Fertiliser Tips

  • Fruit Trees that are flowering but not setting fruit. Ray Johnson says a grower gave him some CaB to try out, which is a Calcium Boron mix and where once he got very few Grumichama, his tree is now loaded. Spray it on all your flowering fruit trees.
  • Colin Campbell says that if you are using organic fertilisers exclusively, they do tend to raise the pH more than chemical fertilisers so sprinkle a little sulphur around every second year.
  • Bruce Benson the President of the Capricorn Club says they’ve had a few problems following the heavy summer rains which has resulted in the leaching of Boron and Molybdenum.
    Boron helps move calcium through the plant and improves the viability of pollen and setting of fruit. Best way to apply boron is to use 5gms of Solubor or a level teaspoon dissolved in a 10 litre watering can per medium sized tree and applied around the dripline. Calcium improves the internal quality of the fruit. Apply these trace elements to all your fruit trees this year prior to the commencement of flowering. These elements are only required in small amounts – don’t apply too much as you risk injuring your plants.
    Molybdenum aids in the plants uptake of Nitrogen. A shortage of this trace element is not very noticeable in tree crops but in short lived small crops such as curcurbits, it is very critical. Molybdenum (Sodium Molybdate) can be applied in the same manner.With the cool weather this winter, most fruit trees should flower well so get your trees ready now while they are resting. He’s found the best organic fungicide spray “Eco-carb” combined with copper hydroxide. This combination works two ways. The Eco-carb which is activated Potassium bicarbonate, is very alkaline and consequently kills the fungi. Copper Hydroxide is a protectant fungicide and is to be used as a covering to prevent the entry of the fungi. This combination works well on flowers and fruit as when it is dry, the Eco-carb provides a good source of Potassium.
  • With many trees, Calcium and Boron and Zinc are also important for fruit set and retention.
  • Matt Synnott -  my Golden Sweetie Grapefruit now has very thick rind which was not always so and was wondering what is lacking by way of nutrients?
    Reply from George Allen
    Phosphorus deficiencies according to "Plant Nutrient Disorders" the below bit from DPI NSW fits in as those 2 in excess affect phosphorus. Plant nutrition, in particular the balance of nitrogen, phosphorous and potassium significantly influence peel characteristics. For example excessive nitrogen and potassium levels result in fruit which are puffy and have thick peels. An excess of nitrogen can also delay peel colour development. http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0008/137717/9-lemon-cro...
  • One of our members reports that the use of CaB on early flowering fruit trees has dramatically increased fruit set. This product consists of Calcium sucrose 10.0% & boric acid 1.0% in a liquid form that appears to be rapidly taken up by the trees.
  • We use Cracker Dust - It’s a blue metal and we mix this with fowl dung (about 3:1) but you can change it as there’s no rules but it has a number of advantages. There was an ABC programme on it. There are a lot of minerals in it and its pH is about 9 so it’s nearly as good as putting lime on the ground so you mineralise your ground.  Sheryl What’s the difference between Cracker Dust and Blue Metal? Bob   Fineness. Blue Metal is too course. I’ve found that just by putting it around trees, that the roots come up into it and it’s very inexpensive. You can use it instead of top soil because it’s easier to spread and the grass will green up where you’ve put it – put it on at anytime of the year.   Ref:  Bob Brinsmead - Tropical Fruit World
  • Boron  We were told of the use of Boron and Nitrogen many years ago by Peter Young, a spray of 1gm of Borax, 1 gm of Urea to 1 litre of water.  This had to be sprayed at very early flower bud stage.  The Boron aids the pollination and seed set of the plant.  It also is important for sugar production in the fruit and if overdone makes a great soil steriliser, nothing grows for years.
  • Boron has been a topic of great interest to me.  My chestnut orchard has areas where leaves shown signs of apparent boron toxicity with leaf and soil samples each showing signs of high boron levels.  Nut set has been poor in parts of my orchard so I was still curious there was a problem with the pollen being produced.  Foliar boron sprays are often used in parts of California by almond growers to improve pollination.  Several years ago I contacted a company by the name of Pollen Bank that does testing of pollen vitality, etc. and the lab owner was curious about chestnuts and offered to do tests on 20 samples taken from different pollinator trees to see how they would react to boron and calcium treatments, charging me a very modest charge.  One sample was dead upon arrival.  Of the remaining 19 samples, 16 showed improvement with the boron treatment and 17 showed improvement with the calcium treatment.  I was curious as to how this could be since boron levels were high in the tissue samples.  I contacted Patrick Brown at UC Davis who has often been referred to as "Mr. Boron".  It's been several years since we had the discussion so I don't remember all of the details but I remember he said there were different salt forms of boron and some are likely more beneficial for pollination than others and that the form creating my toxicity problem apparently was not being utilized well by my trees.  In addition, he explained the function of boron as helping cells "slip" as they divide, though there may be other functions he mentioned that I don't remember.   Ref: Harvey Correia - California
  • Boron toxicity has occurred from the use of poultry manure because the poultry sheds have been sprayed with insecticides containing boron.   It shows up as yellow margins on the oldest leaves with dark brown to black scorch spots between the veins of the leaves and deficiency is almost the same – the margins go yellow, the leaf crumbles and goes black and the growing tip dies.   Ref: CSIRO Growing Media by Handreck & Black
  • Boron  We use boron to correct bumps on papaya, misshapen giant guava and 'spotted' dragon fruit.  First we use it as a 'drench' and thereafter directly incorporating in the top three inches of soil slightly inside the drip line.  We have not used it as a foliar spray.  We consider boron potent as slightly too much will have serious adverse effects.  We have used boron to kill rats, cockroaches, termites and those nasty red ants that attack in 'swarms'.  Ref: Bob Bishop, Hot, Humid, Tropical, Rainy Palau
  • With any crop it’s usually applied at the 1st major flush and there’s usually a window of opportunity from flushing to flowering so during that time, try and push them as much as possible.   Ref:  Ben Waddelow
  • Salt is only a problem in areas with insufficient rain to wash it away.  For example using Muriate of Potash K-chloride is a mistake in drier climes but here where you get 1800 plus mm, sodium and chlorides ain't a big worry.  I never use Muriate preferring K-nitrate instead and second to that K-sulphate.  Ref: Paul Recher [The ‘K’ referred to here is the chemical element Potassium – Ref: Russell Reinhardt.]
  • Nitrogen fertiliser will burn away all your organic carbon in the soil so whenever you add nitrogen fertiliser in any form, you need to add a carbon source - either humic or fulvic acid, or compost at the same time – it helps to balance out – it doesn’t draw out nitrogen out of the soil. Nitrogen is a gas and you want to lock it up in the soil. Having a carbon source holds it into the soil. Just having pure ammonium or even pure fish fertiliser within a day or two, the nitrogen will just evaporate. I use foliar fertiliser in the main growing season when there’s new growth - it’s very weak - do it at regular fortnightly intervals. You’re building your brix levels up. You can feed the trees a lot more and by doing that and spraying small droplets over a leaf, it becomes rapidly absorbed into the tree within an hour or two and you can actually see changes in the plant within 4 hours. When they talk about flushing, it either means putting a lot of fertiliser and a lot of water to get that growth happening. If a tree is healthy it will ward off pests and diseases so keep fertilising small amounts which is better than large amounts as the plant can deal with it a lot better. Use stone mulch about 2½” thick white quartz $40.00 per tonne and paramagnetic basalt fines - $100.00 a tonne. Put the basalt fines down first and the quartz on top then compost around the outer ring of rocks – about 3-4 large shovels per tree and you can put it right up to the trunk. As the tree gets bigger, we can extend the ring of stone mulch. I set up a trial over about 20 different trees and I put a whole lot of different materials down as mulch: different rock sizes/particles, different wood mulches, straw, different types of sand then put the water on and let it sit for a day or two then came back and did the finger test and I was very surprised to see the difference – then when it rained, I did another finger test and its amazing how there’s such a big difference between the different types of mulches. The one that held the most amount of moisture was a combination of large 8ml quartz and very fine basalt rock. We expected other mulches to do a lot better but that one was the most effective for us. I’m an Arborist and can get wood mulch but found it broke down after a year and it had to be reapplied so putting down the stone, it didn’t break down. We found with a lot of other mulches in very dry conditions, it won’t allow penetration of a small shower of rain so if you have wood chips, it becomes a barrier so when the water rains on that spot, it will run off elsewhere. Straw mulch will soak up a lot of water but if you do the finger test, under the soil is still very dry. Some of the growth rates we’ve had by pushing the trees hard – we only had sticks when we started – no more than 300mm – and now after 3-4 months, they are up to chest height so we’re hoping that by the end of the season they will be pushing well over head height and fruiting 2-3kgs per tree so it really helps to do your fertigation through your lines and do foliar feeding. We use NTS products.  An Indian scientist I talked to spoke about having a lot of plant vigour – they believe more in pruning so they push their plants with as much fertiliser and water as possible then they’ll go through and prune very heavily so the plant doesn’t lose any vigour but it will shock the tree and it will then fruit very heavily.  Ref: Ben Waddelow
  • For those that do not have access to cheap urea, you can use ammonium sulfate, but use twice more amount per gallon than what Doc Alexis is using (ammonium sulfate is 21% N, about half than that of urea's N). You can also mix together with iron chelates and other soluble micronutrients or seaweed based organic fertilizers and apply foliarly after mildly water stressing the tree (ie, no watering until you see the leaves start to slightly roll), and follow up with normal watering.   Ref: Joe Real
  • Plant growth shaped by sugars - sugar responsible for shooting  A University of Queensland study has overturned the long-held belief that plant hormones control the shape of plant growth and shown instead that this process starts with sugar. Shoot branching in plants is a vital process in agriculture and this finding will contribute toward the Queensland Government’s goal to double agricultural production by 2040 and the global need to increase food production. Senior author on the study, Professor Christine Beveridge from UQ’s School of Biological Sciences, said this finding will help to increase crop productivity by improving plant structure. “The growth of shoots and number of branches are very important to productivity and profitability, particularly in crops like avocado, macadamia and mango,” she said. “We discovered that this process is initiated by sugar rather than hormones as previously believed. “This discovery is so simple yet it has been overlooked for nearly a century.” Previous studies have focused on the plant hormone auxin as the regulator of shoot branching. Professor Beveridge and her team showed that shoot branching can begin up to 24 hours before auxin levels change, so it cannot be responsible for initiating this process. Instead they found that shoot growth occurs when a high concentration of simple sugar (table sugar) - produced by the plant through photosynthesis - is available. “Plants have a ‘goliath’ main shoot which hoards the sugars to promote its growth,” Professor Beveridge said. “If the main shoot is damaged or removed the sugars are quickly redistributed to start the growth of new shoots. “As gardeners know, deliberately removing the main shoot will direct a plant’s growth outward rather than upward, which can be very important in agriculture.” UQ is working with The Queensland Alliance for Agriculture and Food Innovation (QAAFI), Horticulture Australia Limited (HAL), NSW Department of Primary Industries and the Queensland Department of Agriculture, Fisheries and Forestry (DAFF) to transform the productivity and profitability of tropical and subtropical tree crops. Dr John Wilkie, Principal Horticulturalist and head of this initiative within DAFF, said that this discovery would aid further research into how tree crops divide sugar between tree growth and fruiting. “Manipulating the number of branches can optimise the production of fruit and seeds, leading to greater agricultural productivity,” he said. The research was published in the Proceedings of the National Academy of Sciences on 7 April 2014.