Ear protection sprays likely to be of benefit

1 June 2001

Ear protection sprays likely to be of benefit

With yield prospects modest

at best is there any point

applying an ear protection

spray to most of this years

wheat crops? Our latest

baseline agronomy article

takes a closer look

WET, warm weather at ear emergence could justify a fungicide ear spray for many cereal crops, particularly those that could attract a quality premium.

The trouble is there is no way of predicting the weather risk until cereals come into flower, warns David Ellerton, of Essex-based agchem distributor and agronomy company ProCam.

That means growers have to treat the ear spray as a completely separate entity from other fungicide inputs. "Decisions need to be based on the weather conditions at the time."

The flag leaf spray will have provided protection against foliar diseases and can help prevent them from spreading onto the ear, but will have very little effect on specific ear diseases, says Dr Ellerton. "That is why a further spray is often needed."

Sooty moulds and fusarium are the two key disease targets for an ear spray. The ideal timing is once the ear is fully out, as the products used are protectants. "If you wait until flowering and beyond, control is likely to be diminished."

Product choice

If foliar diseases have been allowed to spread and get onto the ear, because the T2 spray was mistimed, Dr Ellerton suggests the use of a triazole and/or morpholine.

"If the rest of the plant is clean, then dont worry too much about foliar diseases and concentrate on the specific ear diseases with the ear spray."

For sooty mould, he highlights Amistar (azoxystrobin) as the best product. "Twist (trifloxystrobin) is also good and the triazoles have some effect.

"Charisma (famoxate + flusilazole), which is new to the market this season, also has good activity against sooty mould. Even old products containing carbendazim and dithiocarbamate can be useful."

But controlling sooty mould can allow fusarium to get a hold. "Creating a clean surface means that there is an opportunity for other diseases. And Amistar is very poor at controlling most of the fusarium species."

The main concern with fusarium is that some species are linked with mycotoxins. Proposed EU limits for certain mycotoxins in grain are likely to come into effect before too long, making product choice more important than before.

"If you are concerned about fusarium and mycotoxin levels, dont rely on Amistar alone for the ear spray," advises Dr Ellerton. "Alternatively, mix it with a fusarium-specific product."

His preferences for fusarium are Folicur (tebuconazole), Caramba (metconazole) or Charisma.

Economics

Yield responses of 1t/ha can be achieved from an ear spray alone in high-risk situations. "But theres a wide variation, and we cant say at this stage of the season what the response will be," says Dr Ellerton.

If a drought develops the risk of ear disease will be greatly reduced. By contrast a long grain filling period increases the risk and places more importance on the ear spray.

Dr Ellerton believes the cost of the ear spray should be viewed as risk protection. "Growers will have to spend £3-£8/acre. If there is a low risk they can go for a cheaper product. But where risk is high it is worth spending more." Adding a fusarium-specific product to Amistar does increase the price, he admits.

"If there are a lot of aphids around, you can include the insecticide and combine the two spraying operations. Theres an increased risk of sooty moulds where aphid populations are high, because of honeydew."

Apart from the yield effect, there are also quality concerns with ear disease. Grain shrivelling and discolouration are common. "It is usually worth applying an ear spray to a quality variety, or else markets will be limited. With feed varieties, it is more debatable whether the quality benefits alone are worthwhile."

Dr Ellerton says there could be very good premiums available this year. "Theres such a mixed bag of crops out there, from the very poor to the very good, that it is likely to be worth protecting a quality crop." &#42

Ear protection sprays are likely to be worthwhile if weather remains warm and wet, particularly in crops with premium potential, says David Ellerton of ProCam.

EARSPRAYS

&#8226 Wet, warm weather at ear emergence causes disease.

&#8226 Fusarium ear blight and sooty moulds the main disease targets.

&#8226 Amistar best for sooty mould.

&#8226 Mycotoxin risk from using Amistar alone.

&#8226 Spend £7-£20/ha.

&#8226 Protect quality crops because premiums will be high.