Diseases

by admin | April 1, 2020 10:41 pm

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
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.
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.
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 32Â°C (35Â°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.

Source URL: https://stfc.org.au/articles/diseases/