• TerrAvion TerrAvion
  • Jun 27
  • 2 min read

Use case: variable rate PGR applications

Plant Growth Regulator (PGR) applications are used in cotton to reduce vegetative growth and help maintain a manageable crop. PGRs help cotton plants direct their energy into making cotton instead of getting too tall. PGRs are also used by grass seed growers to control lodging in high vigor grass. Enlist_applicationIn both cases, PGRs, applied at a blanket rate, can achieve the desired result on some plants, but always at the expense of further stunting less mature plants. Variable rate applications provide the solution, enabling growers to apply PGRs where they will have productive results and withhold or limit applications where they will be detrimental.

Variable rate PGR applications in cotton

When applied to cotton, PGRs redirect plant growth from the vegetative leaves to boll production and as a result, can increase yield. But not all cotton plants will benefit from PGR applications. PGRs work best on healthy, vigorous cotton where conditions favor rank growth, but can limit the yield potential of lower performing plants. For this reason, there is great value in variable rate PGR applications for cotton growers.

Screenshot_177Variable rate PGR applications allow growers to place PGRs exactly where they are going to be most effective, enabling them to increase their yields by optimizing their inputs. For successful variable rate PGR programs, it is crucial for cotton growers to understand crop conditions in their individual fields and then make or withhold applications as conditions dictate. PGR timing generally is based on internode lengths. Growers can read the NDVI signatures of plants that have internodes at a certain length, highlight all of the plants that share those characteristics, and then target them for applications. The TerrAvion NDVI zoning tool makes it easy for growers to make management zone maps out of their imagery, which can then be exported as shapefiles. The only thing left to do is set the prescription rates.

Variable rate PGR applications in grass and grass seed

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Like in cotton, the intention of PGR applications in grass and grass seed is to stunt the growth of the crop. When the seed bank at the top of the grass gets too heavy, the plant can collapse on itself. Blanket rate PGR applications in grass seed accomplish one goal of controlling lodging in high vigor grass, but it is achieved at the expense of further stunting low vigor grass. For this reason, grass seed growers are turning to variable rate PGR applications. High-resolution NDVI imagery is capable of picking up even the faintest vigor variability in grass, and once dense and heavy grass is identified, it can be targeted for PGR applications. NDVI management zone maps enable growers to apply the highest rates of PGR to the heaviest grass and lower rates to lower vigor grass, controlling the weight of the heavy grass while allowing the low vigor grass to continue to grow to achieve its full yield potential.

Variable rate technologies offer profitable opportunities for cotton and grass seed growers, not only for PGR applications but also for the applications of nitrogen and other harvest aids. High-resolution NDVI imagery is a natural fit as a data solution for variable rate PGR applications. TerrAvion has worked with cotton growers around the country to tailor our OverView and mobile app features for PGR application use.

For more information on how to create NDVI management zone maps with TerrAvion, check out this video.