Question: use of copper sulphate
I would like to know whether to use copper sulphate on peach trees in full vegetation
or if this practice is harmful to the plant.
Answer: use of copper sulphate
the copper sulphate it is a fertilizer and a fungicide, also used in organic agriculture; it is a non-excessively toxic product, which however remains harmful if used in large quantities. In particular, copper sulphate is generally very harmful for plants, which absorb this metal through the leaves, and can also suffer serious damage. Generally copper sulphate is mixed with lime, in order to have a pH closer to that of the leaves, and therefore less harmful; the result is called Bordeaux mixture. Even in this way, it remains a fungicide to be used with caution; on many plants, such as on the peach tree, copper sulphate and Bordeaux mixture are used only as fungicides in preventive treatments, at the end of winter, and never on plants already in vegetation; it is not used even in the period in which the plants are already well enlarged buds, because it could burn them, making the tree unproductive for the following season. In addition to this, as for any pesticide, it would be good to use the product on plants only when there are no bees, or other useful insects, in the garden, so as not to disturb them.
As for the peach, cupric-based fungicides are used on these plants only in autumn, when the leaves have already fallen, or at the end of winter, before the buds swell.