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DIFFICULT EARLY SPRAYS MAKE T2 APPLICATIONS CRITICAL
Date added: 05/05/06 |
Upcoming T2 sprays will be the most critical of the year following compromised T0 and T1 applications across much of the country, warns ProCam technical agronomist Steve Wolff.
And with crops now well forward because of high residual soil nitrogens and the mild winter, there’s a real risk of a Septoria explosion if growers do not plan their spray programmes carefully for the rest of the season.
“Many growers have had to make fairly robust T1 sprays to make up for missed T0 applications whilst others got T0 sprays on late and are now thinking of missing T1 completely, hoping to make it up at T2,” he explains.
“If you’ve managed to make T0 and T1 sprays you must stick to a 4 spray programme but if your early sprays have been compromised you must make an appropriate T2 spray ensuring it is no more than 4 weeks after the last spray you have applied.”
ProCam 4cast data clearly shows the difference between following a structured four spray schedule with applications made at T0, T1, T2 and T3 and a more reactive three spray programme can be as much as 3.5 t/ha – producing a gross margin advantage of £234/ha.
Furthermore, 4cast data from the last 5 years suggests that every time a spray is missed from a model four spray programme, a yield loss of around 0.3t/ha results.
“Once Septoria gets established, there is little you can do to stop it and the most worrying feature is the speed at which the disease can develop. You may think all is well one day and plan on delaying or even missing a spray and then one week later you’re dealing with a full blown problem,” Steve Wolff says.
“The maximum 4 week timing between sprays is critical the way this year is shaping up. Leave it longer and you’ll be applying much higher rates of triazoles than are necessary. Interval is definitely more critical this year than the precise stage of growth.”
Producers must not forget about growth regulators because of the well advanced nature of many crops.
Although disease threat is high, weed levels seem to be low showing autumn herbicide programmes were by-and-large successful. Cleavers are, however, prevalent in some areas.
Early indications suggest rhynchosporium is the disease to look out for in Winter Barley and Phoma canker, sclerotinia and alternaria are the potential threats in Oilseed Rape.
“This is a difficult year for disease control,” he says. “If you have any doubts whatsoever about timings and product choice, you must talk to your agronomist as mistakes made now will be difficult and costly to rectify later.” |
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