Diseases

  • Confidor for pest control   Our Flat Seedless Persimmon has just finished producing this year thanks to an early spray of Confidor just after fruit set to control the Fruit Spotting Bug so we had an excellent crop. I used nylon stockings to keep fruit fly and birds from them. The stocking leg was able to be wrapped over the fruit 3 or 4 layers thick. The bats still were able to suck/eat 3 of the fruit through the stockings but this was stopped by hanging wind chimes and tinsel strings in the tree. We still had landings after that but a step ladder left erect close to the tree seemed to keep them right away. Next year I’ll try motion sensor lights; they work well except windy days set them off.
     
  • Flying Fox  My favorite store, ALDI, had rechargeable spotlights on sale at $24; 55watt halogen searchlights, the bats were like stunned mullets and the toads become totally paralyzed. The trees look very different in its light and what was very noticeable was that fruit and flowers really stand out. It’s a great way to find those hard to see fruit. It was the first time I’ve been able to see how nimble bats are through the trees once they recover. If you’ve got a strong spotlight give it a go as you will be surprised how different it all looks.
     
  • Damping off  in seedlings This can happen if you try to grow certain seedlings too late in the summer and they are not mature enough in the autumn to fight off the fungals.  Fungicides labelled for damping off will help but air circulation around the plants and refraining from overhead watering later in the day, are very important in preventing it.
     
  • Having a problem with black spots on Pawpaw? 
    Small black spots = cold
    Large black spots = anthracnose
     
  • Dieback   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 Neofusicoccum 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 Botryosphaeriaceae 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 shoots should develop behind the pruning cut.  Ref:  George Allen
     
  • Dieback  On Quantum there was a segment on Phytophthora in rain forests in North Queensland and the conclusion was that the disease was present only in disturbed soil that became alkaline. Maybe by maintaining an acid soil we might be able to control it in our trees.
     
  • An effective solution for fungal problems is to change the pH on the surface of the leaf. This is done by spraying one day with bi carb soda and the next with apple cider vinegar - diluted of course. This has the effect of changing the pH rapidly and fungus finds it hard to handle.
     
  • Mango Spray Schedule   Bruce at Wamuran Co-Op says the spray schedule for Mango is: Copper Oxy and Mancozeb 25gm of each in 10 litres every 7 days in wet weather and 10-14 days in fine weather – stop spray a fortnight before harvest.
     
  • Mancozeb   A useful tip that came from one of our members was that spraying with Mancozeb after physical damage was effective in enabling the repair of plants and fruit. The use of copper sprays tends to accentuate the damage due to the restricting effect it puts on cell division. Funguses find it hard to multiply in the presence of copper at higher rates, but so do plant cells. Mancozeb on the other hand consists of Zinc and Manganese. Zinc is beneficial to reproduction and growth and Manganese is important in plant health. Mancozeb has been passed for use on a lot of crops in Queensland, so before using it, check if it has been passed for the plant and use as per instructions. Maybe Zinc Sulphate used as a trace element spray would also help in these circumstances. Should be a great Mango season with this dry weather, no anthracnose. If it does rain when the flowers are on don’t forget to spray. Mancozeb is good on flowers. If some of your mango trees flower very early, cold damage to the embryos will cause a lot of them to abort and fall off. Just remember that you will have to supply water and nutrient to fill the fruit from here on. If you get rain then a spray of copper-oxychloride will help defend against fungal problems, and still be reasonably environmentally friendly.
     
  • Phytophthora   This is a solution to a wide spread infection of many plants that often cripples the growth and production of them and for some such as Avocados results in death. Australian state governments are recommending its use to save many species of trees from extinction; WA and SA are particularly hard hit. http://www.parkweb.vic.gov.au/resources05/05_2089.pdf
    I was very interested in the biodynamic farming practices at Philippe dufaud's place, particularly the drum of liquid compost being stirred. I was given a bottle of this compost tea from the barrel and this now forms the basis of a microbial/fungal tea mix I have brewing in a 65 litre bin. I did some research on the net & with what I thought I knew put together a compost tea brewing kit. A 65 litre bin, aquarium air pump, plastic tube & an aerator stone, this is now blowing bubbles through my tea. I’ve added composted cow manure, seaweed liquid, fish emulsion, compost & molasses plus some mulched Pitaya (which I had noticed was a good compost exhilarator) A witches brew that will be hard to check for bacterial & fungal action. On looking at the web again, I realized that this was big business & equipment could be very expensive & checks need to be carried out by a good laboratory. After much reading I suspect that given the right conditions your soils will be colonized naturally, a well composted, mineralized & mulched garden probably will over time end up with the right balance of flora & fauna - that’s if you don’t kill it by our normally heavy handedness, the use of pesticides, fungicides, chemical fertilizers that burn & digging & solarising the soil. I didn’t realize just how complex soils are; one author was saying there were 300 named species of earth worms in Australia & he believed there were at least twice that many. In a plot at Samford they found 23 species, the weight of bacteria in a hectare of soil is about the same as 2 cows, there are vast amounts of fungus & other living creatures that live in balance & it is they that we owe the fertility of the soil to, & also our own existence. Think twice about how you use your soil; it is the foundation to our life & much abused by our ignorance & arrogance.    Ref: George Allen 
     
  • Powdery Mildew in Mangoes  Signs to look for are when they completely lose their first flowering but put out a second flowering. You’ll usually see a white residue and the panicle flowers are brown and brittle. Some people spray neutral copper and a wetting agent when the panicles are almost ready to open and others swear by wettable sulphur and a wetting agent. Sulphur will give a good set.
    Copper seems to be best after the small fruit have formed and will avoid the black spots from anthracnose.
     
  • Powdery Mildew… Prior to spraying, the plant should have been watered for 2 days!
    Mix 1 full teaspoon of baking soda, 1 tablespoon of mineral oil, half a teaspoon of dishwashing soap or insecticidal soap, 4 litres of water.
     
  • Milk Spray Recipe for Mildew
    12 cups full cream milk to 1 cup water. You could add 1tsp bi-carb also to it.
     
  • Yates Pest Oil:  Do not use if shade temperatures exceed 32°C (35°C for citrus) or when soil is dry and plants are suffering from moisture stress. Do not pick edible fruits for 1 day after spraying. Do not spray on Glen Retreat mandarins. Do not apply for at least one month after spraying with Lime Sulphur or Sulphur.
     
  • White Oil recipe   Cup of oil, cup of water, a few lux flakes - mix in a vitamiser then dilute it 10:1 when you go to use it.
     
  • Using the Leaves of the Horseradish Tree as a fungicide - Moringa oleifera  Choose leaves that are free from disease. Wash and clean the leaves, chop up finely and mix in water, 1kg leaf to 3 ltrs water; let it stand overnight, strain then spray early morning on infested plant parts. For Anthracnose, Early blight, Fruit rot, Leaf spot. Always test the plant extract formulation on a few infested plants first before going into large scale spraying. When adding soap as an emulsifier, use a potash-based one.  Wear protective clothing while applying the extract. Wash your hands after handling the plant extract. References  * Sangatan, P.; Sangatanan, R. (2000): Organic fungicide. How to process/prepare organic fungicides. Practical guide to organic pesticides.  Technology and Livelihood Series. Busy Book Distributors, Quezon City.