It’s that time of year again when Australia’s fresh summer fruit is beginning to show up in wholesalers and supermarkets across the country. Apricots, plums, peaches and nectarines in particular, which the Australian horticulture industry classifies as summer fruit. These fruits are all closely related members of the “Prunus” genus and are commonly referred to as stone fruit. Production of these summer fruits totalled 161,044 t for the year ending June 2019. Peaches and nectarines make up the lion’s share of this with 119,775 t produced, followed by plums at 32,241 t and apricots at 9,027 t produced. (Australian Horticulture Statistic Handbook).
There are two key upcoming phases in your stone fruit calendar and they are the fruit fill/pre-harvest and post-harvest stages. There are some key nutrient management practices that can be taken to ensure a good quality harvest and to ensure your trees have the required nutrients available for next seasons bud burst.
Stone fruits size rapidly 2-4 weeks before harvest. During this period it is important to avoid water stress. It is equally important to ensure you supply the right nutrients leading up to and during this period to ensure you have a high yielding, colourful and tasty fruit that will maintain its quality and firmness. Nitrogen should be reduced in this phase to avoid excess vegetative growth and soft fruit. Potassium is important for colour, sugar and starch development and drives yield. Calcium is regularly supplied to the fruits during cell division, usually the first 6 weeks after blossoming. During the cell expansion or fruit fill stage, the calcium is diluted as a result of growth. Due to limited mobility in the tree the leaves are supplied easier than the fruits, therefore foliar calcium is very important to prevent disorders and maintain fruit firmness. It is important to balance these nutrients in the lead up to harvest to ensure neither quality nor yield is compromised. Phosphorus is also important for fruit colour and cell enlargement, and copper and boron aid in the uptake of calcium so ensure adequate levels are present.
Post-harvest is also a key period to apply the nutrients required to support growth after dormancy. Post-harvest nitrogen applications provide the main source of nitrogen at bud burst. Applying some phosphorous in this period ensures good root growth heading into dormancy. Calcium supports strong bud development and some potassium now will assist in bud strength and early fruit set next season. While the leaves are still on foliar apply magnesium and boron. Zinc is important as it governs the production of growth hormones and lifts photosynthetic potential. Post-harvest is a great time to get zinc into your tree’s to support next season’s growth.
There is a fantastic range of products out there to cover your nutrient needs and maximise this year’s crop and prepare for next years. Contact your local agronomist or industry expert to get a plan in place.
This article first appeared in Good Fruit & Vegetable magazine November 2020