Wheat School: Timing growth regulators for winter wheat


As tillering winter wheat moves into stem elongation it’s time to assess the lodging potential of the crop and determine whether a plant growth regulator (PGR) should be applied.

On this episode of RealAgriculture’s Wheat School, Syngenta agronomic service representative Marijka Vanderlaan offers tips on identifying plant growth stages and how plant growth can be used to time growth regulator application timing.

Quite simply, Vanderlaan says PGRs are all about preventing and reducing lodging risk. They also allow growers to more intensely manage their crop by using higher nitrogen rates to drive yield, for example, while helping plants build a stronger base and stand through to harvest.

Optimum application timing for PGRs is from growth stage 30 to 32. In the video, Vanderlaan demonstrated how growers can cut plant stems to determine the growth stage of the crop. When the head is one centimetre above the base, the plant has reached growth stage 30; when one node is detected it has reached growth stage 31; and two nodes indicate growth stage 32.

Vanderlaan says there is limited Ontario research on how fast a wheat plant progresses through growth stages, but, in general, each stage requires about 90 to 120 Growing Degree Days. Looking at the forecast for southern Ontario for the first weeks of May, she estimates that growers have about a two-week window for optimum application. She notes, however, that PGRs can be applied up to growth stage 37 and still deliver strong performance.

Spring can be a busy time for wheat growers who need to apply weed control, fungicides and PGRs. Vanderlaan says if time gets tight, applying a three-way tank mix is an option, but growers should be using a minimum water volume of 20 gallons. She adds, however, if winter annuals like chick weed and dandelion are gaining a foothold in the field growers need to get their weed control down first. The PGR and fungicide can then be combined and targeted to the growth stage 30 – 32 window.

Click here for more Wheat School videos.

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