Biological move adds flexibility for effective strawberry protection

In another bonus, adding an extra mode of action into a rotation of fungicides used against disease is also further helping to prevent disease resistance and maintain the effectiveness of the fungicides.

 

Ti Strawberries is a vertically integrated growing, marketing and exporting operation, producing around 1500 tonnes of strawberries annually. They are sold to domestic markets as well as to the Middle East, throughout South East Asia and New Zealand.

 

The company’s Jamie Michael said in some years, it can be raining on 50 percent of picking days from late April to November, heightening disease risk. Consequently, crop protection tunnels are used over crops, but they also cause disease issues due to the humidity.

 

“Disease is a constant concern through the winter months, particularly botrytis and powdery mildew,’’ Jamie said.

 

“If botrytis is controlled well, you won’t see it coming through. If not, you can have 50 percent loss on any particular pick.

 

“The reason botrytis is a big issue is it’s also not just the crop losses. It’s then the grading, the fact you are paying to pick fruit you are now going to throw out and the control required moving forward. It takes three to four weeks to get back under control. In a season that’s five months long, that’s 20 percent of your production period.

 

“On top of that, you’ve got the labour required to clean up out in the field and all of the labour to produce something you can’t pack.’’ 

 

 The biological foliar fungicide, Serenade® Opti, from Bayer, was introduced and added to the product rotation this season on advice from Des May with David Grays Aglink.

 

“Des is very proactive. He’s always introducing us to new products that can help us to continue to improve and move forward,’’ Jamie said.

 

“Des thought it would be a good fit with the tools we are currently using and it has certainly fitted quite well,’’ Jamie said.

 

Containing the unique properties of the QST713 strain of Bacillus amyloliquefaciens (also known as Bacillus subtilis) bacteria, Serenade Opti is a formulated combination of spores and fungicidally active compounds produced during fermentation. It acts as a fungicide by preventing spore germination and germ tube elongation and penetration, and as a bactericide by direct contact activity. The product also has the ability to activate the plant’s natural disease resistance mechanisms.

 

 

In addition to its use in strawberries, Serenade Opti also controls botrytis in grapevines and suppresses bacterial spot in tomatoes, capsicums and chillies, as well as stem end rot and anthracnose in avocado, mango and other tropical fruit crops. It is compatible with many commonly used insecticides, fungicides and other treatments, plus Serenade Opti is registered as an organically-certified input by ACO and OMRI, allowing its use in organic farming systems.

 

“The number one advantage with Serenade Opti is there’s no withholding period. Our strawberries are picked every two to three days, so the timing of sprays when you have withholding periods to deal with can be a challenge,’’ Jamie said.

 

“The fact it’s biological is another big advantage because everyone is looking for fruit produced with as few chemicals as possible, and in some markets it’s a good selling point.’’

 

 

 “We clearly saw some effectiveness and that gave us the confidence to keep using it,’’ Jamie said.

 

“We tried it mid season and then ran it on rotation. We normally apply a fungicide once a week, so in rotation with the other fungicides, it was about three applications a month apart.’’

 

Products are applied using a 32-metre Hardi, air-assisted sprayer. The Serenade Opti was applied at 150 g/100 L of water as part of a total solution application of 1000 L/ha.

 

“We consider rotating chemicals to be really important against disease resistance. There’s only a small number of tools that we have against most diseases, so it’s important to get the most life out them and the only real way to do that is through rotation,’’ Jamie said.

 

“We have seen resistance before to other chemicals for other diseases and once you have a product that’s effective, you want to continue using it and that’s always part of our mindset when applying chemicals.’’

 

He said they were happy with the disease protection Serenade Opti was providing.

 

“The mark of a good treatment program is not having a problem at the end of it and since we included Serenade Opti, we haven’t had a botrytis issue.’’

 

“We have a program that’s a bit more weighted to a biological program now and it’s working well.’’

 

Des said biological fungicides were becoming more strongly considered in growers’ disease management programs, particularly for their major benefit of no withholding periods.

 

In addition to naturally occurring beneficial insects at the farm, Ti Strawberries introduced persimilis predatory mites into the crop this year to help control two-spotted spider mite and Jamie said the Serenade Opti suited this integrated pest management program (IPM). When used as directed, it is soft on most beneficial insect species, including predatory ladybird beetles, green lacewings, parasitic wasps and predatory mites. Importantly, the predatory bug, Orius, which is used extensively in strawberries, has since been added to this list following independent research conducted by cesar. 

 

“We always favour biological controls within our IPM program. It’s important not just for consumer palatability, but also for export markets where we have to be really conscious of MRLs (maximum residue limits). So any biological products that come along, and that are effective, are a definite step forward for the industry.’’

 

“We know consumers are looking for a cleaner and greener product, and Serenade Opti fits really nicely into that and into our IPM, so we intend to include it in our program going forward.

 

“It’s great to introduce an effective new biological product to rotate with our traditional chemistry.’’