How to fight apple scab - potassium carbonate forgotten ally.

Apple scab is one of the greatest threats to achieving high fruit yields of high commercial value in our climate zone. Its appearance in the orchard is basically inevitable. The level of harvest and the value of harvested fruit depend on the applied intervention and remedial measures. A common mistake is to use intervention measures preventively. Which completely defeats the purpose and can even be harmful. We use intervention measures only in the case of confirmed presence of fungi. On the other hand, preventive measures in accordance with the assumed spraying plan.

Immunization of the strain to intervention measures.

Too frequent and unjustified use of spraying can lead to the resistance of the fungus strain found in our orchard - in the case of apple scab, it is Venturia inaequalis (Cooke ) Aderh. – on the action of the agent used. This applies not only to spraying to protect against scab, but to all preventive treatments in general. The emergence of resistant strains can have consequences not only for a given farm, but also for adjacent ones. Mushrooms during the reproduction process can migrate on wind streams up to four kilometers. The emergence of a resistant strain in an orchard may be the result of last year's activities of a given fruit grower or the migration of fungi from another orchard.

Apple scab symptoms.

Symptoms of scab in the initial stage of infection are olive green spots on the leaves, then they change color to black and brown. The spots appear on the upper surface of the leaves. Similar changes also appear on fruits or embryos depending on the phase of their vegetative development. Drying and falling of leaves, as well as the transformation of spots on the leaves into bulges, is a clear signal that a given tree has been severely affected. In the case of fruits in the last stage of infection, corky overgrowths of the flesh and deep cracks appear. It does not take too much imagination to conclude that such fruits will not be appreciated by retail buyers, and also industrial customers must take into account the increased content of non-usable dry matter in the total weight of the fruit.

How to use potassium carbonate in the fight against apple scab.

One of the basic tools of Western European fruit growers in the fight against apple scab is potassium carbonate. The working liquid should be prepared by dissolving 6 to 10 kg of carbonate in 1000 l of water. The amount prepared in this way is sufficient for an effective application for a standard planted orchard with an area of ​​one hectare. Doses with a higher concentration should be avoided, as it can lead to burns on the leaves and/or rust on the fruit.

Spraying can be used regardless of the temperature. The effects of potassium carbonate do not show any correlation with the temperature of the applied liquid or the environment. However, it should be remembered that potassium carbonate, like most carbonate salts, is highly hygroscopic and therefore easily washable. Therefore, spraying should not be planned in isolation from the weather forecast. Repeating the application after heavy rainfall also seems to be advisable .

Advantages of using potassium carbonate.

Carbonate spraying is completely safe for the final fruit consumer. It does not leave residues in the fruit. Therefore, grace periods do not apply in his case. So the closer to the harvest, the more willingly it is chosen.

Also, resistance to such a simple substance does not develop in known strains of Venturia inaequalis (Cooke ) Aderh, and thus using it in a given year will not cause problems in the next year. None of the known pathogens show acquired resistance to this preparation. Its frequent use does not carry the risk of selecting a resistant strain in the orchard.

Another argument in favor of carbonate is its relatively low price, and its use in combination with copper or sulfur preparations turns it from an intervention measure into a preventive measure.

To sum up, sodium carbonate does not leave residues in the fruits of protected plants - no withdrawal periods. There is no problem of resistance in its case, no pathogens resistant to the agent have been found. Avoid spraying before precipitation and repeat the treatment after precipitation, which could wash away the agent. Potassium carbonate also works at low temperatures, and its relatively low price is another argument for its more frequent use.

Potassium carbonate available at distripark.com .

*This article is for informational purposes only. The presented description, in particular the use of the products, is exemplary and constitutes non-binding information about the characteristics and possibilities of their use/application. In any case, before using the product, consult a specialist whether the specific use is safe and justified. We do not bear any responsibility for the use of the proposed solutions, even in very similar situations.