Custard Apple Tips

  • “Island Gem” Custard Apple by Ray Johnson of Gin Gin   Why do you want to graft an African Pride asked the local orchardist near Gin Gin. “I’ve got a tree of Island Gem and it’s better than African Pride,” he said. I was looking for another variety to graft on to my Pink’s Mammoth and this sounded like an interesting option. I hadn’t heard of Island Gem before but found a snippet in one of our library books, (“Growing Fruit in Warm Climates: by Brian Cull). He states: “Island Gem is a tree to 12 metres in diameter (that tree needs a prune!) with medium vigour. It begins fruiting in about year 4, producing heavy crops. The fruit are small, thin skinned with a high susceptibility to splitting. The flesh is of good texture, and excellent flavour with a moderate number of seeds. It is the earliest variety in the year. The local orchardist that I mentioned earlier, Barry, says it’s self-pollinating and basically trouble free. His wife calls it their $100 tree because they make that much and more at the local farmers market from this one tree. Besides doing 3 grafts on my Pink’s Mammoth. I’ve started 5 air-layers. Hopefully, they will all take, and I’ll have some to share around.
     
  • A problem with cherimoya is inadequate natural pollination because the male and female structures of each flower do not mature simultaneously. Few insects visit the flowers. Therefore hand-pollination is highly desirable and must be done in a 6 to 8 hour period when the stigmas are white and sticky. Pollination is done by hand to ensure an abundant crop. This is best done in mid-season of bloom. In early evening, collect in a small bottle the anthers and pollen from the interior of fully open male flowers with a #2 or #3 artists brush. Anthers will be tan coloured and the white pollen falling from them will be obvious. The pollen has its highest viability at the time it is shed and declines significantly with time. Immediately apply freshly collected pollen with a small brush to the flowers in partially open, female stage. If no female stage flowers are available, pollen may be saved in the sealed container under refrigeration overnight. Pollen may then be applied to female stage flowers in the morning. In large-scale operations the pollen may be mixed with inert Lycopodium spores, PVC, starch or talc powder and applied with aspirator-type Japanese apple-pollinators, to save time and pollen. Pollinate every two or three days, and only flowers easily reached inside the tree, to avoid sunburned and wind-damaged fruit. If pollination efforts are quite successful, it may be necessary to thin the fruit. Too much fruit may result in small size and adversely effect future yields.    Ref: © from the NewCROP the New Crop™ Resource Online Program. Published here under Fair Use Analysis
     
  • Met a grower from Mapleton at Terry Little’s talk who has 10 Pinks Mammoth & 20 Cherimoya and doesn’t have to hand pollinate. There are no pineapple farms nearby to attract the Nitidulae Beetle which is the usual pollinator of the Pink’s Mammoth but Terry was telling me that the beetle is attracted more to the African Pride than the Pinks. A neighbour keeps bees. Ref: Sheryl Backhouse
     
  • Defoliate trees about one month before normal budbreak (about August/September in south-east Queensland). Leaves are removed so the buds will come away a lot more quickly, thereby producing an earlier crop.
     
  • Patti Stacey from the Custard Apple Growers Association has advised that the new variety Tropic Sun on squamosa rootstock has been released. As stock is limited, trees are being supplied to retail nurseries on order from Fitzroy Nursery. Ask your retail nursery to order from Fitzroy. It is self pollinating on dwarfing rootstock. Seed count is a few more than Pinks Mammoth but much less than African Pride.
     
  • Apply fertiliser high in Potassium in March (autumn). Mix 1gm Boron with 1gm Urea per litre water and foliar spray. Thin African Pride fruit if needed.
     
  • Daley’s forum:  Hand pollination was pretty much hopeless. A few buckets of water and some liquid Potash and Silica thrown at it seemed to do the trick.
     
  • Annona - very common for annona seeds not to fill out, especially true with Atemoya. I think with hand pollination you would get more good seeds and rounder more filled out fruit. Ref: Oscar

     

  • Branch Dieback in Custard Apples.  Several custard apple orchards have recently reported cases of branch and tree dieback. Disease isolations carried out by the Department of Agriculture and Fisheries have identified two different pathogens with a possible third pathogen currently being identified. The pathogen Lasiodiplodia was identified to be causing branch dieback and trunk cankers in one orchard in Queensland in 2015. More recently Neofusi coccum parvum was identified in the Northern Rivers causing branch dieback in one orchard. Dark necrotic lesions were found under the bark surface. A clear definition of the lesion and healthy tissue can be seen Neofusicoccum parvum is a fungi in the Bot ryosphaeriaceae family. It has a wide host range that affects a range of horticultural crops and native vegetation. Neofusicoccum parvum is described as an opportunistic pathogen that often infects stressed or damaged trees. It also has the potential to spread through pruning cuts. Neofusicoccum parvum is a relatively weak pathogen that generally only becomes a problem when trees are under environmental stress. Fungicide sprays used to control other diseases in custard apple orchards will usually keep this disease under control. The spread of Neofusicoccum parvum can be limited by sterilising pruners that have come in contact with the diseased limbs while pruning and removing affected prunings from the orchard. In severe cases of Neofusicoccum parvum, or any other pathogens causing dieback, remove affected branches by cutting back the branch until clean wood can be seen. This is sometimes called “eradicative pruning” and can greatly reduce the potential spread of pathogens causing branch dieback. Healthy shoo ts should develop behind the pruning cut.    Ref:  Grant Bignall - Dept Agriculture and Fisheries
     
  • Peter Trebbin - Wide Bay area. In my last report I said I was having a few problems with Lychees dying. Well, a few custard apples have gone into decline also. There appears to be no difference between the three root stocks (squamosa, A/P or cherimoya). All trees came away well but when growth was about 100mm long they started turning yellow. I was talking to another tree grower from Bundy and he told me about trunk spraying with Phos Acid they are doing on other crops. I have trailed this on a few of the sick trees and some of the yellow trees have turned green again with new growth moving slowly. Time will tell if it is ok for custard apples.
     
  • Paul Thorne – Brisbane South Currently I have been noticing a few of my most hated pests in the mealy bugs. I have battled these pests to little avail at times as I personally believe that they cause the most economic damage on my farm out of any pest (maybe because my old trees are 30 plus years). Biological control is great but conflicts with the spotting bug controls, (Supracide, Lepterdex and for those who still have some Endosulfan). Oils may help but with the high temperatures of late one worries about phototoxic burning, I have noticed that the fruit closest to the sprayer that must receive the most spray seem to have a stained look about them. Then there is Applaud which has to be timed well to get the best use of. So the last mentioned should be your first line of defence that is ant control. Well at the prickle farm I have only ever seen ant activity on one or two trees. It has been told to me that these bastards can crawl upwards of 2 metres. Anyway I wish you well in your efforts to combat the many and varied attacks that the general public have no idea about except to want the cheapest and cleanest fruit on display. I had better stop here before climbing aloft onto my soapbox. I hope and wish all a happy New Year season.
     
  • Patti Stacey – Northern NSW  It’s a bit early to predict what the NSW custard apple crop will be like this season. Most have just finished pruning their trees and flowering has commenced. The odd fruit has appeared. The flowers are giving off a strong aroma indicating the pollen is viable so all fingers are crossed. The high temperatures last week – 33 degrees – have caused a bit of burning on new leaves. Craig Maddox gave an excellent presentation on integrated pest management techniques and updated us on the Fruit Spotting Bug R&D project. In the orchard he demonstrated the effectiveness of “trap trees” as a monitoring tool for FSB.
  • Sooty Mould in Custard Apples by Alan George
    Symptoms    The mould is superficial and may grow on leaves, twigs and fruit. Sooty Mould is the common name applied to several species of fungi that grow on honeydew secretions on plant parts and other surfaces. The fungi’s dark mycelium gives plants or other substrates the appearance of being covered with a layer of soot. Sooty moulds do not infect plants but grow on surfaces where honeydew deposits accumulate. Honeydew is a sweet, sticky liquid that is excreted by plant-sucking insects as they ingest large quantities of sap from the plant. Because the insect cannot completely utilize all the nutrients in this large volume of fluid (which is a dilute solution of carbohydrates, amino acids, minerals, and other substances), it assimilates what it needs and excretes the rest as "honeydew." Wherever honeydew lands (e.g., leaves, twigs, fruit) sooty moulds can become established. Although sooty moulds do not infect plants, they can indirectly damage the plant by coating the leaves to the point that sunlight penetration is reduced or inhibited. Without adequate sunlight, the plant’s ability to carry on photosynthesis is reduced, which may stunt plant growth. Coated leaves may also prematurely senesce and die, causing premature leaf drop. Fruits or vegetables covered with sooty moulds are edible.
  • Causal organism
    Fungi that most commonly cause sooty moulds are in the genera Capnodium, Fumago, and Scorias. Less common genera include Antennariella, Aureobasidium, and Limacinula. The species of sooty moulds present are determined by a combination of the environment, the host, and the insect species present. Some sooty mould species are specific to a particular plant or insects while others may colonize many types of surfaces and use honeydew produced by several kinds of insects.
    Occurrence and distribution
    A number of insects can produce the honeydew needed by sooty moulds to grow. Most of these are plant-sucking insects in the order Homoptera which includes aphids, mealybugs, soft scales, whiteflies, leafhoppers, and psyllids. Immature and adult stages of these insects feed by sucking sap from plants, producing honeydew. If these pests are controlled, then usually sooty mould is controlled.
    Chemical control
    Treat the scale or mealybug infestation and control ants. Use appropriate registered chemicals to control the pests causing the sooty mould.
    Orchard management strategies
    The most important control measure is to restrict the movement of ants into the tree canopy through the use of sticky bands placed around the trunk of the tree in spring. If the fruit does become covered with sooty mould it will need to be cleaned with water containing detergent and lightly brushed. Various methods have been used to clean the fruit. One grower has developed a semi-automated system with the fruit being sprayed with pressurised water to remove mould.