Month: August 2024

The Return of Chilli Thrips

With the onset of spring no doubt chilli thrips will be the main thing on gardener’s minds because it drove people to desperation for months. This year chilli thrips attacked blueberries, grapes, strawberries, chillies, capsicum, hydrangea, asparagus, onion, passionfruit, peaches, mango, and azaleas.

Gardeners basically threw everything they could at them to no avail, systemic insecticides, oils, soap spray, severe pruning and as a last resort removal of the plant. The despair chilli thrips caused most gardeners was on epidemic proportions.

Rob Melville from Melville’s Rose n Garden has shared his experiences with chilli thrips. Their nursery grows thousands of roses, allowing them to trial various control methods, using many sprays available to the home gardener and did a trial plot of hard pruning during summer. The solution they found will probably shock most people its so simple.

Before revealing his team’s solution, it’s important for people to understand the life cycle of Scirtothrips dorsalis (chilli thrips). They have been in WA for around 20 years and are active year-round but more prevalent in spring, summer, and autumn. They are tiny, only 2mm long with a torpedo shaped yellowish  body and wings.

When feeding, chilli thrips use a mandible to cut into the plant, inject their saliva then insert a tube that sucks up semi-digested food. It’s a punch and suck action. In warm temperatures chilli thrips can produce 18 generations in a year and females can lay up to 40 eggs during a lifetime.

Eggs are laid in the foliage and the first two stages of life (instars) occur in the foliage or buds, then they go into the ground or leaf litter for the next two stages of development (prepupa and pupa) finally appearing as a winged adults and continue to feed. The life cycle takes around 15 days. The stages of development in the ground are crucial for control.

Rob Melville found that all the sprays became ineffective after a while as the thrips developed an immunity to them. Sprays including the organic ones were killing any of the predatory insects that fed on the thrips.

He maintains the best method of control was to overhead water daily and not use any pesticides or insecticides. The thrips are so small, during the prepupa and pupa stages they actually drown in the leaf litter. Robs advice is to allow the beneficial insects that predate on thrips to build up, overhead water daily and never hard prune during the warmer months.

Tip

Predatory insects for thrips include pirate bugs, mites, ladybirds, parasitic wasps, predatory thrips, green lacewings, and damsel bugs.

Spring Legionnaires Disease Prevention

There’s the promise of warmer days in the air and gardeners will be super keen to get back out into the garden and spruce things up before the heat sets in. Bags of potting mix, mulch, compost, and soil conditioners will be lugged in and out of cars heralding  spring fever in the garden.

The recent outbreak of Legionnaires disease in Victoria is a grim reminder that gardeners need to avoid a potentially deadly bacterial infection when handling bagged and bulk soil and mulch products.

Cases of Legionnaires’ disease – a severe form of pneumonia contracted by breathing in dust from soil products contaminated with legionella bacteria – often increase at the beginning of spring as people start their seasonal planting.

Legionella longbeachae bacteria are commonly found in gardening products, including bagged potting mix, mulch, and compost. Another strain of the bacteria – Legionella pneumophila – contaminates water in air conditioning cooling towers, whirlpool spas, fountains, misting systems and shower heads.

WA Health’s Acting Executive Director Environmental Health Peter Gray said there had been 187 notifications of Legionnaires’ disease linked to garden soils and/or potting mix since the beginning of 2020. “Of these, 112 cases required hospitalisation,” he said.

The risk and severity of infection increases for older people, smokers, or those with weakened immune systems, and up to 10 per cent of cases can be fatal.

A few simple measures will help protect gardeners from the risk of infection.

  1. Always wear a disposable face mask before opening up bags or shovelling bulk soil products from a trailer
  2. Wear gloves and open the bag with scissors or secateurs (not your teeth – you’d be surprised)
  3. Keep the soil damp before using
  4. Wash your hands with soap and water before removing your mask.
  5. Store your potting mix in a cool, dry place, out of the sun.

Sufferers of Legionnaires’ disease experience an illness like a severe ‘flu’ infection that can develop up to 10 days after exposure to the bacteria.

Symptoms can include fever, chills, aching muscles and joints, a dry cough, headache (often severe), tiredness, loss of appetite and shortness of breath.

Early diagnoses and treatment with antibiotics will reduce the disease and shorten recovery time. As with all health issues protection and prevention maximises your time in the garden in peek condition ready to tackle all the spring chores.

Tip

If bagged soil products look dry when opened, it should be wet down before using. Always have your facemask on before opening and when watering.