Boron and its use in avocados: a guide for New Zealand growers

The New Zealand Kellogg Rural Leaders Programme develops emerging agribusiness leaders to help shape the future of New Zealand agribusiness and rural affairs. Lincoln University has been involved with this leaders programme since 1979 when it was launched with a grant from the Kellogg Foundation, USA.

Productivity and maximizing yields are issues that avocados growers in New Zealand are constantly facing and trying to improve. Avocado yields can be variable from year to year and the trees can fall into a cycle of biennial bearing. Growers do their best to avoid this situation and aim to produce consistent crops from year to year. Nutrition is a key aspect to having a healthy orchard that produces fruit from year to year. However, it is still an area that is relatively poorly understood by a lot of growers. Recommendations on what to apply and when varies between consultants and these can sometimes be very significant. Up to 11 fold differences in recommendations for certain nutrients for the same orchard have been seen in the past (J. Wilkinson, personal communication.). It is not surprising then that some growers are confused as to what is the best practice in regards to fertiliser practices. The area of fertiliser management is a complex one which involves the use of a range of products and nutrients. Boron is only one of the nutrients in the 'package' that growers require. As boron is a micronutrient, it is not required at the same level as the major nutrients nitrogen, phosphorous, potassium, calcium and magnesium. However, because it is know to have an effect on flowering and fruit set, it is a nutrient that is of interest to growers in the quest to maximize yields. This paper aims to review the research that has been carried out on boron over the years and present it in a way that is understandable and useful to avocado growers.