My parents had an unknown issue last yr with their raspberries that caused some of them to get a mosaic affect. They would like to avoid the same thing this yr. Any ideas as to the cause/solution?
The background is as follows:
1) These are plants that were bought approx 5yrs ago and produce larger than avg sized berries (approx .75"-1" in length).
2) The symptoms were white spots on some of the dimples that are normally the standard red color.
3) Approximately 10% of the berry crop was affected. The affected berries had (on average) 10% coverage with these white spots. The spots were completely random (sometimes centralized in a small section on one side of the berry and sometimes all around the berry).
4) In the past they had seen this occur but only on 1-3% of the crop. The question now is weather it's something that will get worse this yr regardless or if it's a symptom of some sort of nutrient deficiency that they could correct.