Hop Topic: Don’t be a pest!

Feb 11, 2014
A look at Integrated Pest Management

Bringing the best hops to the market takes an open mind. In this era of intense agriculture and science, sometimes it is better to take a minimal intervention approach to farming.

Integrated Pest Management (IPM) is a concept developed in the 1940’s as a way of dealing with pests that are not easily tackled by broad spectrum pesticides alone. Instead, it is a methodology of using biological, cultural and chemical controls in harmony with each other.

IPM has a fundamental reliance on biological control – using other native insects, such as mites and spiders to eat species of pests. We call these ‘beneficial’ species.

Cultural controls are farm practices that can impact on pest numbers. It includes elements such as tilling and irrigation, planting times and planting specific crops in the understory or in idled paddocks to attract or increase the number of beneficial species.

Chemical controls refer to the supporting role that targeted pesticides play in augmenting the IPM program. Broad spectrum, pyrethrum based sprays are not easily compatible with an IPM program. They are therefore not used on HPA farms, nor are the nasty group of chemicals known as organophosphates.

HPA has invested significantly in global research to identify the “softest” arachnicides available and accepted by our customers. All products are then extensively trialled before the collated data is provided to the APVMA for approval of use. This process takes a number of years.

In the gardens, two spotted mites are the major insect pest present and can significantly damage a crop very close to harvest. They only need 4 – 5 days to deteriorate cone colour and structure, cause stress to the plant (effecting future years vitality) and to seed a population of mites for over-wintering and re-emergence next year. Yes, they’re a very frustrating pest to manage.

You are probably thinking: Why not go organic? Unfortunately, our beneficial species are not quite able to ‘keep up’ on their own just yet. In certain circumstances we do still use pesticide, but we chose products for their minimal impact on beneficial species as much as for their efficacy in exterminating the two spotted mite. By being kind to our beneficial species, we use less pesticide year after year. HPA farms grow over 200ha of green manure cover crops every winter. These are helping increase the over wintering numbers of beneficial species from year to year, and as we learn more about the ‘cultural’ controls we can implement other practices on the farms. Fortunately, we’re also able to buy commercially grown populations of beneficial’s to help out when needed.

Every hop field is monitored weekly, from November through to harvest in March, to determine mite pressure and the level of beneficial control. Sprays are then limited to an optimum timing, in order to have maximum impact on the mites and selected so as to not harm the beneficial insects. In this way natural control is achieved well before harvest.

In the last 10 years, HPA has never returned a detectable pesticide residue in finished hop products. The limits of detection are much more stringent than the World Health Organisation guidelines for acceptable pesticide residues. We are very proud of this fact and believe it demonstrates our commitment to producing the finest quality hops by growing and processing them like the food ingredient they are.


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