While consumers are enjoying the glut of beautiful stone fruit in stores over the summer, for growers, thoughts turn to post-harvest care to replenish the lost reserves utilised by the trees in carrying and producing a crop, ensuring optimum tree health for high yields and quality fruit next year.
Post-harvest trees actively transfer nutrients, drawing them down to be stored as carbohydrates, setting the tree up for the next season’s growth and cropping. Carbohydrate storage mode stimulates the tree root system to take up native and soil-applied minerals actively; however, without adequate levels of specific nutrients stored during this period, bud break, flowering, and fruit set may be compromised.
The primary uptake of fertiliser, notably macro fertiliser, NPK, is through the soil via the tree’s root system. However, trace elements, in particular, are best applied in bio-available foliar formulations because the tree roots cannot generally transfer these nutrients to the required levels purely as they are added in trace amounts.
Stone fruit burst flowers before their leaves because flower buds have become environmentally triggered to break dormancy with warmer temperatures; this presents stone fruit growers with different challenges; it is critically important, therefore, that post-harvest nutritional requirements are effectively met, laying the foundation for resilient growth and high yields for the next season’s harvest.
What minerals are crucial in the Stone Fruit post-harvest phase, and Why?
The technology behind foliar nutrition has advanced greatly, the pinnacle being Glycine Chelates, systemic nutrients moving freely in the phloem or via the xylem, allowing total uptake within 3-4 hours and overcoming xylem breakdown as fruit enlarges. These enhanced application windows are critical since stone fruit is grown mainly in the colder south island, where weather can be changeable.
Biomin Boron – for proper flower bud development and fruit set.
Boron is an essential trace mineral required in all the actively growing parts of plants, especially for new leaf and bud development. As the trees enter their dormancy phase post-harvest, fertilisation with Boron is vital to ensure survival over the winter months and provide a strong start in the spring.
Post-harvest applications of Boron will directly impact the size and quality of next year’s crop, and Boron deficiencies can cause improper flower bud development, fruit deformities and stunted shoot growth – among other things.
Boron applied post-harvest will ensure the following:
- Proper growth and development of generative organs, such as pistils, anthers, and pollen.
- Stimulation of flower fertilisation, influencing fruit setting.
- Proper cell division and development of the root and shoot tips.
- Synthesis and transportation of sugars.
- Strong cell wall structures.
- Regulation of water management and nutrient uptake by plants.
Biomin Zinc – for improved bud fertility and protection during winter months.
Zinc is vital for stone fruit post-harvest as it contributes to metabolic processes that influence crop yield, fruit quality and overall plant health. In addition, adequate zinc levels in tissue will aid in hardening buds for the winter and protect them from winter injury.
Zinc is associated with the synthesis of growth hormones and in the metabolism of proteins and sugars which is so essential to ensure your trees have good reserves to support spring growth and development. Important for normal leaf development, shoot elongation and the set of any flowers, Zinc also increases resistance to low temperatures, frosts, and disease. Zinc deficiency is characterised by small, narrow leaves (little leaf), chlorosis of the leaves and shortened internodes.
Biomin Copper – for quick, efficient defoliation.
Stone fruit trees defoliate post-harvest. The leaves change colour and drop off, except that some trees tend to hold their leaves, and they drop off haphazardly over a long period. Every time a leaf is shed, it leaves a leaf scar wound that is essentially an entry point for disease-causing bacteria. So, having leaves fall off slowly can leave the tree vulnerable for an extended time.
Speeding up the defoliation process is preferable, and innovative growers can do this by applying copper as a foliar spray.
Researchers state, “Copper is a nutrient required by all plants, and copper is often deficient at the end of a growing season; however, nutritional copper is rarely applied.”
An effective application will generally cause the leaves to shed within the week, and beneficial biology applications encourage callusing. They will form a barrier over the open wounds to protect the tree from pathogens.
Copper is a heavy metal, and large quantities of cover copper products for defoliation should be considered carefully if you are interested in long-term soil preservation. A vast percentage of generic copper products used for defoliation are washed into the soil, leading to long-term soil heavy metal contamination.
The copper can kill off beneficial organisms in the soil that are vital for plant health (and next year’s fruit yield!).
BIOMIN™ Copper, on the other hand, is a foliar systemic copper, applied at low rates, that enters the plant, leaving no residue. It does NOT increase soil heavy metal levels due to its uptake efficacy and because it is in a bio-available form.
Some stone fruit varieties, such as MayGlo peaches, present extra difficulties in defoliation. However, this trial conducted in Hawkes Bay proved that using Biomin Copper alone resulted in 80% of branches having 100% defoliation and the remaining 20% having 93% defoliation. You can read more here:
Biomin Copper Defoliation Trial – MayGlo Peaches
The BIOMIN Solution
Biomin Boron, Biomin Zinc and Biomin Copper are three important glycine chelated, single-mineral products from the Biomin range that should be a part of your stone-fruit post-harvest regime. If levels are low, adding Biomin Magnesium or other secondary or trace minerals should be considered.
BIOMIN minerals are systemic and bio-available to plants, 100% soluble and absorbed within hours of application to rectify deficiencies and provide mineral nutrition when needed most quickly.
