March 30, 2015

This report covers conditions and observations made between Monday March 16 and Sunday, March 29, 2015. The next report is scheduled for Monday, May 4, 2015. However, in the event of any significant occurrences prior to that date, this site will be updated as soon as possible.

This report’s photos for the central region present the developing crop along the west side of Merced and Stanislaus Counties. Our first image provides a glimpse down the row of the Nonpareil and Monterey, near the now drying coast range mountains. Simply turning 180 degrees within the same orchard and looking across the road, our second photo provides an example of the diversity in orchard health visible, showing the noticeably yellow foliage of a Butte and Padre planting suffering the effects of high pH water. Our final image shows an orchard roller smoothing the orchard floor in a Butte and Padre planting south of Tracy where the grower has opted to till the orchard floor, while our feature photo shows the developing nuts of the Nonpareil, near Gustine.

Warm conditions reigned over the central region during the latter half of March, setting a few records and generally providing excellent conditions for the developing crop. Daily maximum readings were reported predominately in the lower 70’s to upper 80’s during the period, with readings dipping  briefly into the upper 60’s on the 23rd and 24th of the month, when a very weak system dropped trace amounts of rain in northern areas of the region during the overnight hours. Morning minimum readings exhibited a bit more stability, ranging from the lower 40’s to lower 50’s each day.

Crop development continues at a brisk pace in the northern San Joaquin Valley, under the influence of the warm conditions. Throughout the region, the differentiation process has been completed in all varieties and the smallest of the nuts have been shed from the trees. The warm temperatures have aided this process, by allowing a greater proportion of the smaller sized nuts to be retained. Advanced orchards around the region are now entering the second phase of shedding, a process that normally occurs during mid-April, thus signaling the advance nature of the crop.

While the South San Joaquin and Oakdale Irrigation Districts have begun their delivery season, allowing growers there to begin irrigating, growers in the Turlock and Modesto Irrigation District are still waiting for their canals to be filled. Growers in the Turlock and Modesto Districts are anticipating receiving approximately 16 inches of water this year, with deliveries beginning within the next two weeks. Some growers who have no water of their own available have opted to purchase water drawn from district-owned deep wells in order to meet their orchard’s early season needs. While the elevated temperatures have provided strong support for the developing crop, they have also increased water consumption, increasing stresses in orchards that have not yet been irrigated. Breezy conditions on several days during the period exacerbated the situation, as wind speeds in the teens increased water movement through the trees. Growers in the Merced Irrigation District face particularly grim prospects this year, with no deliveries of surface water available. Growers there are relying solely on deep wells this year, with growers who have no wells of their own forced to purchase water from wells owned by the District or their neighbors. Growers within the boundaries of the federal Central Valley Project will also receive no surface water this year and face a similar fate.

As may be seen in the second photo accompanying this report, a wide range of variation in orchard health can be easily seen within the region’s plantings. Orchards irrigated with high pH water from deep wells have begun taking on a noticeably yellow hue. This is most easily observed along the west side of the valley. However, as shown in the photo, the symptoms can be highly localized with adjacent orchards receiving water from different wells showing no sign of problems.

To provide support for the crop, growers have been fertilizing their orchards, mowing weed growth and controlling gophers within the orchards. Traps to monitor populations of Peach Twig Borer and Navel Orange Worm have also been set in the orchards, which will help to properly time treatments that may be required later in the season. Growers are also on high alert for signs of Leaf-Footed Plant Bugs. University of California Farm Advisors have sounded the alarm for this serious pest, noting that the insect tends to move from grassland areas as they dry. Growers will focus their attention on the Sonora, Aldrich, Price and Fritz varieties, which this insect prefers.

While the risk of frost has not completely vanished, the elevated daytime temperatures eliminated the risk of damage during the month and growers are hopeful that morning temperatures will remain at comfortable levels in the next few weeks. Over the next month, irrigation will be the prime activity as growers balance limited supplies of water against the increasing moisture needs of their orchards.

Current weather at the National Weather Service
Mel Machado
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