August 3, 2015

This report covers conditions and observations made between Monday, June 29 and Sunday, August 2, 2015. The next report is scheduled for Monday, August 31, 2015. However, in the event of any significant occurrences prior to that date, this site will be updated as soon as possible.

Taken along the west side of Stanislaus County, this report’s photos present the hull split of the Nonpareil, a shaker bringing the Nonpareil to the ground and the hull split of the traditionally last to harvest Fritz.

Temperatures varied widely during July, with significant heat waves impacting the orchards during the first days of the month and again during the transition into August. Daily maximum temperatures reached above the century mark during these hotter periods, increasing stress levels and the moisture demand by the crop. In between these uncomfortable periods, highest readings were reported at more comfortable, but warm levels, with readings ranging between the lower 80s and mid 90s. Morning minimum readings during the period also remained at relatively warm levels, ranging between the upper 50s and lower 70s.

Aside from the hot conditions, the most significant factor in the period’s weather was contributed by monsoonal moisture flowing northward from tropical storms over Mexico. Elevated humidity levels made for uncomfortable conditions while thunderstorms produced sporadic showers that dropped trace amounts of rain in isolated areas of the region.

Harvest operations have begun in the Northern San Joaquin Valley. Shakers were sent into the first of the region’s orchards along the I-5 corridor during mid-July, with shaking operations starting along the eastern foothills during the final week of the period. Only a few orchards have been picked up as this report was being prepared and observers are reporting that harvest operations in all areas of the region will be going strong during the first ten days of August.

Growers spent the month of July preparing for the harvest and working to meet their orchards moisture needs. Special consideration has been given to hull split treatments for Navel Orange Worm, NOW, this year. As has been noted in previous reports, growers and Pest Control Advisors have reported very high trap counts of this serious insect pest throughout the growing season. The combination of poor mummy shaking conditions due to the dry winter and elevated temperatures during the growing season have resulted in a significant population of moths within the region’s orchards. Growers have made two and in some case three treatments to control the pest and hopefully prevent damage to the crop. Growers have also noted problems with hull rot, produced by the elevated humidity levels and have opted to include treatments for the fungal organisms causing the problems with the treatments for NOW. While fungal growth on the hulls is not a serious problem by itself, the organism produces toxins that attack wood and can significantly impact crop production in subsequent years.

Water remains a focal point for all in the region. Heavy rain falling from thunderstorms within the Sierra Nevada watershed produced enough water to allow the Merced Irrigation District to release 0.4 acre/inch of water to its growers. While this may seem insignificant, it did provide some growers with an opportunity accumulate water from the various lands they own, and provide their orchards with an irrigation without using groundwater. Water will be available to growers within the Modesto and Turlock Irrigation Districts until early October. Growers there have effectively rationed their supplies of surface water, balancing availability with water drawn from their wells to meet the needs of their orchards. However, deficit irrigation remains the norm and orchards under significant stress can be observed in all areas of the region. Damage from water stress and excessive salinity and/or pH has impacted tree growth, thereby impacting the current crop and potentially, crops to follow.


Current weather at the National Weather Service
Mel Machado
Jereme Fromm

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