WITH measurements starting October 1, 2016, the 2016/17 winter rains have been characterized by some gangbusters events. As reported by the LA Times, a 122-year precipitation record has just been set in the northern Sierra - edging out the 1982-83 season - and the breaking of more records appears imminent in other areas of the state with a wet beginning to this week.
As per usual, the rainfall totals have resembled a crazy-quilt up and down the West Coast. Sonoma and Napa Counties (Map 1) , western SLO (Map 2), and Santa Cruz / Monterey (Map 3), took it on the head - with totals exceeding 200 and even 300% of their long-term precipitation averages.
Meanwhile, the Pacific Northwest had a healthy rain year (Map 4), with much of the region receiving 110 to 130%+ of the normal amounts, and Santa Barbara County experiencing a relatively normal precipitation year (Map 2). All maps courtesy of the California-Nevada and Northwest River Forecast Centers.
The soggy season saw a lot of growers delaying pruning until conditions grew sufficiently dry to avoid encouraging the spread of disease, only to face the challenges involved in getting pruning crews into flooded blocks. Fortunately, many of the precipitation events of the season were short and intense, often allowing standing water to drain off in a matter of days.
This year's bud-break has occurred at a relatively "normal" time in many growing regions, at least compared to the last few drought years, and vineyard managers are anticipating the likely effects on the grapes going into the 2017 vintage.
Vineyard blocks featuring efficient drainage are expected to undergo a rapid but relatively straightforward start, with general tendency toward abundant water availability in the root zone, improved soil structure, and lowered salinity levels thanks to the flushing of drought-affected soils. To maintain vine balance and promote timely cluster ripening, a close eye will have to be trained on the canopy, which is likely to display heightened vigor.
For vineyard blocks that experienced extended periods of standing water this winter, there are added considerations. Whether the pooling was caused by large amounts of runoff from higher blocks nearby or clay soils contributing to poor drainage, vines in these areas may show marked variations in vigor as the growing season gets underway.
In poorly drained soils, though the vineyard floor appears dry, supersaturated conditions may still exist in the root zone. In this case, vines can exhibit signs of "spring sickness" or "wet feet" caused by hypoxic conditions in the soil environment. When these conditions are short-lived, the effect on the vine is rarely fatal, but partial root death may slow early-season growth.
Some of these areas may actually see an increase in salinity, as the water that was pooled there likely contained high concentrations of salts leached from other, better-drained areas.
Increased salinity can also come from below, particularly where perched groundwater is present. Rising water tables can dissolve salts built up through irrigation in dry years and deposit them higher up in the soil profile as water levels recede, possibly in the root zone.
Under both hypoxic and saline soil conditions, the vines' ability to regulate sodium and chloride ion concentrations in their roots is decreased; interfering with the normal uptake of essential nutrients such as nitrogen, phosphorus, and calcium.
Thus, some vineyard blocks that were partially affected by flooding in the past months may exhibit higher variation in vigor than has been seen in recent years, potentially bringing added complication to the all-important task of canopy management.
Hawk Aerial provides highly accurate vigor mapping by collecting data on the proportion of specific wavelengths of light reflected by vine foliage - which differs significantly with the intensity of photosynthesis occurring in the plant at the time of image capture. We then use this information to create maps displaying explicit visual differences between areas of high vigor and areas of low vigor - a very rapid way to gather crucial information informing canopy management strategy.
In contrast to the vast majority of NDVI-derived maps on the market today, our data products undergo processing that removes interference generated by ambient light quality and reflectance from cover crop and other non-vine vegetation - showing you the vigor levels of your vines, period. Vigor mapping not only gives your vineyard management professionals a roadmap from which to start in their short-term planning, but also creates a record over time that can shed light on areas of the vineyard featuring chronically high or low vigor. This can drive decisions on more involved intervention, such as soil amendment, installation of drainage infrastructure, et cetera.
Our Calibrated Enhanced Vegetation Index (CEVI) package provides growers and vineyard managers with three ultra-high-resolution, scale-accurate, georeferenced maps per imaging mission, details of which can be found by clicking the buttons below. Contact us to book an imaging mission today, and get a head start on your canopy management planning!