Because a California avocado tree does not have a dormant season, and because three two-year growth cycles occur simultaneously on the tree, an avocado tree is constantly balancing its resources in order to provide for those three growth cycles. Thus, what occurs in any one growth cycle can have repercussions on the other avocado growth cycles and therefore affect avocado crop size and quality.
Summer vegetative shoot growth
- During the summer season, the avocado tree produces the greatest number of floral shoots — 75% of the next year’s floral shoots, in fact.
- Summer vegetative shoots also produce 80% of the determinate floral shoots — those shoots that are most productive.
- The more summer vegetative shoots an avocado tree has, the greater the return bloom and yield.
- Summer vegetative shoot growth can be inhibited by the setting and development of the current year’s crop. It also inhibits the fall vegetative shoot growth. Excessive fruiting and flowering that inhibits floral shoot growth means a much smaller avocado crop in subsequent seasons because avocado fruit develop on new floral shoots.
The number of shoots that do NOT set fruit determine next year’s harvest
Here's an example to consider. Two avocado growers each have a tree that will produce 400 avocado fruit this year. Grower A’s crop will be followed by an off year. Grower B’s crop will be followed by another crop of 400 fruit. Why? Grower B’s tree has 400 shoots without fruit on them. These avocado tree shoots will produce summer and fall vegetative shoots and a strong bloom with determinate floral shoots. In contrast, Grower A’s tree has very few shoots without fruit. That means his avocado tree doesn’t have enough fruit-free shoots to produced vegetative shoots in the fall and spring.
- Avocado trees should have a balanced number of shoots with fruit and without fruit in order to maintain balance and repetitive productivity each year.
- Having two avocado crops on a tree at the same time (which is natural) does increase the total number of shoots with fruit, thus reducing the number of summer vegetative shoots.
Timing of pruning or removing excess young fruit affects next year’s productivity of new shoots and the third -year harvest.
- The effect of the young developing fruit (next year’s harvest) on an avocado tree is cumulative — the longer it stays on, the more it inhibits the possibility of seeing summer and fall vegetative shoots.
- If young developing avocado fruit is removed in July – August, this can significantly increase the number of summer and fall vegetative shoots that develop — and that means a more consistent crop size going forward.
- If young developing fruit is removed from September – December, this can significantly reduce the number of summer and fall vegetative shoots and, thus, subsequent crop sizes.
- Having two crops on a tree at the same time (which is natural) does increase the total number of shoots with fruit, thus reducing the number of summer vegetative shoots. Therefore, thinning an avocado crop during the summer months, can result in greater balance.