By Rhiann Jakubowski
The Lake Erie region is finally showing signs of spring! As tree canopies begin to fill in with green buds, we are reminded that the grape vines are soon to follow. With a historical average bud-break date of May 5th, phenological signs are pointing to 2017 being about one week ahead of schedule. While we are eager to sink our teeth into another growing season, the project team at CLEREL is working hard to ensure all sensors, dataloggers, and equipment are ready to collect valuable early-season information.
Jackie Dresser and I have been working to create a “sensing schedule”, which includes a work plan of deployment of NDVI and soil sensors (image 1), shoot thinning and fruit thinning machines, and field data collection teams. Our most important objective is to make certain that NDVI data is collected at the 3-5” shoot stage in all test vineyards in the Lake Erie region. This early-season scan is a vital resource when making shoot thinning decisions because it is effectively the grower’s “first-look” at the growth patterns of their vineyard this season.
Immediately following NDVI data collection using the CropCircle sensors, I will process and analyze the data to give an overview of the patterns of shoot density in the vineyard blocks. From there, a decision will be made along with the grower/manager of the vineyards regarding variable rate shoot thinning (image 2).
For example, in the zone with the highest NDVI values, what percentage of shoots am I looking to remove using my shoot thinner? What about in the other vigor zones? Do I want to leave some zones unthinned? In the Lake Erie region where more buds are often left during dormant season pruning, shoot thinning is a practice for growers to adjust their crops after the threat of spring frost has passed.
Once the grower/manager has made a decision about the levels of shoot removal they desire, I will input that information into the computer software that will communicate with the shoot thinner to change speeds as the tractor moves along vineyard rows. We will set up control rows as well as check plots throughout the vineyard to measure the effect of the variable rate management on shoot removal by counting shoots before and after shoot thinning. We will continue to monitor the vineyard canopy growth through NDVI scans several times throughout the growing season. The field team will also collect berry samples in the plots from veraison to harvest to track ripening and model berry characteristics in treatment and control sections.