Did your plums look like this last year too? Then they were infested by bladder plum or plum pocket disease. This fungal disease invades the plant during the flowering period. So now, just before the leaves start to grow, is a good time to apply Organic Multipurpose Plant Food as this supplies plants with optimum nutrition. Healthy, well-nourished plants are less susceptible to fungal disease. You must repeat the application twice during flowering. This will give you a healthy crop of fruit again.