Dissect to gain pgr timing edge
Dissect to gain pgr timing edge
DO-IT-YOURSELF checks on wheat development could be a big help to growers planning pgrs.
Collect 10 typical plants across each field and peel back the leaves on the main tiller to precisely identify the growth stage, advises Norfolk-based independent consultant Margaret Appleyard. "You dont even need a knife, fingernails will do."
If four out of five plants are at the same stage that can be taken as a fair representation of development across the field. If in doubt, do more.
Computer predictions or guesses based on calendar date and variety are no substitute for field-walking, she says.
That is echoed by Nottingham Universitys Pete Berry who says many growers fail to understand the factors causing lodging, leading to poorly targeted pgr use.
"Plant growth regulators are used on about 80% of wheat crops at a cost of about £15m/year, yet the frequency of bad lodging years is not diminishing."
Understanding the point of failure is the key to improving control. Leaning rather than buckled stems are mainly to blame, caused by root lodging. "Failure to recognise this is why control is not as good as it should be," he says.
Reduce height
Root lodging is related to anchorage strength and plant leverage, but evidence that pgrs can increase rooting is limited, he stresses. "The best way to avoid root lodging is to use a mid-season pgr to reduce crop height."
For early drilled, thicker crops BASFs John Peck suggests a GS30-32 application of 0.75-2.5 litre/ha of New 5C Cycocel (chlormequat + choline chloride) with the T1 fungicide to shorten lower internodes, followed by Terpal (2-choroethylphosphonic acid + mepiquat chloride) post GS32.
"Growers are wary of mid-season pgrs, but a lot of lodging occurs because they assume early chlormequat is enough," he says.
The follow-up treatment is especially important in winter and spring barley where crops tend to "bounce-back" from early pgr applications with longer, weaker internodes if left untreated, says Mr Peck.
Backward and thin winter wheats should receive nitrogen first at 80kg/ha when the crop has at least three leaves, then a 1.75-2.5 litre/ha Cycocel application to boost tillering and rooting.
"The high level of nitrogen is needed because of the limited root system – you need a high concentration of nutrient in the soil." *