At this point in the blog, we are required to publicize and promote something that has become fashionable in agriculture, but with its own merits. We are talking about Trichodermas and their potential effect to maintain soil and roots with less development of pathogenic fungi, while maintaining good root development conditions.
WHAT ARE TRICHODERMAS?
The Trichoderma or trichodermas is a genus of fungi Ascomyceto division that are present in most arable land in the world.
However, in soils where the presence of organic matter is not greater than 2% (practically many current soils), the expression or beneficial potential of these fungi is practically nil.
That is why it is now being used massively as an inoculant to strengthen the plant, generally with colonies of trichodermas that adapt well to increasingly aggressive and punished soils.
The trichodermas fungi are opportunists. That is, it generates relationships with the roots of the plants to obtain its own benefit, in exchange for returning a positive or negative effect (in this case positive) to the plant.
However, the main distinction that this fungus has from mycorrhizae is that they live in the soil, not at the expense of the roots, but of other fungi that inhabit the rhizosphere. On the contrary, the latter, the mycorrhizae, need a previous root development where to settle.
Although now you also hear about mycorrhizae , they are two totally different species and they only have in common that they belong to the fungi kingdom. That is to say, that of the mushrooms.
Although the effect of mycorrhizae is more nutritional, trichodermas have their main use based on the protection of the plant against fungal attack. This is so because trichodermas are fungi that feed on other fungi.
WHAT FUNCTION DO THEY HAVE IN THE PLANT?
- Destroy the cell wall of pathogenic fungi by means of enzymes and antibiotics that are excreted into the environment.
- Parasitization and elimination of fungal hyphae.
- Generation of acquired resistance, making it suitable for foliar applications.
- Generation of suppressive soils where the expression of pathogenic fungi does not increase.
- Indirectly, stimulation of the roots to increase their capacity for assimilation of nutrients.
WHY ARE TRICHODERMAS USED AGAINST THE DEVELOPMENT OF DISEASES?
The positive effect that trichodermas have is based on the previous colonization of the soil before the installation of other types of fungi (Botrytis, phytium, rhizoctonia, etc.) that cause plant diseases.
In addition, trichodermas feed on other fungi , reducing their growth capacity and affecting the roots.
In this sense, this fungus generates a suppressive soil state where no pathogenic fungus appears at a sufficient level to cause damage to the plant.
That is why the installation of trichodermas will depend, to a greater or lesser extent, on some soil variables.
- Organic matter level. Levels below 1.5-2% greatly hinder the colonization and installation of this fungus, as it does not have enough fungi to feed on (highly mineralized soils).
- Soils with a high pathogenic load , where the colonization of this type of fungi, including mycorrhizae, is extremely difficult.
- Handles where copper for irrigation and fungicides are usually applied forcefully.
WHEN TO APPLY TRICHODERMAS IN MY CROP AND AT WHAT DOSAGE?
Trichodermas usually come in protected containers in powder form, with added agents (cellulose, graphite, etc.) that allow to keep the fungus strain in an optimal state.
Many of these products usually have an ecological certificate since they are accepted in said legislation.
The use of trichodermas is highly recommended in this type of agriculture, because there is not such a large and effective volume of phytosanitary products, and because more importance is given to the use and management of organic matter.
The guaranteed storage stability is usually 12 months in cold temperature conditions (4 to 6 ºC) and 6 months in ambient temperature conditions (15-25 ºC).
The application of trichodermas is recommended in the post-transplant. From the first days or until the next 15 days, it is advisable to apply them through the fertigation system with a small volume of water (2-3 m3 per hectare) to avoid leaching of the fungus.
The dosage will depend on the strain and the CFU (colony forming units). Most of these products include reapplications at specific moments of the crop.
WHAT STRAINS OF TRICHODERMAS ARE CURRENTLY MANAGED?
To this day and continuously, different strains of trichodermas appear adapted to different crops and soil conditions.
It is important to mention that, due to the high multiplication rate , as occurs with fungi and bacteria, it is difficult to control the introduced strain over time, even if such mutations are tried to be avoided as much as possible.
- Trichoderma atroviride , which offers a good response to control fungi such as Rhizoctonia solani and and Botrytis cinerea.
- Trichoderma asperellum (Trichoderma harzianum + Trichoderma viride).
- Trichoderma asperellum (Cepa ICC012).
- Trichoderma gamsii (Cepa ICC080).
- Trichoderma kingii
CAN I MIX MYCORRHIZAE AND TRICHODERMAS?
This is an important question that you hear a lot in the field and you don’t always have the same answer.
Although the ideal is to ask commercial houses, the mixture of mycorrhizae and trichodermas is more complex than we think and it can be done , but with conditions.
The clear concept that we have to have is that trichodermas feed on other fungi and, yes, mycorrhizae are fungi too.
By mixing them in the same treatment and phase, we run the risk that the trichodermas predominate over the mycorrhizae, or even that there is no trace of the mycorrhizae for weeks because they have been “eaten” by their fellow kingdoms.
The common process is to introduce the mycorrhiza previously to colonize the root and, after its installation (it takes a few weeks), to introduce the trichodermas. The mycorrhiza will have already developed enough to allow future survival.
- When a culture has a correctly installed mycorrhiza , the presence of trichodermas has a synergistic effect for the plant and for the rhizosphere, without negative or almost negative impact on the mycorrhiza.
- Trichodermas already installed in the soil make the application of any fungus in the soil unfeasible. In this case, applying mycorrhiza later is a waste of money.
For this case, it is advisable to apply mycorrhizae for 2 to 4 weeks (follow product specifications) before introducing the trichodermas.
WHAT INCOMPATIBILITY DO TRICHODERMAS HAVE WITH FUNGICIDES?
In general, we can think that all fungicides will affect the development of trichodermas , because they are a fungus.
Fortunately, this is the case, in the same way that not all fungicides on the market are able to control all pathogenic fungi that affect plants.
There are certain raw materials where there is clear evidence of affection to this type of fungus. Therefore, we must restrict its application or do it at least 5-7 days before introducing the trichoderma in the soil.
We put some declared compatibilities / incompatibilities of most trichoderma strains:
High compatibility: they can be mixed together.
Medium compatibility: apply trichodermas 5 days after treatment.
Low compatibility: apply trichodermas 2 weeks after treatment and avoid its application if there are already installed fungi.
- Score: low compatibility
- Bravo: low compatibility
- Switch: medium compatibility
- Thiram: medium compatibility
- Teldor: medium compatibility
- Sulfur: medium compatibility
- Previcur: high compatibility
- Ridomil: high compatibility
- Stroby: high compatibility
- Metalaxyl: high compatibility
- Mancozeb: high compatibility
- Chlorpyrifos: high compatibility
- Movento: high compatibility