Approximately 15% of my young grafted avocado trees are clearly runts. At one and a half years old, most of my trees are near 2 meters high, while the runts are not much bigger than when planted out a year ago (30 cm). Are the runts caused by being too long in a plastic bag that inhibited taproot growth, or are they primarily genetic runts?
It's easy enough to replace them, but I'm curious to learn the cause. It seems 'once a runt, always a runt' - no fertilizer seems to help.