More than 40 growers attended a recent Farmacy trials demonstration day at Marsh Larder, Harleston in Norfolk, by kind permission of Lewis Partners.
Disease pressure at the demonstration site has been far higher latterly than during the dry conditions of last spring, said agronomist Dan Robinson, speaking at the event.
Wheat plots treated with a good robust standard fungicide and PGR programme looked healthy and full of potential, although there had been significant septoria infection of untreated wheat plots due to unsettled weather through June.
Due to the higher disease pressure he believed that yield benefits from fungicide treatments at the Harleston site were likely to significantly exceed last year.
"Even in the very low disease pressure last year, the mean untreated average yield over 30 wheat varieties was 11.22t/ha compared to treated at 12.83t/ha, that's still a 14.35 per cent response to fungicides which equates to 1.60t/ha."
Mr Robinson took the visitors through some exciting new chemistry options for the future, pointing out that the impending loss of chlorothalonil (CTL) poses a real challenge for disease control.
The plots offered a good insight into this, showing quite clearly that remaining available multi-sites such as Folpet, were not as effective as CTL. He added that further trials would look in more detail at timings and the impact on efficacy.
Looking at the variety demonstrations, Mr Robinson took the growers through a range of options for each sector. In the Group 1s, RGT Skyfall continues to dominate, and is the only milling wheat to offer orange wheat blossom midge (OWBM) resistance but he pointed out that priority must be given to it at harvest as it tends to sprout.
With interest around the Group 2 KWS Extase with its septoria rating of 8.1, Mr Robinson urged growers to ensure that they continued to use a sensible fungicide programme with the variety.
“Its not about cutting corners with fungicides on this variety, but using the resistance as a risk management strategy for example where spraying may be delayed. If not, the resistance will very quickly break down."
In the Group 3s, KWS Firefly was another that had done well against septoria and yellow rust this year, so could be a potential distilling option for growers with a local market, he said.
"RGT Gravity also continues to be a good choice with its high yield potential, and no major weaknesses."
Mr Robinson added a note of caution about the variety's unsuitability for early drilling, pointing out that it was best drilled in a mid-October slot.
In the all-important feed wheat sector, he highlighted LG Skyscraper as a stand-out performer so far this season. "Despite the conditions, it looked clean and stood well in our trials, so would be a really good fit for growers in this region."
Alongside high yield potential and good disease scores, Skyscraper's position as a soft Group 4, meant it also had distilling potential, he said.
Nutrition expert Rob Jewers followed on, encouraging growers to take regular tissue samples during the season.
"Results from across the Farmacy demonstration sites taken in April had shown levels of nutrients such as magnesium, potassium, zinc and boron were low."
He also underlined the value of carrying out a grain nutrient analysis. "This is a powerful indicator for nutrient levels at the end of the season, and to prepare for the next; it's particularly useful for the nitrogen: sulphur ratio, which last year was low at the Harleston site.
We also found deficiencies in phosphorus and magnesium, which we could address before the start of the season."
Seed rate work
Farmacy's technical director Dave Howard urged growers to look more closely at their seed rates as work that had been done by the firm indicated that higher seed rates were not always the optimum.
"Through the work in the Yield Enhancement Network, we know that achieving higher yields is all about having enough plants and ears per m2, and creating and maintaining that crop biomass to push for the higher yields" he said.
"However, we wanted to answer the question, if a variety is high tillering, is less seed needed for optimum plant ear counts and vice versa," he says.
Looking specifically at the impact of seed rates on varieties with different growth habits, a series of trials were established at Little Ponton in Lincolnshire.
In the trial, the wheat variety LG Sundance which has a high tiller retention growth habit was compared with the more standard tillering variety, KWS Siskin.
Both varieties were drilled at 4 different rates from 150-450 seeds/m2 in 100 seeds/m2 increments, and then the green area index and ear numbers were measured.
"We found that the tiller number for KWS Siskin was fairly static all the way up to 350 seeds/m2. This is most likely because as interplant competition increased, rooting was compromised and uptake of water and nutrients therefore limited – Little Ponton is a shallow light soil site.
"However at 450 seeds/m2 the significant increase in plants meant that even when tillers were lost due to competition for resources it still had enough plants there to make up for it. That said it equated to the same tiller number as 350 seeds/m2 of LG Sundance.
"LG Sundance responded well to higher seed rates and tiller number increased with each increase in seed rate performing best at 450 seeds/m2 producing more ears and a greater green area index.
"Interestingly, as the dry weather took hold, its genetic tillering potential came to the fore and showed very little loss of tillers between March and April by comparison to KWS Siskin.
"Sites where access to water or nutrition can be challenging find it hard to support high plant populations as competition for resources outweighs plant potential.
"This confirms much about what we already thought; in order to get the optimum ear counts and crop biomass, and eventually higher yields, variable seed rates cannot be calculated on soil type alone," concluded Mr Howard.