with Erica Faber
With the seasonal change of lower temperatures and shorter day lengths, flower initiation in our avocado trees has been triggered. Hormones trigger the transition from vegetative to floral buds, but it is the nutrient levels and balances that drive this reaction and the carbohydrate levels that determine the stamina of this reaction.
This pre-flowering stage is one of those critical stages that we, as growers, need to ensure the tree has all the resources it needs in order to optimise production. The following nutrients are important to apply during this time to support the imminent flower initiation as well as the current crop.
Firstly, ensure correct nitrogen levels. Too much of a good thing is not always a good thing! Excessive nitrogen in the tree at this time will swing the balance in favour of vegetative growth, thereby compromising potential flowering and fruit set.
Foliar sprays of seaweed products will boost cytokinin levels as seaweed extracts are particularly rich in cytokinins. Low cytokinin levels in relation to other hormones will inhibit floral bud development.
Avocados are an incredibly boron-hungry crop and their low flower-to-fruit ratio can be substantially improved with a foliar spray of boron at the pre-flowering stage.
Calcium fulfils many essential roles in the sexual reproduction of flowering plants. It is also called the “trucker of all minerals” because it directly affects all mineral uptake. Therefore, it is advisable to apply calcium at this stage as well, not only for the flower development and fruit set but also for its role in the current developing crop. Calcium governs cell wall strength and not only improves fruit quality but also aids in resistance to anthracnose and post-harvest rots.
Potassium is extremely important during this fruit-fill stage. Insufficient levels of potassium reduce the yield potential and quality of the crop – and ultimately our pockets!
Zinc is one of the most important elements in carbohydrate metabolism in plants. Most enzymes that play a role in carbohydrate metabolism are activated by zinc. Zinc is also an essential micronutrient for protein production in plants. One of the sites of protein synthesis is the pollen tube.
Remember to ensure compatibility when mixing your chemicals and fertilisers. If you’re concerned about any incompatibility or phytotoxicity, contact the manufacturers or do a jar or spray test.