Preventative sprays, traps, and controls you can put in place now for an abundance of fruit next season.
Now that winter has arrived and deciduous fruit trees and shrubs are dormant, it’s the best time to start planning your defence against pests and diseases.
Leaf curl
Leaf curl fungus (Taphrina deformans) can cause major problems in Tasmanian gardens. It attacks both fruiting and ornamental stone fruit trees, such as peaches, nectarines, plums, and almonds.
Fungal spores hide in soil and in the crevices of bark and branches throughout winter. In spring, they infect emerging leaves, causing twisted, blistered growth that looks like pustules. These misshapen leaves can’t photosynthesise properly, which can reduce fruit production if the infection is severe.
Unfortunately, you can’t cure leaf curl once it appears—so it’s crucial to stop the spores from spreading during winter.
Prevention
You can use either a liquid copper fungicide or a lime sulphur spray. In fact, it is recommended to use both in alternating years to reduce the likelihood of spores building resistance.
Check out our article on the difference between lime sulphur and copper spray.
Timing
Experienced gardeners swear by proper timing for leaf curl sprays. Spray once in late autumn after the leaves have fallen, then again at bud burst in late winter. If you dealt with a bad case of leaf curl last year, plan to spray up to three times over late autumn and winter.
In mid-July, take note of the weather and the likelihood of rain or wind and plan your spraying schedule accordingly. You’ll need to pay close attention to those tender buds forming. When they look like they’re almost ready to burst, that’s the time to go out in your protective gear and spray your fruit trees thoroughly.
Codling moth
That classic cartoon of an apple with a caterpillar inside? That’s the codling moth (Cydia pomonella). On our Apple Isle, codling moth can become a real problem if not managed at all stages of its life cycle. Codling moth will attack all fruiting pome trees such as apples, pears and quinces, as well as almonds, walnuts and chestnuts.
Signs of codling moth include holes in fruit with frass (caterpillar poo), chewed leaves, early fruit drop or, the worst-case scenario, half a caterpillar inside an apple you’ve just bitten into.
In winter, codling moth are in their pupal stage. They burrow into the soil around your trees and spin cocoons to ride out the cold. When the weather warms, they climb back up the tree and hide in bark. Once your apple blossoms are pollinated, moths lay eggs on leaves and young fruit. Their larvae hatch, feed, then drop back to the soil in autumn to start the cycle again.
Prevention
Winter is a great time to stop moths at their pupal stage with a multi-pronged approach. Place cardboard or thick mulch under trees to prevent moths from climbing up trees. A band of hessian wrapped around the bottom trunk can also be an effective control, as moths will shelter in the hessian. Simply replace the hessian every fortnight.
Set out pheromone traps in September. These attract and confuse male moths, stopping them from mating.
After blossoms finish, inspect leaves and fruit. If you spot insect damage, spray with Bacillus thuringiensis (Dipel). This naturally-occurring bacteria stops caterpillars from eating and damages their gut. Dipel will wash away with rain, so it is essential to reapply the spray every week as needed. Alternatively, you can use chemical controls such as Yates Success Ultra, but be sure to spray such chemicals in the cool of the evening, once beneficial pollinators are not active.
Remove all fallen leaves and affected fruit from around your trees in autumn.
Rust
Rust is another fungal disease that Tasmanian gardeners often deal with. Spores survive on fallen leaves and in soil, or travel on the wind until they find a new host.
Rust commonly infects ornamentals, such as roses, geraniums, and hollyhocks, and edibles, such as raspberries, beans, and garlic.
Look for reddish-orange pustules on leaves. Heavy infections can weaken plants, making them more vulnerable to pests and other diseases. Yields from food crops may also drop.
Prevention
Above all methods, garden hygiene is key to effective rust prevention. Remove rust-infected leaves regularly. Don’t compost affected ornamentals; bin them instead. Rotate crops in veggie beds to stop the fungus from taking hold.
Water close to the soil to keep leaves dry. Appropriate spacing between plants, air circulation and tonics that boost plant resilience will also go a long way to discourage rust.
In winter, spray liquid sulphur on raspberries before they start flowering or fruiting. For vegetables, spray a 1:10 milk-to-water mix on healthy leaves as a preventative. But if rust takes over, you’ll need to bin the infected plants to keep the rest of your garden safe.
