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 southern region present an example of an orchard under irrigation near in the Chowchilla area of Madera County, followed by shots of the developing crops on the Independence and Nonpareil varieties in Tulare County. Finally, our feature image shows a flail mower working its way through an orchard near Chowchilla.

Warm, dry conditions dominated the weather in the southern San Joaquin during the second half of March, setting a few new high temperature records in the period’s final week. Comfortable temperatures dominated early in the period, with daily maximum readings reported between the upper 60’s to upper 70’s . However, temperatures turned decidedly warmer in the period’s closing days, with readings rising into the upper 80’s and lower 90’s in several locations. Morning low readings were much more stable, ranging predominately between the mid 40’s and lower 50’s throughout the period.

While the weather has provided excellent conditions for the developing crop, pushing growth rates aggressively, the unseasonably warm temperatures have exacerbated grower’s concerns about water. Surface water from local irrigation districts is largely unavailable this year, compelling growers in the southern San Joaquin to rely on wells. However, growers are already encountering problems with their wells that were not noted until mid to late summer last year. Flow rates coming from wells have declined and growers have reported that several wells have collapsed. At this point, the crop is developing rapidly and is in generally good condition. However, adverse impacts from moisture stress will become more dominant in the coming weeks if growers are not able to meet the trees moisture requirements. While the water required to grow almonds has received quite a bit of coverage in the popular media over the past year, it must be noted that nearly all crops grown in the Central Valley require the same quantity of water, 3 to 4 acre/feet per acre. In fact, the wide-spread adoption of low-volume drip and micro-sprinkler irrigation practices, which were pioneered by almond growers has increased yields by optimally providing water to the trees while minimizing losses.

Observers have reported that the signs of water issues, both quantity and quality can be easily seen within the region’s orchards. There is quite a bit of variability in crop loads visible within the region’s orchards, with plantings that experienced the greatest degree of stress last year exhibiting correspondingly weaker crop loads this year. Orchards displaying a decidedly yellow cast can also be easily spotted in the southern San Joaquin; the result of groundwater with too high a pH value.

Growers have set pheromone traps in their orchards to monitor populations of Peach Twig Borer and Navel Orange Worm, NOW. Pest Control Advisors have reported catching significant numbers of NOW male moths in these traps and they are also keeping an eye on egg traps designed to monitor egg laying by female moths within the orchards. Growers are also watching closely for the first signs of Leaf-Footed Plant Bugs. No economic thresholds have yet been established for this insect, which can wreak havoc in orchards by feeding on the developing nuts with its piercing-sucking mouthparts, much like a mosquito. With no threshold established, growers and their Pest Control Advisors must watch the fields closely for signs of feeding as the insect can move very quickly through an orchard causing significant crop losses. Observers have reported that some growers in the Sanger area of Fresno County have been forced to treat as the insect moved in from the drying grasslands to the east.

In addition to scrambling for water, growers have been reducing vegetation within the orchards, controlling rodents and fertilizing the trees. Those planting new orchards have been working to complete the required work to get their trees in the ground and install irrigation systems. Observers have noted that beekeepers have yet to remove the last of the hives from the region’s orchards. These colonies must be removed before any insect management treatments can begin.

Current weather at the National Weather Service
Ernie Reichmuth and Mat Willson
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