VegNET Gippsland Regional Update

Participants are briefed on what to look for, from pest populations to signs of beneficial insects and crop health indicators. Armed with tools like hand lenses and vacuum sampler (a leaf blower with stocking attachment) attendees venture into the field to uncover what’s really happening on the ground.

One key area of focus is pest identification and lifecycle monitoring. Growers learn to distinguish between harmful pests and beneficial species that act as natural predators or parasitoids. For example, while aphids might catch the eye, spotting a parasitic wasp laying eggs within an aphid colony can completely change the need for chemical control.

Damage assessment is another critical skill taught during these walk-throughs. Participants observe symptoms like leaf discoloration, chewing damage, or frass (pest droppings) and discuss whether intervention is needed. Understanding economic thresholds—the point at which pest damage justifies the cost of control—is an eye-opening concept for many growers.

Real-world solutions in action

The beauty of IPM walk-throughs is their real-world application. Participants can see how different strategies work together:

• Biological controls: Releasing predatory mites, introducing ladybirds.
• Cultural practices: Implementing crop rotations, conserving habitat for beneficial insects or intercropping to disrupt pest cycles.
• Targeted chemical use: Choosing pesticides carefully, respecting natural enemies, and preventing resistance.

Collaboration and knowledge sharing

These events foster a collaborative environment where participants can share their own experiences and learn from others. It’s not uncommon for a grower to offer a creative solution to a pest problem, such as using companion planting to deter specific pests or trialling pheromone traps for early pest detection.

The need for the IPM crop walk-throughs for our Gippsland growers was identified early in 2024 with an IPM presentation by Dr Paul Horne, facilitated by VegNET and Food & Fibre Gippsland. Three local growers were interested in having a more tailored assessment on their crops.

Agronomists and extension officers often lead these walkthroughs, providing expert guidance while ensuring the information is accessible and practical. Tools like monitoring apps and pest forecasting models are introduced, equipping growers with technology to enhance their IPM practices.

What was found in Gippsland

We visited three different farms on 12 and 13 November 2024 with Paul Horne and Rebecca Addison from IPM Technologies. Some of the crops doubled up, so the notes here describe what was observed and discussed on a crop-by-crop basis.

Rocketbrassicas

We showed the participants different methods of monitoring populations of both pests and beneficial species of insects and mites. At that time there were extremely high numbers of diamondback moth (DBM) adults, many eggs and in some paddocks lots of grubs. Some of the discussion points:

• Leaving the crop to flower for use as nectar source risks building up DBM populations on your farm if they are not managed.
• Suction sampling can be a simple monitoring tool to find small grubs, much easier than searching through yourself; this method is helpful for determining if insecticides have worked or not. For example, if the sample collects a mix of small and large grubs on a recently sprayed crop, it can provide an indication of insecticide failure or only partial impact.
• Suction sampling will also provide a more precise idea of how many adults are about.
• Direct searching is necessary for DBM eggs.

We discussed pesticide options and resistance issues. A key point was the impact of pesticides on beneficial species and not just on the pests. Diadegma wasps are parasitoids that are commercially available to help with DBM control, although this is more suited to broccoli and cauliflower.

Spring onions

We found onion maggots causing losses by chewing plants in the soil.

We discussed how planting rotations can affect control as well as insecticide options. Sequential plantings would favour the movement of onion maggot adults into new planting. Moving new plantings further away from each other would help reduce this risk.

Corn

Dr Paul Horne from IPM technologies inspecting Spring onion for pests.

There was damage present in the crop that could have been caused by several different pests, including cutworm, earwigs and slugs.

• We discussed how cutworm grubs can survive some tillage, so could potentially have been there in the previous crop. The grubs were about 3cm long, so possibly 3rd or 4th instar.
• Slugs can also cause some similar damage; we discussed slug bait selection and rates. It is important to know your slug pressure before applying baits. This is most simply done by placing monitoring tiles or an old square of carpet etc. in the field and leaving it for a few days to a week. There needs to be moisture around, but the slugs (and earwigs) will seek refuge under the tile in the daylight hours.
• We discussed how to select appropriate baits and whether or not expensive baits were necessary.
• There was a high number of Heliothis eggs on the earliest planting and these were a few days from hatching. We discussed pesticide options, including virus and bacterial insecticides.

Spinach

The main concern for spinach was leafminer fly. We found lots of leaf holes but very few leafminer trails in the leaves. Using the vacuum sampler, we found one adult fly. The main beneficial species that will help control leafminer fly is a wasp.

We discussed the impact of various insecticides on the pest and its natural enemies, in addition to the options for non-chemical methods to encourage biological control.

Join the movement

If you’re looking to refine your pest management strategies, attending an IPM crop walk-through is a must. These events combine practical learning with expert advice, offering a unique opportunity to see IPM principles in action. By embracing IPM, we not only protect our crops but also contribute to a healthier environment for future generations.

FIND OUT MORE
Please contact Amanda Gould on 0474 500 380 or email amanda.gould@foodfibregippsland.com.au