Dont let fungicide yield benefits go begging
Dont let fungicide yield benefits go begging
By Charles Abel
DONT cut your own throat by missing out on significant yield benefits from the latest fungicide chemistry, warns BASF.
Moving from a first generation strob-based programme to one based on its recently launched second-generation strobilurin, pyraclostrobin, could add £16/ha to crop margins, the German manufacturer suggests.
"Pyraclostrobin (as in Opera and other branded formulations) offers the same stepwise benefit that we saw from Landmark over triazoles," says business develop-ment manager Steve Waterhouse.
That was shown in the typical disease response season of 2000. "A Landmark-based programme gave a 0.6t/ha yield response over an Opus programme, and an Opera-based programme gave another 0.6t/ha on top of that."
Margin over chemical cost responded accordingly, rising from £143/ha with Opus, to £170/ha with a first generation strob to £186/ha with Opera. That assumes a grain price of £63/t and typical product prices of £37.26/litre for Opera, £38 for Landmark, £33 for Amistar, £18 for Twist and £23 for Opus.
"The risk is that agronomists are driving down product use, because farmers are saying they dont want to spend," says Mr Waterhouse. "But the facts show they should make the extra investment."
NIAB principal pathologist Rosemary Bayles agrees, stressing that last years 0.14t/ha average yield response from Opera over Landmark was an anomaly, caused by exceptionally low disease levels.
"We are often guilty of farming on last years results and I think there is a risk of that happening here," warns Mr Waterhouse.
Low grain price should have relatively little impact on product use, he says. Taking an average yield response over the past five years, of about 3.5t/ha over untreated, a Landmark-based programme gives an average margin over chemical cost of £166/ha, assuming a grain price of £63/t and a programme cost of £48/ha, he says.
A further £10/t fall in grain price cuts the margin over chemical cost by £40/ha, but still leaves a £126/ha boost over untreated, he explains. "That makes the strob fungicide a prime driver of profitability on the farm."
Despite dry conditions earlier this spring disease risk remains high, adds Dr Bayles. "There is plenty of inoculum about, so conditions over the next week or so will be important."
Variety mix worries
The mix of varieties being grown could also have a crucial bearing on disease pressure. Unlike the generally good resistance ratings for yellow rust, Septoria resistance is weak. No popular variety scores an eight or nine for resistance, just 30% of plantings manage a seven and the rest are more susceptible. "Nationally there will be a lot of inoculum," Dr Bayles predicts.
But NIAB data shows Operas yield boost over earlier strobilurin fungicides is consistent across varieties, adding an average 0.62t/ha in the high Septoria year of 2000.
For growers looking to move to a two-spray strategy this season following a late T1, Operas superior kickback activity could allow a later flag leaf timing, so persistence covers the T3 ear spray too, notes Mr Waterhouse.
Trials show pyraclostrobin offers significantly more kickback than top kickback triazole Opus, which itself outperforms picoxystrobin (Acanto) and trifloxystrobin (Twist). It also lasts at least as long as the competition, he claims.
Greater curative activity may also be needed where low rate or early T1 sprays run out of steam too soon. Indeed, many farmers may have given-up the chance for a two-spray programme by using too little product at T1, so compromising the flag-leaf spray timing, he notes.
For best yield responses keep doses up, he adds. A £10/ha saving on fungicide does little to cut production costs, but could risk worthwhile yield benefits.
lFarm-gate strobilurin prices are already down on last years, mainly due to limited sales during the slack T1 spray window, admits product manager Tony Grayburn. Although the crop area is up, rates have been cut hard, with some growers even using triazole-only programmes. *
Recent rains have added to Septoria risk, so dont let tight budgets stop you from reaping the benefits of new strobilurins, say (left-right) Steve Waterhouse and Rachel Horton of BASF and Rosemary Bayles of NIAB.
• Good yield potential.
• Beware lightweight T1.
• High Septoria risk.
• Good margin over cost.
• Keep rates up for best responses.
Infection confusion
Dont be confused by some relatively Septoria-resistant varieties showing apparently more infection than more susceptible ones, says NIAB principal plant pathologist Rosemary Bayles. "High levels in Claire now will be overtaken by its resistance. Varietal infection levels can look very similar, but it is really from here on that resistance starts to show."