David Fuller is working his two Agrifac sprayers hard and combined with the latest spraying tech, four weather stations and a Basis-qualified team, he is managing to stay on top of wheat disease.

Hitting the key growth stages is no mean feat given that McGregor Farms manages 1,700ha of feed wheat across 15 farms stretching from the coast up the Tweed Valley, within a 15 mile radius of Coldstream Mains.

Added into this mix is that nine different varieties are grown with differing characteristics and disease scores. It’s a challenge that is getting harder too, with the climate becoming wetter and with spray days seemingly at a premium.

See also: How to control yellow rust in wheat without epoxiconazole

Fungicide programmes are largely preventative, given the lack of curative firepower in today’s fungicide armoury.

Therefore, timing is critical for keeping on top of the two main threats in this part of the UK – septoria and fusarium.

“We work very hard to hit the right growth stages with our fungicides,” says Mr Fuller.

So how do Mr Fuller and assistant arable manager Tom Hoggan achieve this?

Plant dissection

To ensure they hit the correct growth stages, both Mr Fuller and Mr Hoggan, who are Basis qualified, invest time in walking crops, rather than going by calendar dates.

Especially given the range of varieties and locations, which can see 10 days difference in timings.

The timing of the T1 fungicide is critical to the success of the overall fungicide programme in winter wheat and the aim is to ensure leaf 3 is adequately protected, says Bayer’s commercial technical manager for southern Scotland, Craig Simpson.

“The target is to spray when there is 75% emergence of leaf 3 on the main stem.”

Sprayer capacity

With spray days at a premium, having sufficient sprayer capacity is key to capitalising on the opportunities.

Mr Fuller points to local weather data showing nearly 150mm more rain than in the late 1980s and 1990s. And there are longer spells of weather types.

• 1989-98 – 611.85 mm
• 1999-08 – 745.10 mm
• 2009-18 – 755.30 mm

Therefore, they run two 36m Agrifac sprayers with 5,000 litre capacities, which equates to 50ha a load running at 100litres/ha.  

Mr Fuller admits he runs them hard, as they are also used to apply liquid fertiliser across the 3,400ha of arable cropping, of which 1,700ha is wheat.

They can average 160-180ha a day, depending on conditions, as they often get part days.

Generally, they can get round all the wheat in five to six days. To help with logistics, wheat is grown in blocks of the same variety to save on part loads.

© David Fuller

Pulse width modulation

The machines are fitted with pulse width modulation (PWM) and Mr Hoggan explains that it uses electrically actuated nozzles rather than a diaphragm valve to control the pressure and flow rate.

A conventional spray system is directly reliant on forward speed to increase pressure and thus control the overall flow rate.

However, a PWM system has the ability to electrically change flow rates at individual nozzles, where it maintains the same pressure no matter how often the individual nozzle solenoids are opened and closed.

“Each nozzle opens (pulses) up to 100 times a second and the faster you go forward, the more it pulses,” says Mr Fuller.

The upshot is that spray quality, pattern and flow rate remain constant, regardless of speed. One advantage is that operators can push on a little faster on good spraying days.

Another key advantage is that the system can compensate for corners, where the booms can have different forward speeds, for more accurate dosing.

“It means you don’t over or under apply when sweeping around a turn,” says Mr Fuller.

For example, sweeping round bends sometimes saw bromes survive herbicide applications.

“We’ve eliminated these underdosing areas with herbicides, so perhaps it’s the same with fungicides and disease?”

The pulse width modulation system is also more forgiving. “You can drop the pressure to 2 bar and create coarser droplets less prone to drift in sub-optimal conditions”

Weather stations

McGregor Farms has also invested in four on-farm weather stations, to better plan activities such as spraying.

Conditions can vary for the different locations. For example, it may be too windy to spray on the block of land near the coast or on the hills, but conditions in the Tweed valley are calmer.

“If too windy in one place, you can move to another where it is less windy,” says Mr Hoggan.  

Contractor top-up

Finally, it can still sometimes be a struggle to keep up at certain points and hit the key timings. Rather than compromise timings, Mr Fuller is prepared to use a contractor to help out.

“For example, last year we got one in to apply Broadway Star (florasulam + pyroxsulam) in the wheat,” he says.

Fungicide strategy

Last season, David Fuller’s disease strategy helped deliver consistently high yields, with the farm’s wheat crops having a five-year average of 10.05t/ha.

© David Fuller

This was despite the challenging conditions, which saw 23 frosts last April. “There was not a lot of spraying happening that month,” he recalls.

Spray intervals were kept tight, with three weeks between T1 and T2 and the T2 to T3 interval was also two-and-a-half to three weeks.

He adds that the T3 timing is essential, as there can be a lot of fusarium pressure in the north.

His fungicide approach is based on using two SDHIs and T0s. In 2021 On average, he spent £85/ha on fungicides (including two SDHIs and T0s).

But this year with the price rises, new chemistry and the addition of folpet it will be closer to £115/ha. 

For the past two seasons, he has used Ascra (bixafen + fluopyram + prothioconazole) at T1 and Revystar (fluxapyroxad + mefentrifluconazole) at T2.

Looking at this season, he is planning to try the new site of action fungicide Univoq (fenpicoxamid + prothioconazole) at the T2.

This season, his current plan is:

• T0 – tebuconazole
• T1 –  Ascra and possibly some Revystar. He may also add the multisite folpet.
• T2 – Revystar or Univoq
• T3 – tebuconazole

Programmes are tailored to varieties. For example, dirtier varieties with a septoria rating of 5 or less (such as Skyscraper and Jackal) also received the biostimulant Scyon along with tebuconazole at T0.