I just purchased & planted three large (4-5 ft.) blueberry plants. The nursery where I purchased them advised to keep the plants well watered the first year, but didn't give much advice on fungal or insect control. Our local garden center recommended Horticultural Oil Spray by Ferti-lome, but the directions say nothing about when or at what frequency to spray other than "as needed." Is it possible to spray too often? Can someone help me with this? Am I using the right stuff? If so, when should I use it, and how often? If this isn't the right stuff, what should I be using and how often? I can't seem to get a definitive answer to these questions from the guys at the garden center.