Long term commitment to top quality Brussels sprouts

Image (L to R): John and Darren make a closer inspection of one of the Brussels sprout crops on the Cranwell’s Nairne property.

John and his wife, Julie, together with his brother, Robert, and his wife, Joadi, and their children, Erin and Josh, grow about 58 hectares of Brussels sprouts annually over two properties at Nairne and Langhorne Creek.

Trading today as AE Cranwell & Sons, the family’s market gardening originally commenced with John and Robert’s great grandfather, William Henry, in Ashton, nearer to Adelaide.

“They were growing sprouts in the ‘40s, but they were also growing everything else, including cherries, cabbages, lettuces, strawberries and even gooseberries,’’ John said.

“We started growing sprouts exclusively from about 1970 and we grew leeks for a while, but then we were all sprouts again from about 2005.’’

They supply all distribution centres of the major retailers across Australia, as well as wholesale markets.

The Brussels sprouts are grown on a three-year land rotation, with 15 different varieties of seedlings from Boomaroo Nurseries transplanted from July to January and harvested from January to August.

John said they had to successfully manage the crops for up to seven months.

“They are a long lived crop – and it is a vegetable so you have to look after it,’’ John said.

He said insects had become an increasing factor since resistance to organophosphate and synthetic pyrethroid insecticides became an issue in the ‘90s, and required constant monitoring. Greater use of more targeted products today, rather than broad spectrum, had also given rise to secondary pests.

Diamondback moth, aphids and thrips are some of the major insects, with massive flights of diamondback moth occurring as canola crops dry-off in broadacre areas.

Image: (L to R): Darren and John look over some of the Brussels sprouts seedlings from Boomaroo Nurseries.

The Cranwells have long been strong advocates of integrated pest management (IPM) and release parasites against diamondback moth and aphids sourced from James Altman and his team at Biological Services in Loxton.

“We release ‘beneficials’ weekly for the first few months until we get on to chemistry that’s not so soft on them,’’ John said.

He said they were also “sticklers’’ for rotating chemistry, especially not using two chemical groups at once.

“We are fortunate that we don’t have close neighbours growing the same crops, so our chemical rotation strategy works very well.’’

“We like to use Group 28 (insecticides) at periods of peak pressure. With two different properties and multiple blocks, the peak pressure can be at different times and so the products are used at different times, helping maintain the rotation strategy,’’ John said.

DiPel® biological insecticide, containing the bacteria Bacillus thuringiensis (Bt), is used when insect pressure is light.

The systemic and IPM-friendly Group 23 insecticide, Movento®, has been used against aphids and this year, following its registration for control of diamondback moth in brassica vegetables, it was used as an aphid and diamondback moth spray.

“We are using Movento after the Bt when the pressure is not that great and the diamondback moth larvae is at an early instar stage – and we have been very happy with it,’’ John said.

Different to most systemic insecticides, which, after leaf uptake are mainly translocated upwards in the plant’s xylem along with water and nutrients, Movento, from Bayer, is translocated in the plant’s phloem as well as xylem, resulting in transportation upwards and downwards to plant parts. It can better control sucking pests hiding on covered inner leaves than other insecticides, as well as populations that may have developed resistance to existing registered products.

Image (L to R): Bayer Commercial Sales Representative Darren Alexander discusses sprayer set up for the application of Movento insecticide with SA Brussels sprouts grower John Cranwell, Nairne and Langhorne Creek.

In addition to aphids and diamondback moth, Movento offers control of silverleaf whitefly. Other than vegetable crops, it can also be used in stone fruit, mangoes, grapes, pome fruit and cotton for control or suppression of a range of pests.

It is highly compatible for tank mixing with other products and is “soft’’ on most beneficial species when used as directed, including parasitoids, syrphid flies, lacewings, predatory midges, ladybird beetles, predatory bugs and earwigs.

“We do two applications of Movento in a row no matter what, with emulsifiable oil and 500-1000 L/ha water rates,’’ John said.

“It has a unique form of action and is so soft on ‘beneficials’. Our IPM specialist was here and said, ‘we are not going to release any more – you have thousands of them’.

“Movento is not quick acting – growers need to read the label and be aware of that. And the rate for diamondback moth and aphids is different. But it’s a good product – it kills them.’’

Bayer Commercial Sales Representative Darren Alexander said for diamondback moth, the application rate needed to be increased to 400 mL/ha.

John said later, any surviving insects were knocked out by other insecticides including Avatar®, Proclaim® and Success® Neo insecticides.

“We spray every 10-14 days. We use all major, different chemical groups in a calculated strategy to prevent resistance and going from the softest to the hardest to fit in with our IPM program.’’

“The parasites get the bugs that the sprays don’t get, or that are resistant.’’

He said the program helped to achieve the final objective of producing clean, green and hard Brussels sprouts that were free of blemish and would last in the fridge for at least two weeks.