Nutrient deficiencies and pH imbalances cause yellow leaves on blueberries. Test your soil for pH and nutrients; visually inspect for pests and stress. Treat with soil amendments and adjust watering for plant health. Before planting blueberries, have a soil sample tested. Collect soil samples up to a year or more in advance. This allows adequate time to amend the soil, if necessary. Take samples from the top 12 to 18 inches of soil, where the roots will grow.
Blueberries require a soil pH of 4.5 to 5.5. If the test results indicate that soil pH is too low (too acidic) or too high (too basic) for blueberry production, amend the soil to improve the pH (see “Soil pH;” below). A typical soil analysis will also include phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na). Test for organic matter and for boron (B), especially in the Willamette Valley where B deficiency is common. Nitrogen (N) levels in soil are not useful because N is not added prior to planting. Instead, supply N with fertilizer after planting.

Here is an informative publication:

https://extension.oregonstate.edu/catalog/pub/ec-1304-growing-blueberries-your-home-garden

Thank you. Is it possible a mosaic virus and not minerals deficiency ?

In this Suziblue blueberry 2 years old plant,

Could it be a mosaic virus or something else , and not nutritional or pH problems ?

Avi

not likely.

Mosaic virus would be a different discoloration.