| |
Don’t let fungicide spray intervals slip
Date added: 21/05/09 |
Wheat growers should keep their fungicide spray intervals between T1 and T2 to no more than four weeks, even when disease levels are low, advise ProCam.
According to the company’s 4cast data, doing so can produce an additional 0.3 tonnes/ha as well as protecting the flag leaf and ear from a range of yield and quality-damaging diseases, says group agronomist Nick Myers.
“Some growers may be tempted to lengthen the interval between T1 and T2 treatments in response to this year’s low disease pressure,” he warns.
“It has been a much drier spring so far and consequently disease levels are generally low. Some growers missed out on a T0, starting their programme with a T1 spray and are just ready to apply a T2. Others managed to apply a T0 and T1, with this latter spray going on at the end of April.
“If the weather turns wet, Septoria could easily take a hold and then growers could be struggling to keep on top of the disease. This is why it is so crucial to keep the interval between T1 and T2 tight, certainly no more than four weeks.”
Nick points out that the latent period for Septoria, which is the time it takes for the disease to infect the crop and symptoms to be seen, is normally 4 to 6 weeks in winter/early spring, but it can be as short as ten days under warmer conditions around flag leaf emergence.
“If you get delayed for any reason, fungicides won’t have sufficient kick-back to cope with the shorter latent period.”
T2 is the key yield building timing and even with low disease pressure and some crops with lower yield potential this year, it remains the most important fungicide treatment, he points out.
“You must always apply a good dose of a triazole, at least three-quarter rate, preferably with a strobilurin, at least third rate, at flag leaf emergence.”
Including a strobilurin at T2 timing typically resulted in an extra 0.3-4 t/ha yield compared to triazole only treatments. In 2007 when rusts were a disease threat responses were around 0.7 t/ha on average, he explains.
“The T2 timing is a key timing for strobilurin responses. In addition to their disease effect they have a significant role in maintaining green leaf area through the grain fill period.”
The timing of any ear (T3) fungicides also needs careful consideration and T3 fungicide applications should made according to crop growth stage, rather than a set interval, Nick Myers says.
“The T3 needs to be applied just before or at flowering to be effective against Fusarium and suppress mycotoxin production. This often means an interval of between 7 and 10 days from T2.
“But there is no set spray interval per se - you just need to be sure that the ear is well protected. Ear washes that are applied after flowering won’t be effective against Fusarium.”
Ends.
PRM215
21st May 2009
For further information please contact Nick Myers, ProCam Ltd., Royston, Herts. Telephone: 01763 261592
Issued by Philip Hainey, Proterra Ltd., Stamford, Lincs. Telephone: 01780 756299 |
|
