L’Ampelomyces quisqualis is a microorganism used in agriculture in the microbiological fight against crop diseases, in particular thepowdery mildew. Biologically it is a division fungus Ascomycotafamily Phaeosphariaceae. This ascomycete belonging to the feosferiaceae has been the subject of studies for centuries, with the first applications in the biological fight against powdery mildew dating back to the 1930s. In recent years, intensive agriculture has resulted in the development of powdery mildew strains that are increasingly resistant to classic fungicides, thus making the potential ofAmpelomyces quisqualis as a useful ally in the biological defense of crops.
So let’s see the mechanism of action of this microorganism and on which crops it is applied.
Mechanism of action ofAmpelomyces quisqualis
The microorganism Ampelomyces quisqualis it is present both in natural environments and in the land on which agricultural crops are practiced. It feeds directly from the host’s live cells, behaving like a biotrophic mycoparasite. This fungus works by infecting the hyphae, conidiophores and cleistothecia of powdery mildew, which is another (harmful) fungus. On powdery mildew, this microorganism gives rise to the pycnidia, which are the fruiting bodies of the fungus. Wintering takes place at the picnidium stage, and in spring the fruiting body releases the conidia in the same colonies of the powdery mildew, carried by the water, such as, for example, driving rain. In practice, it infects the pathogen responsible for powdery mildew, developing inside it.
Then begins the process of formation of the pycnidium, which causes the devitalization of the powdery mildew within 2-4 days.
Environmental conditions favorable toAmpelomyces quisqualis
The optimal development of Ampelomyces quisqualis it is included in a temperature range between 20 and 30 ° C, with high ambient humidity and rain. If the season is favorable, it can complete several development cycles, spreading this sort of good infection in contrasting powdery mildew.
Effects ofAmpelomyces quisqualis on powdery mildew
Plants affected by powdery mildew typically have a whitish and powdery patina (hence the common names of fog and bad white) which progressively spreads to the entire leaf surface.
In the oidium colonies parasitized by Ampelomyces quisqualis we observe the arrest of the production of the oidium spores, with the color of the patina that turns to gray-brownish and the disease that stops and regresses.
On which crops can theAmpelomyces quisqualis
Being a specific mycoparasite of oids and having a broad spectrum of action on the most common forms of oidium in crops, theAmpelomyces quisqualis is effective againstpowdery mildew of the vineoidium of the cucurbits, oidium of the solanaceae, thepowdery mildew of rosesthe powdery mildew of the strawberry.
In particular, in the difficult struggle against that of the vine, theAmpelomyces quisqualis has shown excellent effectiveness in significantly reducing the overwintering potential of the pathogen, severely limiting infections of the following year. The action has proved effective both in open field and greenhouse crops.
Intervention technique
L’Ampelomyces quisqualis it is a microorganism already present in nature. The treatment is preventive rather than curative, and the technique involves seasonal and periodic interventions aimed at increasing natural populations. The periods for execution must be those in which powdery mildew usually arises in the crops concerned.
The treatments are all the more effective, the lower the level of inoculation of the disease. On the vine, for example, there should be no more than 3% of infected leaves. Therefore, maximum attention is paid to monitoring the health of the plants and consequently to choosing the most appropriate time to intervene.
Practical methods of use
There is currently only one authorized product based on Ampelomyces quisqualisnamed AQ 10 WGand you can buy it without needing the license required for the use of plant protection products.
The product contains the spores of the microorganism which are distributed on the crops through the water. The aqueous medium allows the rehydration of the spores and, in proximity of the host, the germination with the formation of a tube that penetrates the hypha of the powdery mildew.
To maximize the effectiveness of the product, it is advisable to carry out the treatments in the evening, thus increasing the wetting time, which must also be accurate.
The water used for mixing should have a pH between 6 and 8.
For greater effectiveness it is recommended not to mix everything with other fungicide products (copper, sulfur).
storage
Like other products for the microbiological defense of crops (for example bacillus thuringiensis, beauveria bassiana, bacillus subtilis, entomopathogenic nematodes, trichoderma), adequate conservation is essential to maintain its effectiveness over time. The advice is to strictly follow what is written on the label.
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