Insects and Fungal issues
Most damage caused by insects and fungi is manageable and mainly aesthetic; it is mostly when pest populations become unbalanced (Usually caused by unusual weather or previous human “interventions’) that a healthy tree is in danger of dying from pests.
- Observe your plant for signs of stress – a stressed tree will not fight off insects and disease as well. Stress usually shows us first in the leaves through discolouration or shape distortion. Contact us or use reputable post identification resources if you suspect your tree is struggling.
- If a pest has been identified, look for organic solutions or cultural control. Sometimes all a plant needs is some proper pruning or correct amounts of irrigation.
- Never spray pesticides preventatively – pesticides disrupt the balance of insect or fungal populations which includes a host of insects or fungal allies; preventative use tends to set up worse infestations in the future by reducing the predator population in your local area. Always identify which pest is becoming a problem before choosing a remedy: some treatments will not be effective, especially if an insecticide is sprayed on a fungal issue, or vice versa. The best prevention is ensuring the plant has healthy soil, a preferred environmental location, and adequate moisture and nutrients.
- Timing is essential with almost every intervention, and there is no point in wasting money on ineffective treatments. Care must also be taken to follow all labels. If a pesticide like Malathion must be used to control outbreaks of insects like curculio on fruit trees, it should be applied precisely.
- Fungal diseases usually show up as powdery substances or mushroom-like protrusions, or spots, blotches, and/or discolourations on branches and leaves. Weather conditions are the top contributors – different fungi prefer different temperature, but the worst tends to spread at 25 – 30C with humidity. Harmful diseases like fireblight will kill branches from the tips of the branches inward towards the stem. Watch out for entire leaves losing their green colour, or dying branches, especially if the new growth is curled over like a shepherd’s crook.
- Irrigate the roots, not the leaves: many fungal issues are caused by leaves staying wet overnight – if you can’t avoid overhead irrigation, water in the early morning.
- Remove diseased leaves in fall – don’t compost diseased leaves or branches; particularly deadly diseases like fireblight. At the same time, it is very useful to compost healthy branch clippings and leaves near your woody plants to encourage beneficial soil organisms. These beneficial fungi and bacteria increase the health of the soil and will allow the tree to fight off pest disease easier.