past, this has been carried out manually by the tree feller, but now with increasing mechanization, the requirements have changed. Today a material is needed that can be sprayed automatically onto the stump while the harvesting machine is actually severing the tree. The material must give value for money, be easy to obtain, have low mammalian toxicity, be non-corrosive and environmentally benign.
Among several fungicides tested, borates have consistently given good control. Tim-bor (known as Tim-Bor® in North America) and borax are the only chemicals to have EPA approval for the control of Fomes in the U.S. However materials that are effective over large areas of North America may behave differently in northern Europe where rainfall, climatic conditions and forest management techniques could result in a completely different set of disease and control characteristics. In the light of this, the UK Forestry Commission and the Borax Group have carried out trials in Scotland with the object of determining borate efficacy. What is the threshold at which Tim-bor becomes toxic to the fungus? How little will do the trick?
Undiseased Sitka spruce near Peebles, Scotland were felled and their stumps were treated with Tim-bor at four percent, two percent, one percent, 0.5 percent, or with water. Twenty-four hours later Fomes was applied dropwise by hypodermic syringe.
The stumps were left to mature for a year, during which time samples of wood were regularly extracted with a core borer for borate analysis. At the end of a year, the amount of stump colonized by Fomes was measured on a one inch thick disc cut from a standard depth. Each disc was incubated at 10ºC to 15ºC for ten days.
During incubation, fruiting structures of the fungus emerge from infected wood. These can be seen quite easily under a dissecting microscope, and allow any diseased zones of the stump to be mapped. A comparison of the measured diseased areas on the sample discs provides a means of judging the success of a particular treatment.
All analytical work for the project was carried out at the Borax Research laboratories in Chessington (UK).
The results from this experiment indicate that at a borate concentration of around four percent, the mean area of infected heartwood was reduced from 22 percent to less than 0.5 percent. This represented less than one square centimeter, an insignificant inoculum. However, at concentrations of two percent and below, no significant control occurred. In an earlier experiment it was found that a concentration of five percent totally prevented infection. So a working concentration of four to five percent of Tim-bor is indicated for full disease control.
As a result of this research, Tim-bor is being assessed for full commercial application by the UK Forestry Commission, and has aroused widespread interest across Europe.”
Of Cabbages And Things
Plasmodiophora brassicae are nasty little beasts of uncertain origins. They may relate to the protozoa, single celled organisms which are neither plants nor animals, and are only a few thousandths of a millimeter wide and long. Most of their relatives in this microscopic world are harmless, but some distant cousins are Plasmodium species, which cause malaria in humans and Amoeba species which cause dysentery. Plasmodiophora brassicae’s parasitic way of life is to attack vegetables of the brassica family, causing the debilitating clubroot disease. Now, evidence is emerging that boron might play an important part in keeping its effects in check.
Crops of the brassica family are of enormous worldwide importance. Arguably they are second only to cereals in their contribution to human diet and welfare. They range from the cabbages, cauliflowers, calabrese and brussels sprouts familiar in the western world, to a wide array of leafy and root vegetables widespread in India, China and Japan. The Chinese cabbage, for example, is one of the most important foodstuffs of the Orient. Much of the world supply of vegetable oil comes from rape and mustard seed, while swedes (rutabagas) and turnips are important animal fodder crops in Europe and North America.
There wouldn’t be much of a problem hosting a parasite like Plasmodiophora if it didn’t have such rampant and dire side effects. In clubroot disease, the plant roots are distorted by massive galls, which inhibit water and nutrient uptake. The grossly deformed roots sap carbohydrates from the leaves and deprive developing flowers. The foliage turns bluish-green, then yellow and then wilts: the plant is past the point of no return and nothing can restore it to health.
Not surprisingly, this is responsible for drastic crop losses and poor quality. It is also virtually impossible, certainly in intensively-farmed regimes, to eradicate the parasite from the soil in which it spends much of its lifecycle.
When Plasmodiophora spores germinate in the soil, the tiny organisms swim around and as soon as they meet a root hair they attach and inject their own cell contents into the root. The genetic material multiplies inside the plant, and it is believed that this presence upsets the host hormone metabolism and leads to uncontrolled cell growth – almost a plant cancer. Once established and now mature, the parasites release billions of new spores back into the soil. It is a very robust lifecycle which is almost impossible to break.
There are clues too that Plasmodiophora may incorporate DNA from the host – perhaps a reason why biological control methods or genetically- induced protection methods have not yet been found. The traditional ways of controlling Plasmodiophora, either heavy liming (that is, adding quantities of calcium), alternative crop rotations or better soil drainage, similarly have only limited effect.
This is where boron comes in. The element is an essential plant nutrient, and it is well known that boron-healthy plants are better able to resist disease-causing organisms. In the case of brassicas, the important thing is to give the plant a head start, and certainly enough boron to begin with can help it resist clubroot.
But this doesn’t fully explain why crops which enjoy good boron availability seem to be able to resist clubroot significantly better. Researchers, led by Professor Geoffrey Dixon of the Department of Bioscience and Biotechnology at the University of Strathclyde, Scotland, UK have been looking into this puzzle.
They started out with three possible ideas. Does boron somehow reduce the potency of the clubroot invader directly in the soil? Might it encourage the growth and activity of soil microbes which then prey on the Plasmodiophora before they attack? Or does it actually fight the invasion or its effects within the plant itself?
The team now suspects it is actually the latter. For boron, which contributes so much for so little to plant metabolism, seems not to do the same for the parasitic protozoan. Indeed it works in the opposite way and actually slows down the lifecycle.
What boron and, less strongly, calcium (from heavy liming) seem to do is to reduce the rate at which the invaders mature inside the root and turn into secondary sporangiophores – the ones that cause the damage – whose mission is to release new generations into the outside subterranean world. Boron apparently doesn’t stop the initial invasion, but puts the harmful metamorphosis into slow motion.
Whether boron is altering the biochemical environment inside the root to make it Plasmodiophora-unfriendly, or is encouraging the plant to retaliate is not yet clear. But the effect is the same. Brassicas are given more, and often enough time to mature and establish effective roots before clubroot tumors wreak their damage.
A 15-year long series of experiments conducted by the Strathclyde team has convincingly demonstrated that a specific application of boron to the seedlings at transplanting does indeed reduce the onset of clubroot symptoms and hence protects crop yields to a significant degree.
Species by species, brassicas vary in their susceptibility to boron deficiency, but generally they are rated as vulnerable to low boron levels for general growth and health: boron supplementation is, then, important anyway.
But the new message for growers is that, in the right amount and at the right time, it keeps clubroot in check.”