June 1, 2015

This report covers conditions and observations made between Monday, May 4 and Sunday, May 31, 2015. The next report is scheduled for Monday, June 29, 2015. However, in the event of any significant occurrences prior to that date, this site will be updated as soon as possible.

The first of this report’s photos for the northern region present a shot of the Carmel and an orchard under irrigation after it has received a fertilizer application, both in the Chico area of Butte County. Our final image shows a pumping plant in the Tehama-Colusa Canal moving water towards the orchards along the west side of the region.

Mild conditions dominated the Sacramento Valley’s weather during the period, reducing the orchard’s moisture requirements, allowing the crop to develop relatively stress free. Daily maximum temperatures dropped from the upper 70’s in the period’s opening days to the upper 60’s and lower 70’s by mid-month, as clouds rolled over the region from storm systems spinning over Nevada. Readings then gradually increased, reaching their greatest values in the period’s closing days in the upper 80’s and lower 90’s. Meanwhile, morning lows were widely reported in the upper 40’s to lower 50’s throughout the period. While the weather systems lying east of the region promoted the reduced temperatures, the more northerly location of the Sacramento Valley prevented the more widespread rain received in the San Joaquin Valley from reaching the region’s orchards, with only a few hundredths of an inch reported.

Observers are reporting that the crop developed nicely during May, benefitting from the mild conditions. Kernels of all varieties are now completely solidified, or nearly so and have reached their maximum weight. Coincident with the mild temperatures, growers were able to scale back irrigations during the period, thus saving water while not impacting the developing nuts. As shown in the accompanying photo, some growers along the west side of the region have been pumping water into the Tehama-Colusa Canal, moving it to other properties they own; in some cases, lifting the water uphill.

Orchards in the region are in generally good condition with little evidence of disease at this time. Growers have been treating to prevent Scab and Rust infections, applications that must be made prior to infection in order to be effective. Some have also begun treatments with preventative miticides, targeted at the most damaging species of spider mites that can promote premature defoliation of the trees.

Growers are also monitoring populations of Navel Orange Worm (NOW) using pheromone traps to attract male moths and egg traps to monitor egg laying by females. Many in the region are speculating on the potential for an early hull split this year, given the apparently advanced stage of development. Some have noted that they were also expecting an earlier than normal timing in the 2014 crop and skipped treatments for NOW in the hopes that an early harvest would reduce losses. For many, that strategy failed, resulting in excessive damage levels in the 2014 crop. Growers and their Pest Control Advisors will be watching crop and insect cycles closely in the coming weeks in an effort to avoid the damage suffered in 2014.

Current weather at the National Weather Service
Ryan Christy
Dennis Meinberg

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