Archive Article: 2000/03/10

10 March 2000




LATE-TILLERING to stem extension is a busy spray timing for cereals. Taking into account subtle differences in crop shape and size between these two timings when applying plant growth regulators could pay dividends in the final result.

Plant growth regulators applied to cereals at tillering must be geared to plants which are a lot smaller than those treated at later GS32 timings, advises applications specialist Tom Robinson of Novartis.

"At GS29, theres a lot less crop. So to get the maximum amount of spray on the crop use a medium to fine quality spray. Finer droplets help because they dont bounce back off the leaf after impact and, because theyre travelling slower, this also helps with droplet retention."

For GS32 PGR applications to boost stem strength of weak stemmed varieties like Consort or to reduce crop height of tall varieties, like Claire, the target is bigger, so growers have more flexibility with spray quality, he advises.

"At this timing you could go coarser and use Bubble Jets, which will help reduce drift, though conventional fan jet nozzles will deposit more on the plant. Twin fluid atomisers such as Airtec nozzles are also okay at both timings, but should be set for a finer spray at the earlier timing."

At the earlier application timing Novartis trials with pgr Moddus (trinexapas-ethyl) show water volumes can be reduced to 801/ha with both conventional and twin fluid atomiser nozzles. That helps improve work rates. Other products may vary, so check makers advice.

Optimum sprayer settings for the first pgr spray are conventional 110 degree fanjets (110-02 or -04) at 2-3 bars pressure and using a forward speed of 8-12km/h. That should deliver a spray volume of 100-200 litres/ha. For the GS32 application, use the same nozzles or equivalent sized air induction nozzles at 2-3 bars pressure to deliver a volume of 100-200 litres/ha at a forward speed at 8-12km/h. &#42


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